Patent Publication Number: US-2022218325-A1

Title: Tissue retractor, retraction modules, and associated methods

Description:
CROSS-REFERENCE TO RELATED U.S. PATENT APPLICATION 
     This application is a continuation in part of: U.S. Nonprovisional patent application Ser. No. 17/683,925 entitled “Tissue Retractor, Retraction Modules, and Associated Methods,” filed Mar. 1, 2022 which is a continuation in part of U.S. Nonprovisional patent application Ser. No. 17/336,860 entitled “Tissue Retractor, Retraction Modules, and Associated Methods,” filed Jun. 2, 2021 which is a continuation in part of U.S. Nonprovisional patent application Ser. No. 16/926,173 entitled “Tissue Retractor,” filed Jul. 10, 2020. This application also claims priority to U.S. Provisional Application Ser. No. 63/254,929 filed Oct. 12, 2021. The entire disclosure of each of the above applications is incorporated by reference in its entirety. 
    
    
     FIELD 
     The present technology is generally related to medical devices to assist a surgeon during treatment of musculoskeletal disorders, and more particularly to a surgical system and method for accessing a surgical site to facilitate treatment. More particularly, the present disclosure is directed to a surgical retractor system including a primary retractor assembly and a secondary retractor assembly that are configured for various approaches to the spine, including for example, anterior, lateral, and oblique surgical techniques. 
     BACKGROUND 
     Spinal disorders such as degenerative disc disease, disc herniation, osteoporosis, spondylolisthesis, stenosis, scoliosis and other curvature abnormalities, kyphosis, tumor, and fracture may result from factors including trauma, disease and degenerative conditions caused by injury and aging. Spinal disorders typically result in symptoms including pain, nerve damage, and partial or complete loss of mobility. 
     Non-surgical treatments, such as medication, rehabilitation and exercise can be effective, how-ever, may fail to relieve the symptoms associated with these disorders. Surgical treatment of these spinal disorders includes fusion, fixation, discectomy, laminectomy and implantable prosthetics. Surgical retractors may be employed during a surgical treatment to provide access and visualization of a surgical site. Such retractors space apart and support tissue and/or other anatomical structures to expose anatomical structures at the surgical site and/or provide a surgical pathway for the surgeon to the surgical site. 
     SUMMARY 
     This disclosure describes a plurality of different embodiments and modules for use as a modular retractor system. The system may use any of the variously disclosed blades, extendable blades, and dilators. Additionally, this disclosure describes a quick connect and release coupler for securing the modular retractor system to a table mount. 
     In an aspect, this disclosure describes a retractor system for enabling access to a surgical site. The system may include a modular retractor having a longitudinal axis extending in a longitudinal direction and a lateral axis extending from a first lateral end to a second lateral end in a lateral direction, for example. In various embodiments, the modular retractor may include a first body portion that houses a distraction mechanism, a first arm and a second arm pivotally coupled together, and a first handle coupled to the first arm and a second handle coupled to the second arm. In various embodiments, the modular retractor may further include a first pivoting member coupled to a distal end of the first arm and a second pivoting member coupled to a distal end of the second arm, a first attachment mechanism coupled to the first pivoting member and supporting a first pin receiving cannula, and a second attachment mechanism coupled to the second pivoting member and supporting a second pin receiving cannula. In various embodiments, the modular retractor may include a first actuator operably coupled to the distraction mechanism for opening and closing the first arm and the second arm, a second actuator for adjusting the angulation of the first pivoting member, and a third actuator for adjusting the angulation of the second pivoting member, for example. In at least some embodiments, the first body portion comprises at least one table mount quick release coupler. 
     In another aspect, this disclosure provides for a retractor system for enabling access to a surgical site. The retractor may have a longitudinal axis extending in a longitudinal direction and a lateral axis extending from a first lateral end to a second lateral end in a lateral direction. In various embodiments, the retractor may include a first arm and a second arm pivotally coupled together, a third arm extendable forward and backward in the longitudinal direction, and a first handle coupled to the first arm and a second handle coupled to the second arm, for example. In various embodiments, the retractor may include a first pivoting member coupled to a distal end of the first arm, and a second pivoting member coupled to a distal end of the second arm, a first attachment mechanism coupled to the first pivoting member and supporting a first pin receiving cannula, and a second attachment mechanism coupled to the second pivoting member and supporting a second pin receiving cannula, for example. In various embodiments, the retractor may include a first actuator for opening the first arm and the second arm, a second actuator for adjusting the angulation of the first pivoting member, a third actuator for adjusting the angulation of the second pivoting member, and a fourth actuator comprising a toothed gear for moving the third arm forward and backward in the longitudinal direction, for example. In various embodiments, the toothed gear may be meshed with a rack portion of the third arm, and the first body portion may include at least one table mount quick release coupler, for example. 
     In another aspect, this disclosure provides for a tissue retraction method. The method including the step of providing a retractor system for enabling access to a surgical site. The retractor may have a longitudinal axis extending in a longitudinal direction and a lateral axis extending from a first lateral end to a second lateral end in a lateral direction. In various embodiments, the retractor may include a first arm and a second arm pivotally coupled together, a third arm extendable forward and backward in the longitudinal direction, and a first handle coupled to the first arm and a second handle coupled to the second arm, for example. In various embodiments, the retractor may include a first pivoting member coupled to a distal end of the first arm, and a second pivoting member coupled to a distal end of the second arm, a first attachment mechanism coupled to the first pivoting member and supporting a first pin receiving cannula, and a second attachment mechanism coupled to the second pivoting member and supporting a second pin receiving cannula, for example. In various embodiments, the retractor may include a first actuator for opening the first arm and the second arm, a second actuator for adjusting the angulation of the first pivoting member, a third actuator for adjusting the angulation of the second pivoting member, and a fourth actuator comprising a toothed gear for moving the third arm forward and backward in the longitudinal direction, for example. In various embodiments, the toothed gear may be meshed with a rack portion of the third arm, and the first body portion may include at least one table mount quick release coupler, for example. The method may include the steps of attaching a first pin receiving cannula to the first attachment mechanism and attaching a second pin receiving cannula to the second attachment mechanism, for example. The method may further include the steps of attaching a first cervical blade to a first free hand module supported by a distal mount and attaching a second cervical blade to a second free hand module supported by a proximal mount, for example. The method may further include the steps of driving a first pin through an aperture of the first pin receiving cannula and driving a second pin through an aperture of the second pin receiving cannula, for example. The method may further include the steps of connecting the first pin to a first vertebrae and connecting the second pin to a second vertebrae, for example. 
     The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of an exemplary embodiment of a retractor system including a primary retractor assembly and a secondary retractor assembly in accordance with the principles of the disclosure. 
         FIG. 2  is a perspective view of the primary retractor assembly of  FIG. 1  in accordance with the principles of the disclosure. 
         FIG. 3  is a perspective view of the secondary retractor assembly of  FIG. 1  in accordance with the principles of the disclosure. 
         FIG. 4  is a perspective view of the retractor system of  FIG. 1  including a plurality of blades in accordance with the principles of the disclosure. 
         FIG. 5  is a top down view of the primary retractor assembly of  FIG. 2  in accordance with the principles of the disclosure. 
         FIG. 6  is a top down view of the secondary retractor assembly of  FIG. 3  in accordance with the principles of the disclosure. 
         FIG. 7  is a cutaway view of the retractor system of  FIG. 1  in accordance with the principles of the disclosure. 
         FIG. 8  is an alternate cutaway view of the retractor system of  FIG. 1  in accordance with the principles of the disclosure. 
         FIG. 9  is a perspective view of an exemplary blade for use with the retractor system of  FIG. 1  in accordance with the principles of the disclosure. 
         FIG. 10  is an alternate perspective view of an exemplary blade and pin for use with the retractor system of  FIG. 1  in accordance with the principles of the disclosure. 
         FIG. 11  is a perspective view of an exemplary blade and shim for use with the retractor system of  FIG. 1  in accordance with the principles of the disclosure. 
         FIG. 12  is a perspective view of an exemplary set of nested dilators for coordinated use with the retractor system of  FIG. 1  in accordance with the principles of the disclosure. 
         FIG. 13A  is a top down view of the set of nested dilators of  FIG. 12 , and  FIG. 13B  is a top down view of a plurality of blades for use with the retractor system of  FIG. 1  in accordance with the principles of the disclosure. 
         FIG. 14  is a top down view of an exemplary retractor system having a plurality of blades surrounding a set of nested dilators in accordance with the principles of the disclosure. 
         FIG. 15  is a top down view of an exemplary retractor system of  FIG. 14  in a first partially expanded position after removal of the set of nested dilators in accordance with the principles of the disclosure. 
         FIG. 16  is a top down view of an exemplary retractor system of  FIG. 14  in the first partially expanded position in accordance with the principles of the disclosure. 
         FIG. 17  is a side view of the exemplary retractor system of  FIG. 14  having a plurality of blades surrounding a set of nested dilators in accordance with the principles of the disclosure. 
         FIG. 18  is a side view of the exemplary retractor system of  FIG. 14  in a second expanded position in accordance with the principles of the disclosure. 
         FIG. 19  is a side view of the exemplary retractor system of  FIG. 14  in the second expanded position in accordance with the principles of the disclosure. 
         FIG. 20  is a perspective view of a modular retractor. 
         FIG. 21  is a perspective view of a modular retractor. 
         FIG. 22  is a top down view of a modular retractor. 
         FIG. 23  is a perspective view of an adjustment tool for use with disclosed modular retractor embodiments. 
         FIG. 24  is a top down exploded parts view of a modular retractor. 
         FIG. 25  is a perspective exploded parts view of a modular retractor. 
         FIG. 26A  is a perspective view of a distraction mechanism for use with disclosed modular retractor embodiments. 
         FIG. 26B  is a top perspective view of a distraction mechanism. 
         FIG. 26C  is an enlarged top perspective view of a distraction mechanism. 
         FIG. 26D  is a bottom perspective view of a distraction mechanism. 
         FIG. 26E  is an enlarged bottom perspective view of a distraction mechanism. 
         FIG. 27A  is a top down view of a modular retractor coupled to a table mount. 
         FIG. 27B  is a perspective view of a modular retractor coupled to a table mount. 
         FIG. 28A  is a perspective view of a table mount rack. 
         FIG. 28B  is a perspective view of a table mount rack. 
         FIG. 28C  is an exploded parts view of a table mount rack. 
         FIG. 29  is a top perspective view of a first module for use with disclosed modular retractor embodiments. 
         FIG. 30  is a top perspective view of a first module for use with disclosed modular retractor embodiments. 
         FIG. 31A  is a bottom perspective view of a first module for use with disclosed modular retractor embodiments. 
         FIG. 31B  is a bottom perspective view of a first module for use with disclosed modular retractor embodiments. 
         FIG. 32  is an exploded parts view of a first module for use with disclosed modular retractor embodiments. 
         FIG. 33A  is a perspective view of a first module coupled to a modular retractor. 
         FIG. 33B  is a perspective view of a first module coupled to a modular retractor. 
         FIG. 34  is a top down view of a first module coupled to a modular retractor and a plurality of blades. 
         FIG. 35  is a top perspective view of a second module for use with disclosed modular retractor embodiments. 
         FIG. 36  is a top perspective view of a second module for use with disclosed modular retractor embodiments. 
         FIG. 37  is a bottom perspective view of a second module for use with disclosed modular retractor embodiments. 
         FIG. 38  is a bottom perspective view of a second module for use with disclosed modular retractor embodiments. 
         FIG. 39  is an exploded parts view of a second module for use with disclosed modular retractor embodiments. 
         FIG. 40  is a top down view of a second module coupled to a modular retractor and a plurality of blades. 
         FIG. 41A  is a top perspective view of a third module for use with disclosed modular retractor embodiments. 
         FIG. 41B  is a bottom perspective view of a third module for use with disclosed modular retractor embodiments. 
         FIG. 42  is an exploded parts view of a third module for use with disclosed modular retractor embodiments. 
         FIG. 43  is a perspective view of a third module coupled to a modular retractor. 
         FIG. 44  is a perspective view of a third module coupled to a modular retractor and a plurality of blades. 
         FIG. 45A  is a top perspective view of an alternate embodiment of a third module. 
         FIG. 45B  is a bottom perspective view of an alternate embodiment of a third module. 
         FIG. 46  is a perspective view of a free hand module coupled to a third module for use with disclosed modular retractor embodiments. 
         FIG. 47A  is a side view of a free hand module for use with disclosed modular retractor embodiments. 
         FIG. 47B  is a side view of a free hand module for use with disclosed modular retractor embodiments. 
         FIG. 48A  is an exploded parts view of a free hand module. 
         FIG. 48B  is a perspective view with partially removed parts of a free hand module. 
         FIG. 49A  is a perspective view of a free hand module in a sliding configuration. 
         FIG. 49B  is a perspective view of a free hand module in a second position. 
         FIG. 50  is a perspective view of a free hand module and an telescoping blade system. 
         FIG. 51  is a perspective view of an telescoping blade system. 
         FIG. 52A  is a perspective view of a blade connection channel. 
         FIG. 52B  is a perspective view of a blade fastener. 
         FIG. 53  is a perspective view of a third module coupled to a modular retractor and a free hand module coupled to the third module. 
         FIG. 54  is a perspective view of a third module coupled to a modular retractor and a free hand module coupled to the third module. 
         FIG. 55  is a top perspective view of a fourth module for use with disclosed modular retractor embodiments. 
         FIG. 56  is a bottom perspective view of a fourth module for use with disclosed modular retractor embodiments. 
         FIG. 57  is an exploded parts view of a fourth module. 
         FIG. 58  is a top down view of a fourth module coupled to a modular retractor. 
         FIG. 59  is a perspective view of a fourth module coupled to a modular retractor. 
         FIG. 60  is a perspective view of a fourth module coupled to a modular retractor and first and second free hand modules coupled to the fourth module. 
         FIG. 61  is a perspective view of a fourth module coupled to a modular retractor and first and second free hand modules coupled to the fourth module. 
         FIG. 62  is a top perspective view of a fifth module for use with disclosed modular retractor embodiments. 
         FIG. 63  is a bottom perspective view of a fifth module for use with disclosed modular retractor embodiments. 
         FIG. 64  is an exploded parts view of a fifth module. 
         FIG. 65  is a top perspective view of a fifth module. 
         FIG. 66  is a top view of a pair of blades for use with disclosed modular retractor embodiments. 
         FIG. 67  is a bottom view of a pair of blades for use with disclosed modular retractor embodiments. 
         FIG. 68  is a perspective view of a pair of blades for use with disclosed modular retractor embodiments. 
         FIG. 69  is an enlarged view of a top portion of a universal blade fastener. 
         FIG. 70  is a top view of three blades for use with disclosed modular retractor embodiments. 
         FIG. 71  is a bottom view of three blades for use with disclosed modular retractor embodiments. 
         FIG. 72  is a perspective view of three blades for use with disclosed modular retractor embodiments. 
         FIG. 73  is a top view of four blades for use with disclosed modular retractor embodiments. 
         FIG. 74  is a bottom view of four blades for use with disclosed modular retractor embodiments. 
         FIG. 75  is a perspective view of four blades for use with disclosed modular retractor embodiments. 
         FIG. 76  is a top view of a plurality of nested dilators. 
         FIG. 77A  is a perspective view of a plurality of nesting dilators of  FIG. 76  in a non-nested configuration. 
         FIG. 77B  is a perspective view of a plurality of nesting dilators in a nested configuration. 
         FIG. 78  is a top view of a dilator. 
         FIG. 79  is a perspective view of the dilator of  FIG. 78 . 
         FIG. 80A  is a top view of a dilator. 
         FIG. 80B  is a perspective view of the dilator of  FIG. 80A . 
         FIG. 80C  is a perspective view of a set of nested and cylindrically shaped dilators. 
         FIG. 80D  is an elevation view of the various dilators of embodiment of  FIG. 80C . 
         FIG. 80E  is a perspective view of the various dilators of embodiment of  FIG. 80C . 
         FIG. 81  is a top down view of the various dilators of embodiment of  FIG. 80C . 
         FIG. 82  is a perspective view of a modular blade. 
         FIG. 83  is a perspective view of a modular blade. 
         FIG. 84  is a perspective view of an extendable blade for coupling to the modular blade of  FIGS. 82-83 . 
         FIG. 85  is a perspective view of an extendable blade for coupling to the modular blade of  FIGS. 82-83 . 
         FIG. 86  is a front view of the modular blade of  FIGS. 82-83  and the extendable blade of  FIGS. 84-85 . 
         FIG. 87  is a top down view of the modular blade of  FIGS. 82-83  and the extendable blade of  FIGS. 84-85 . 
         FIG. 88  is a perspective view of a modular blade. 
         FIG. 89  is a perspective view of a modular blade. 
         FIG. 90  is a perspective view of an extendable blade for coupling to the modular blade of  FIGS. 82-83 . 
         FIG. 91  is a perspective view of an extendable blade for coupling to the modular blade of  FIGS. 88-89 . 
         FIG. 92  is a front view of the modular blade of  FIGS. 88-89  and the extendable blade of  FIGS. 90-91 . 
         FIG. 93  is a top down view of the modular blade of  FIGS. 88-89  and the extendable blade of  FIGS. 90-91 . 
         FIG. 94  is a perspective view of a modular blade. 
         FIG. 95  is a perspective view of a modular blade. 
         FIG. 96  is a perspective view of an extendable blade for coupling to the modular blade of  FIGS. 94-95 . 
         FIG. 97  is a perspective view of an extendable blade for coupling to the modular blade of  FIGS. 94-95 . 
         FIG. 98  is a front view of the modular blade of  FIGS. 94-95  and the extendable blade of  FIGS. 96-97 . 
         FIG. 99  is a top down view of the modular blade of  FIGS. 94-95  and the extendable blade of  FIGS. 96-97 . 
         FIG. 100  is a perspective view of a modular blade. 
         FIG. 101  is a perspective view of a modular blade. 
         FIG. 102  is a perspective view of an extendable blade for coupling to the modular blade of  FIGS. 100-101 . 
         FIG. 103  is a perspective view of an extendable blade for coupling to the modular blade of  FIGS. 100-101 . 
         FIG. 104  is a perspective view of an extendable blade for coupling to the modular blade of  FIGS. 100-101 . 
         FIG. 105  is a front view of the extendable blades of  FIGS. 103-105 . 
         FIG. 106  is a perspective view of the outside surfaces of a modular blade and an extendable blade having a pointed end. 
         FIG. 107  is a perspective view of the inside surfaces of the modular blade and the extendable blade of  FIG. 106 . 
         FIG. 108A  is a first exploded parts view of the modular blade and extendable blade of  FIGS. 106-107 . 
         FIG. 108B  is a second exploded parts view of the modular blade and extendable blade of  FIGS. 106-107 . 
         FIG. 108C  is a perspective view of the modular blade of  FIGS. 106-107 . 
         FIG. 108D  is a top down view of the modular blade of  FIGS. 106-107 . 
         FIG. 108E  is a perspective view of an impact driver for use with the modular blade and extendable blade of  FIGS. 106-107 . 
         FIG. 109  is a perspective view of a square shaped dilator. 
         FIG. 110  is a bottom perspective view of a pair of shims for coupling to various blades disclosed herein. 
         FIG. 111  is a perspective view of a relatively short shim having a pointed pin at a distal end thereof. 
         FIG. 112  is a perspective view of a relatively tall shim having a pointed pin at a distal end thereof. 
         FIG. 113  is a perspective view of a relatively tall shim having a blunted distal end. 
         FIG. 114  is a perspective view of a double-sided shim for coupling to various blades disclosed herein. 
         FIG. 115A  is a perspective view of a blade adjustment and positioning tool. 
         FIG. 115B  is an exploded parts view of a blade adjustment and positioning tool. 
         FIG. 116A  is a perspective view of the blade adjustment and positioning tool engaged with a modular blade and an extendable blade. 
         FIG. 116B  is a perspective view of the blade adjustment and positioning tool engaged with a modular blade and an extendable blade. 
         FIG. 117A  is a perspective view of the inside surfaces of a modular blade and an extendable blade having a footed tip at the distal end thereof. 
         FIG. 117B  is a perspective view of the modular blade and extendable blade of  FIG. 117A . 
         FIG. 118A  is a perspective view of a quick connect handle. 
         FIG. 118B  is an exploded parts view of a quick connect handle. 
         FIG. 118C  is a perspective view of a retractor mount coupler. 
         FIG. 118D  is a perspective view of the modular and extendable blades of  FIGS. 117A-117B  coupled to the quick connect handle of  FIGS. 118A-118B  and the retractor mount coupler of  FIG. 118C . 
         FIG. 118E  is a perspective view of the modular and extendable blades of  FIGS. 117A-117B  before being coupled to the quick connect handle of  FIGS. 118A-118B . 
         FIG. 119  is a first perspective view of an additional embodiment of a modular retractor. 
         FIG. 120  is a second perspective view of the additional embodiment of the modular retractor of  FIG. 119 . 
         FIG. 121A  is a top down view of the embodiment of  FIGS. 119-120 . 
         FIG. 121B  is a bottom perspective view of a blade coupling portion. 
         FIG. 122A  is an enlarged view of the embodiment of  FIGS. 119-121  from a top perspective with the top cover removed for ease of understanding of the internal gear system. 
         FIG. 122B  is an enlarged view of the embodiment of  FIGS. 119-121  from a bottom perspective showing various structural features of a table mount quick connect coupler. 
         FIG. 123  is a perspective view of various armatures of a quick connect table mount system for supporting various retractor embodiments disclosed herein. 
         FIG. 124  is a first perspective view of a quick connect coupler for connecting various retractor embodiments to various quick connect table mount systems disclosed herein. 
         FIG. 125  is a side view of the quick connect coupler of  FIG. 124 . 
         FIG. 126  is a perspective view of a modular retractor system including the quick connect couplers of  FIGS. 124-125 . 
         FIG. 127  is a top down view of the system of  FIG. 126 . 
         FIG. 128  is a perspective view of a secondary module that may be coupled and uncoupled with various primary retractor embodiments. 
         FIG. 129  is a perspective view of the secondary module of  FIG. 128  coupled to a primary retractor. 
         FIG. 130  is a top down view of a modular retractor supporting first and second blades to be slidably coupled to an outermost dilator. 
         FIG. 131  is a perspective view of the three blades being slidably coupled to an outermost dilator. 
         FIG. 132  is a perspective view of a modular retractor system during use. 
         FIG. 133  is a second perspective view of a modular retractor system. 
         FIG. 134  is a top down view of a modular retractor system. 
         FIG. 135  is an enlarged top down view of a region of  FIG. 134 . 
         FIG. 136  is a top down view of a modular retractor system. 
         FIG. 137  is a perspective view of a pair of blades for use with various modular retractor systems disclosed herein. 
         FIG. 138  is a perspective view of a pin delivery cannula for use with various modular retractor systems disclosed herein. 
         FIG. 139  is a perspective view of a pin for use with the pin delivery cannula of  FIG. 138 . 
         FIG. 140  is a perspective view of the pin delivery cannula of  FIG. 138  and the pin of  FIG. 139  in an example operative configuration. 
         FIG. 141  is a perspective view of a support module for attaching to arm portions of various modular retractor systems disclosed herein. 
         FIG. 142  is an example flow chart method of use of disclosed modular retractor systems. 
         FIG. 143  is a reference drawing showing the human spine of which various disclosed implant embodiments may be installed in. 
         FIG. 144  is a reference drawing showing various planes and reference directions of which the various disclosed implant embodiments may move in or act in with respect to a patient. 
     
    
    
     DETAILED DESCRIPTION 
     In one aspect, exemplary embodiments describe a retractor system  100  for use with anterior, lateral, and oblique surgical techniques. At least one use of retractor system  100  is to assist in the preparation of a surgical site to enable a surgeon to access a space between vertebrae of patient&#39;s spine. The retractor system  100  may assist a surgeon in accessing a space between vertebrae by enabling highly controlled dilation of the paraspinous muscles with a set of nested dilators and retraction of the various fibers and tissues at the surgical site with the use of a plurality of independently movable and inclinable blades. 
     Referring generally to  FIGS. 1-8  exemplary retractor systems for enabling access to a surgical site are disclosed.  FIG. 1  is a perspective view of an exemplary embodiment of a retractor system  100  including a primary retractor assembly  200  and a secondary retractor assembly  300  in accordance with the principles of the disclosure. Retractor system  100  is highly customizable and modular. For example, the primary retractor assembly  200  may be used as a standalone retractor system without the use of secondary retractor assembly  300 . Secondary retractor assembly  300  is configured to couple and uncouple on as needed basis with the primary retractor assembly  200  and secondary retractor assembly  300  can, for example, use one or two arms each having a corresponding blade. 
     Exemplary embodiments may include a primary retractor assembly  200  configured to open and close a first arm  105  and a second arm  107  along a first path of travel. The first path may be an arcuate path or segment defined by the length and geometry of the arms  105  and  107  and a handle pivoting mechanism  101   c  (see  FIG. 8 ) configured to enable first handle  101   a  and second handle  101   b  to open and close. Other paths of travel are contemplated depending upon the geometry of the arms  105 ,  107  and the relative location of the handle pivoting mechanism  101   c . The primary retractor assembly  200  may include a handle assembly having first and second handles  101   a ,  101   b  that are operably coupled to the first and second arms  105 ,  107  and configured to open and close the first and second arms  105 ,  107 . For example, the first handle  101   a  may be coupled to the first arm  105  and the second handle  101   b  may be coupled to the second arm  107 . The first and second arms  105 ,  107  may be operably coupled to first and second pivoting members  105   a ,  107   a  at a distal end thereof, respectively. The first and second pivoting members  105   a ,  107   a  may be configured to operably couple to first and second blades,  205 ,  207  (see  FIG. 2 ), respectively, by a corresponding blade attachment mechanism as will be explained in more detail below during the discussion of  FIGS. 9-13B . 
     In the exemplary embodiment, a first actuator  105   b  and a second actuator  107   b  are configured to adjust the angulation of first blade  205  and second blade  207 , respectively. For example, the first actuator  105   b  may be configured to actuate the first pivoting member  105   a  to adjust the angulation of first blade  205  with respect to the first arm  105 . Similarly, the second actuator  107   b  may be configured to actuate the second pivoting member  107   a  to adjust the angulation of second blade  207  with respect to second arm  107 . In the exemplary embodiment, the first pivoting member  105   a  may be configured to independently adjust the angulation of first blade  205  with respect to the first arm  105  upon actuation of the first actuator  105   b . Similarly, the second pivoting member  107   a  may be configured to independently adjust the angulation of the second blade  207  with respect to the second arm  107  upon actuation of the second actuator  107   b . In disclosed embodiments, the first and second pivoting members  105   a ,  107   a  may each include a corresponding pin and socket mechanism enabling the pivoting members to pivot on a pin aperture  199  (see, e.g.,  FIG. 8 ). Additionally, the first and second pivoting members  105   a ,  107   a  may each include a corresponding blade attachment mechanism at a distal end thereof which will be explained in more detail below when discussing  FIGS. 9-13 . 
     In the exemplary embodiment, the primary retractor assembly  200  may include a primary actuator  102  that is configured to actuate a primary pinion gear mechanism  210  (see  FIG. 7 ) to provide a precise and controlled mechanical advantage to open and close the first arm  105  and second arm  107 . For example, the primary pinion gear mechanism  210  may include a primary pinion gear  210   a  fixedly coupled to the primary actuator  102  such that the primary actuator  102  may rotationally translate the primary pinion gear  210   a . The primary pinion gear  210   a  may be engaged with the secondary pinion gear  210   b , e.g., the primary pinion gear  210   a  and secondary pinion gear  210   b  may be toothed gears that are meshed with one another at a contact location (not illustrated). Furthermore, secondary pinion gear  210   b  may be fixedly coupled to tertiary pinion gear  210   c  which may be axially aligned with secondary pinion gear  210   b  and disposed directly beneath secondary pinion gear  210   b  (see  FIG. 8 ). For example, secondary pinion gear  210   b  may share an axis of rotation with tertiary pinion gear  210   c  and secondary pinion gear  210   b  may be relatively larger in diameter than tertiary pinion gear  210   c . This arrangement may resemble a two stage gear box or the like that allows for an increase in applied torque. In other embodiments, primary pinion gear mechanism  210  may be any other similar planetary gear system as would be understood by a person having ordinary skill in the relevant art. For example, those with skill in the relevant art will readily recognize that the particular diameter, tooth sizing, and tooth spacing of the primary pinion gear  210   a  relative to the particular diameter, tooth sizing, and tooth spacing of the secondary pinion gear  210   b  relative to tertiary pinion gear  210   c  may control the amount of force (mechanical advantage or torque) that is applied to open and close the first and second arms  105 ,  107 . 
     In the exemplary embodiment of  FIG. 8 , tertiary pinion gear  210   c  may be meshed with a first curved rack portion  210   a - 2  and a second curved rack portion  210   b - 2  disposed opposite the first curved rack portion  210   a - 2 . First curved rack portion  210   a - 2  may be fixedly coupled to second arm  101   b  and second curved rack portion  210   b - 2  may be fixedly coupled to first arm  101   a . Each of curved rack portions  210   a - 2  and  210   b - 2  may feature a plurality of teeth extending along the curved body thereof and facing tertiary pinion gear  210   c . The first curved rack portion  210   a - 2  and second curved rack portion  210   b - 2  may be meshed with the teeth of tertiary pinion gear  210   c  on opposite sides of tertiary pinion gear  210   c . In this way, when primary actuator  102  is rotated, primary pinion gear  210   a  rotates which in turn rotates secondary pinion gear  210   b  and tertiary pinion gear  210   c . In turn, tertiary pinion gear  210   c  engages teeth on each of curved rack portions  210   a - 2  and  210   b - 2  and causes handles  101   a ,  101   b  to open or close. In the disclosed embodiment, when tertiary pinion gear  210   c  applies force to first curved rack portion  210   a - 2 , the first curved rack portion  210   a - 2  may extend through first handle  101   a  at a corresponding first handle aperture  210   a - 1 . Similarly, when tertiary pinion gear  210   c  applies force to second curved rack portion  210   b - 2 , the second curved rack portion  210   b - 2  may extend through second handle  101   b  at a corresponding second handle aperture  210   b - 1 . 
     In disclosed embodiments, the primary pinion gear mechanism  210  may be operably coupled to the first and second handles  101   a ,  101   b  and configured to simultaneously open and close the first and second arms  105 ,  107  along a first path of travel. For example, the primary actuator  102  may rotationally translate the primary pinion gear mechanism  210  in a clockwise direction which in turn rotationally translates the first arm  105  and second arm  107  such that they move away from one another, i.e., they open as explained above. Likewise, the primary actuator  102  may rotationally translate the primary pinion gear mechanism  210  in a counter clockwise direction which in turn rotationally translates the first arm  105  and second arm  107  such that they move towards one another, i.e., they close as explained above. Also as explained above, the particular diameter of primary, secondary, and tertiary pinion gears  210   a ,  210   b , and  210   c  may be adjusted to provide the desired amount of mechanical advantage or torque to open and close first and second arms  101   a ,  101   b.    
     In disclosed embodiments, primary retractor assembly  200  may include a primary retention lever  104  disposed between the first and second handles  101   a ,  101   b  that is configured to engage the primary retractor assembly  200  to control opening and closing of the first and second arms  105 ,  107  and thereby retain the first and second arms  105 ,  107  in a specific position. In the disclosed embodiment, primary retention lever  104  may frictionally engage curved rack portion  210   b - 2  to control opening and closing of the first and second arms. In other embodiments, the primary retention lever  104  may engage the primary pinion gear mechanism  210  at an outside portion of the circumference of the primary pinion gear  210   a  (see  FIG. 7 ) to thereby control and/or prevent rotation of the primary pinion gear  210   a . For example, the primary retention lever  104  may lock the primary pinion gear mechanism  210  in place to control opening and closing of the first and second arms. In some embodiments, the primary retention lever  104  may have a biasing element (not illustrated) that causes the primary retention lever  104  to naturally urge an angled tip portion of the body of the primary retention lever  104  against a portion of the primary pinion gear mechanism  210 . For example, a spring may naturally urge an angled tip portion of primary retention lever  104  to engage with a toothed portion of secondary pinion gear  210   b . Additionally, the primary retention lever  104  may be moved from an engagement position where primary retention lever  104  is in direct contact with the primary pinion gear mechanism  210  to a disengaged position where primary retention lever  104  is not engaged with the primary pinion gear mechanism  210 . For example, an end user such as a surgeon may depress primary retention lever  104  with their thumb to toggle primary retention lever  104  between the engaged position and the disengaged position. Furthermore, some embodiments may have a toggle feature (not illustrated) for maintaining the primary retention lever  104  in either of the engaged or disengaged positions. 
     In disclosed embodiments, the primary retractor assembly  200  may include a first table mount portion  106   a  disposed adjacent the first handle  101   a  and coupled to a body  200   a  (see  FIG. 5 ) or housing of the primary retractor assembly  200 . Similarly, the primary retractor assembly  200  may include a second table mount portion  106   b  disposed adjacent the second handle  101   b  and coupled to the body or housing of the primary retractor assembly  200 . The first and second table mount portions  106   a ,  106   b  may each be attached to a surgical table (not illustrated) for fixing the primary retractor assembly  200  (and/or the retractor system  100 ) in a fixed location in three dimensional space. In example embodiments, the primary retractor assembly  200  may be attached to a surgical table by at least one of the first and second table mount portions  106   a ,  106   b  or by both. 
     At least one advantage of securing the primary retractor assembly  200  to a surgical table may be for enhanced stability and the even transfer of resultant forces from the primary actuator  102  through the first and second arms  105 ,  107  to the first and second blades  205 ,  207  and vice versa. For example, when the primary retractor assembly  200  is fixed to the surgical table and the primary actuator  102  is translated to open the first and second arms  105 ,  107  the primary pinion gear mechanism  210  may apply a precise controlled amount of force to open the first and second arms  105 ,  107  to thereby gently retract the tissue of a patient in a controlled manner. Additionally, when the primary retractor assembly  200  is fixed to the surgical table, it may be easier for an end user to independently move only one of the handles  101   a ,  101   b  with respect to the surgical table. When moving only one of the handles  101   a ,  101   b  the corresponding arm  105 ,  107  may move relative to the other. This scenario and functionality may assist a surgeon with precise surgical techniques where it may be desirable to independently move either of the first and second arms  105 ,  107  along the first path of travel independently with respect to the other. 
     Disclosed embodiments described above may be configured to independently open and close the first arm  105  along the first path of travel by movement of the first handle  101   a  relative to the second handle  101   b  and independently open and close the second arm  107  along the first path of travel by movement of the second handle  101   b  relative to the first handle  101   a . Additionally, because the primary pinion gear mechanism  210  includes a primary gear  210   a  and a secondary gear  210   b  operably coupled to the first and second handles  101   a ,  101   b  disclosed embodiments may be configured to provide a controlled mechanical advantage to open and close the first and second arms  105 ,  107  along the first path upon actuation of the primary actuator  102 . 
     In accordance with disclosed embodiments, a secondary retractor assembly  300  may be configured to couple and uncouple from the primary retractor assembly  200  via a first recessed key portion  220   a  disposed on the first arm  105  and a second recessed key portion  220   b  disposed on the second arm  107  (see  FIG. 2 ). Each of recessed key portions  220   a ,  220   b  may include a groove having a geometry that facilitates engagement of the primary retractor assembly  200  with the secondary retractor assembly  300  while also operably allowing the opening and closing of arms  105 ,  107 . For example, the secondary retractor assembly  300  may have a corresponding outdent (e.g., dovetail) on an underside thereof configured to mate with an indent (e.g., dovetail groove) of the primary retractor assembly  200 . Additionally, secondary retractor assembly  300  may be fixed to primary retractor assembly  200  by turnkey  113 . Turnkey  113  may project from a central portion of the primary retractor assembly  200  through a central aperture  113   a  (see  FIG. 6 ) of the secondary retractor assembly  300 . In a first position, turnkey  113  may urge the primary retractor assembly  200  and secondary retractor assembly  300  towards each other and maintain direct contact to fixedly engage them to one another. Conversely, in a second position, turnkey  113  may be rotated such that turnkey  113  is aligned with central aperture  113   a  and therefore has no bearing surface to urge the primary retractor assembly  200  and secondary retractor assembly  300  towards each other. Thus, in the second position the primary retractor assembly  200  and secondary retractor assembly  300  may be disengaged from one another. Other embodiments may use alternate means to securely engage the primary retractor assembly  200  with the secondary retractor assembly  300 , e.g., as fasteners, hexagonal grooves, channel locks, magnets, etc. provided that the primary retractor assembly  200  and the secondary retractor assembly  300  are securely engaged with one another such that resultant forces acting on the retractor system  100  may transfer between primary retractor assembly  200  and secondary retractor assembly  300  and also by extension to a surgical table via table mount portions  106   a  and/or  106   b.    
     Secondary retractor assembly  300  may have a body portion  300   a  generally defining a first channel  109   d  and a second channel  111   d . Secondary retractor assembly  300  may be configured to independently extend and contract a third arm  109  and a fourth arm  111 , respectively. Although two channels  109   d ,  111   d  and two arms  109 ,  111  are illustrated it is contemplated that secondary retractor assembly  300  may have any number of suitable channels and arms. Additionally, it is contemplated that only a single arm, e.g., third arm  109  or fourth arm  111  will be provided in some surgical settings. 
     In disclosed embodiments, the secondary retractor assembly  300  may include a first channel  109   d  having a curved or arcuate shape for operably retaining third arm  109  therein where third arm  109  has a corresponding curved or arcuate shape. The third arm  109  may be configured to extend outwards from first channel  109   d  and contract within first channel  109   d . Similarly, secondary retractor assembly  300  may include a second channel  111   d  having a curved or arcuate shape for operably retaining fourth arm  111  therein where fourth arm  111  has a corresponding curved or arcuate shape. The fourth arm  111  may be configured to extend outwards from first channel  111   d  and contract within second channel  111   d . The geometry of the first channel  109   d  and third arm  109  may define a second path of travel, e.g., an arcuate path of travel defined by the arcuate shapes of the first channel  109   d  and third arm  109 . Similarly, the geometry of the second channel  111   d  and fourth arm  111  may define a third path of travel, e.g., an arcuate path of travel defined by the arcuate shapes of the second channel  111   d  and fourth arm  111 . 
     In disclosed embodiments, the secondary retractor assembly  300  may include a third actuator  109   c  operably disposed adjacent the first channel  109   d  and operably configured to extend and contract the third arm  109  via a pinion gear mechanism (not illustrated) having the same or similar components as primary pinion gear mechanism  210  of primary retractor assembly  200 . For example, a toothed pinion P 1  (see  FIG. 7 ) may be coupled to actuator  109   c  and may operably engage a corresponding rack portion (not illustrated) on an adjacent surface of arm  109  to linearly translate, e.g., curvo-linear, third arm  109  forward and backward, i.e., extend and withdraw or translate away from the operative corridor. Similarly, the secondary retractor assembly  300  may include a fourth actuator  111   c  operably disposed adjacent the second channel  111   d  and operably configured to extend and contract the fourth arm  111  via a pinion gear mechanism (not illustrated) having the same or similar components as primary pinion gear mechanism  210  of primary retractor assembly  200 . For example, a toothed pinion P 2  (see  FIG. 7 ) may be coupled to actuator  111   c  and may operably engage a corresponding rack portion (not illustrated) on an adjacent surface of arm  111  to linearly translate, e.g., curvo-linear, fourth arm  111  forward and backward, i.e., extend and withdraw or translate away from the operative corridor. For example, actuator  109   c  may rotationally translate P 1  in a clockwise direction which in turn linearly translates the third arm  109  arm such that it extends outward from channel  109   d . Similarly, actuator  109   c  may rotationally translate P 1  in a counter clockwise direction which in turn linearly translates the third arm  109  arm such that it contracts inward into channel  109   d . Likewise, actuator  111   c  may rotationally translate P 2  in a clockwise direction which in turn linearly translates the fourth arm  111  arm such that it extends outward from channel  111   d . Similarly, actuator  111   c  may rotationally translate P 2  in a counter clockwise direction which in turn linearly translates the fourth arm  111  such that it contracts inward into channel  109   d . Accordingly, in disclosed embodiments, the third arm  109  is configured to independently extend and contract along a second path of travel upon actuation of the third actuator  109   c , and the fourth arm  111  is configured to independently extend and contract along a third path of travel upon actuation of the fourth actuator  111   c.    
     In disclosed embodiments, the third and fourth arms  109 ,  111  may be operably coupled to third and fourth pivoting members  109   a ,  111   a  at a distal end thereof, respectively. The third and fourth pivoting members  109   a ,  111   a  may be configured to operably couple to third and fourth blades  209 ,  211 , respectively (see  FIG. 3 ) by a corresponding blade attachment mechanism as will be explained in more detail below during the discussion of  FIGS. 9-13B . In the exemplary embodiment, a fifth actuator  109   b  and a sixth actuator  111   b  are configured to adjust the angulation of third blade  209  and fourth blade  211 , respectively. For example, the fifth actuator  109   b  may be configured to actuate the third pivoting member  109   a  to adjust the angulation of third blade  209  with respect to the third arm  109 . Similarly, the sixth actuator  211   b  may be configured to actuate the fourth pivoting member  211   a  to adjust the angulation of fourth blade  211  with respect to fourth arm  111 . In the exemplary embodiment, the third pivoting member  109   a  may be configured to independently adjust the angulation of third blade  209  with respect to third arm  109  upon actuation of the fifth actuator  109   b . Similarly, the fourth pivoting member  211   a  may be configured to independently adjust the angulation of fourth blade  211  with respect to the fourth arm  111  upon actuation of the fourth actuator  111   b.    
     In disclosed embodiments, the third and fourth pivoting members  209   a ,  211   a  may each include a corresponding pin and socket mechanism enabling the pivoting members  209   a ,  211   a  to pivot on a pin disposed in a corresponding pin aperture  199  (see, e.g.,  FIG. 8 ). Additionally, the third and fourth pivoting members  209   a ,  211   a  may each include a corresponding blade attachment mechanism at a distal end thereof which will be explained in more detail below when discussing  FIGS. 9-13 . 
     In disclosed embodiments, the secondary retractor assembly  300  may include a first retention lever  109   e  configured to engage the third arm  109  to control extension and contraction of the third arm  109  along the second path of travel and a second retention lever  111   e  configured to engage the fourth arm  111  to control extension and contraction of the fourth arm  111  along the third path of travel. First and second retention levers  109   e ,  111   e  may have the same or similar components as described above with respect to primary retention lever  104 . 
     First retention lever  109   e  and second retention lever  111   e  may frictionally engage with the third arm  109  and fourth arm  111 , respectively, to control and/or prevent the extension and contraction of the third arm  109  and fourth arm  111 . For example, first retention lever  109   e  and second retention lever  111   e  may engage with a rack portion on an outside adjacent surface of the third arm  109  and fourth arm  111 , respectively, through an aperture  302  (see  FIG. 8 ) projecting through a portion of channels  109   d ,  111   d , respectively. In some embodiments, first and second retention levers  109   e ,  111   e  may include a biasing element having the same or similar components as explained above with respect to primary retention lever  104 . In some embodiments, first retention lever  109   e  may engage a corresponding pinion gear mechanism operably associated with actuator  109   c  to thereby control and/or prevent rotation of the corresponding pinion gear mechanism. Similarly, second retention lever  111   e  may engage a corresponding pinion gear mechanism operably associated with actuator  109   c  to thereby control and/or prevent rotation of the corresponding pinion gear mechanism. 
     Referring generally to  FIGS. 1, 7, and 9-11  the pivoting members  105   a ,  107   a ,  109   a , and  111   a  may each include the same or similar components and features. For example, pivoting members  105   a ,  107   a ,  109   a , and  111   a  may each include a corresponding pin and socket mechanism. The pin and socket mechanism of pivoting members  105   a ,  107   a ,  109   a , and  111   a  may be adjustable by way of actuators  105   b ,  107   b ,  109   b , and  111   b  such that an inclination of pivoting members  105   a ,  107   a ,  109   a , and  111   a  may be independently adjustable with respect to arms  105 ,  107 ,  109 , and  111 , respectively. In some embodiments, translation of actuators  105   b ,  107   b ,  109   b , and  111   b  may cause a corresponding element, such as an internal pin, set screw or the like, to urge pivoting members  105   a ,  107   a ,  109   a , and  111   a  to pivot outwards on a corresponding pin within a corresponding socket thereby enabling travel of pivoting members  105   a ,  107   a ,  109   a , and  111   a  inwards and outwards with respect to arms  105 ,  107 ,  109 , and  111 , respectively. In some embodiments, pivoting members  105   a ,  107   a ,  109   a , and  111   a  may pivot outwards, for example, within a range of 0-25 degrees, and more particularly within a range of 0-15 degrees with respect to arms  105 ,  107 ,  109 , and  111 . 
     Pivoting members  105   a ,  107   a ,  109   a , and  111   a  may include corresponding blade attachment mechanisms  105   f ,  107   f ,  109   f , and  111   f , respectively (see  FIG. 7 ). The blade attachment mechanisms  105   f ,  107   f ,  109   f , and  111   f , may each include a dovetail groove having a geometry that facilitates secure engagement with a corresponding one of blades  205 ,  207 ,  209 , and  211 . For example, blade attachment mechanisms  105   f ,  107   f ,  109   f , and  111   f , may have an indent portion on an inside surface thereof facilitating secure engagement with an outdent portion disposed on an outside surface of blades  205 ,  207 ,  209 , and  211  respectively. In some embodiments, the dovetail grooves of the blade attachment mechanisms  105   f ,  107   f ,  109   f , and  111   f , are tapered, and may for example be conically tapered, from one end to the other end to further securely retain blades  205 ,  207 ,  209 , and  211 . In other embodiments, the blade attachment mechanisms  105   f ,  107   f ,  109   f , and  111   f , may take alternate shapes, and have varying configurations provided that the shape thereof can securely engage with a corresponding one of blades  205 ,  207 ,  209 , and  211 . For example, an indent such as a square channel, hexagonal channel, or the like dimensioned to match to a corresponding outdent. Additionally, the blade attachment mechanisms  105   f ,  107   f ,  109   f ,  111   f  may have an outdent portion (rather than an indent portion as illustrated) and blades  205 ,  207 ,  209 , and  211  may have an indent portion (rather than an outdent portion as illustrated). 
     Referring generally to  FIGS. 9-13B  exemplary blades, shims, and dilators for use with, e.g., retractor system  100 , are disclosed. Referring to  FIGS. 9-11 , an exemplary blade, e.g., first blade  205  is illustrated. It shall be understood that characteristics of first blade  205  may be found throughout each of blades  205 ,  207 ,  209 , and  211  and the foregoing description is described with respect to first blade  205  solely for convenience of explanation. Moreover, although first blade  205  is illustrated as a relatively long and narrow curved blade  205  it can take any shape suitable for any particular type of surgery application. Indeed, it is contemplated that retractor system  100  is suitable for a multitude of different blades having different lengths, widths, and cross-sectional shapes thereof that can couple and uncouple to secondary blades, tools, and shims. For example, relatively shorter and wider blades having generally planar surfaces are contemplated. Furthermore, blade  205  may feature any number or type of secondary coupling members where shims, for example, may couple thereto. In at least one embodiment, blade  205  may have a relatively narrow portion at one end and fan out to a relatively wider portion at the opposite end, i.e., the blade  205  may have a width that increases along the length thereof from one end to the other end. Additionally, blade  205  may include channels, grooves, indents, outdents, etc. for fixation of secondary members such as shims, light fixtures other diagnostic tools such as endoscopes, electrodes, temperature sensors, suction devices, and etc. 
     In the exemplary embodiment, blade  205  has a proximate side  205   a , a distal side  205   b  opposite the proximate side, an outside surface  205   c  and an inside surface  205   d  opposite the outside surface  205   c . The proximate side  205   a  may be operably coupled to a distal end of pivoting member  105   a  via an engagement feature  205   e  disposed on the outside surface  205   c  of blade  205 , for example. In some embodiments, blade  205  may include an elastic material allowing it to deflect at least partially. Additionally, in some embodiments a blade removal instrument may be required to install and/or remove blade  205  from a blade attachment mechanism. 
     In the disclosed embodiment, engagement feature  205   e  is the outdent portion of a dovetail groove, i.e., the dovetail. In other embodiments, engagement feature  205   e  may be a lap joint, tongue and groove type joint, a doweled butt joint, etc. In the exemplary embodiment, engagement feature  205   e  features an indent portion  205   f . Indent portion  205   f  may be a socketed portion facilitating secured engagement and retention with blade attachment mechanism  105   f . For example, indent portion  205   f  may house a spring clip (not illustrated) to hold blade  205  in secure engagement with blade attachment mechanism  105   f . In embodiments that include a spring clip, a corresponding release tool or lever may be inserted into the indent portion  205   f  to release the biasing force of the spring and thereby uncouple the blade  205  from blade attachment mechanism  105   f . In other embodiments, engagement feature  205   e  may have an aperture for running a diagnostic tool such as an electrode or endoscope there through. In some embodiments, blade  205  may be conductive such that it may communicate with an external diagnostic tool (not illustrated). For example, blades may include a conductive material such as a metal like copper and be conductive and/or have terminals for electrical conduction between conductive pads placed external to retractor system  100 . In some embodiments, blade  205  may include partially conductive features, e.g., a semiconductor and/or other passive electrical devices such as resisters, diodes, and etc. In other embodiments, blade  205  may be an insulator such that it does not interfere with electrical signal processing of the aforementioned electrical devices. 
     In the exemplary embodiment, first blade  205  may include a longitudinal groove  205   g  extending longitudinally along the inside surface  205   d  that is sized accordingly to house and retain a corresponding pin  205   p  therein. In at least one embodiment, pin  205   p  may securely attach to a vertebra of a patient&#39;s spine by socketing in to the vertebrae or screwing into the vertebrae. In some embodiments, pin  205   p  may be a conductive pin having a sensor at a distal end thereof or pin  205   p  may be a hollow pin that houses electrical components and wiring therein. In other embodiments pin  205   p  is purely mechanical in nature. In at least one embodiment, pin  205   p  may be used to facilitate attachment of a shim  205   s  to an inside surface  205   d  of blade  205 . Shim  205   s  may laterally extend from a side surface of the blade  205  and include a gripping portion at a proximate side thereof. Shim  205   s  may also extend from the blade  205  to increase the operative length thereof and/or extend laterally to increase the operative width thereof. In some embodiments, the first, second, third, and fourth blades  105 ,  107 ,  109 ,  111  are each configured to operably couple to a corresponding first, second, third, and fourth shim laterally projecting from a side portion thereof. In other embodiments, diagnostic tools such as an electrode, endoscope, fiber optic, light emitting diode or the like may extend along groove  205   g . In other embodiments still, a second groove (not illustrated) similar to groove  205   g  may be provided so that a combination of the above described features may be used. For example, groove  205   g  may house a corresponding pin  205   p  and the second groove (not illustrated) may enable a diagnostic tool or the like to extend along the second groove (not illustrated). 
     Referring to  FIG. 12  an exemplary set of nested dilators  400  is illustrated. Exemplary dilators  400  may include a neuro monitoring sensor or the like to help guide insertion of the dilators through muscle fibers. The set of nested dilators  400  may include a series of dilators having alternating circular and ellipsis (oval) cross sectional shapes or oblong cross-sectional shapes. For example, a first dilator  401  having a relatively small circular cross section is surrounded by a second dilator  403  having an ellipsis, or oval shaped cross section. The size and shape of the circular cross section of the first dilator  401  may be defined by a radius extending from a center point thereof and the shape of the ellipsis cross section may be defined by a major axis and a minor axis extending perpendicularly with respect to one another from a center point thereof. 
     In the exemplary embodiment, the second dilator  403  may, for example, have an ellipsis or elliptical cross section, or other cross sections, for example bi-convex or elongated and substantially flat sides with convex ends, and may have a curvature but may not be circular or elliptical, some such embodiments having a minor axis roughly corresponding to the radius of the circular cross section of first dilator  401 . For example, the minor axis of the ellipsis cross section of the second dilator  403  may only be slightly larger than the radius of the circular cross section of the first dilator  401 , and the major axis of the ellipsis cross section of the second dilator  403  may be relatively larger than the radius of the circular cross section of the first dilator  401  and the minor axis of the ellipsis cross section of the second dilator  403 . In some embodiments, the major axis of the ellipsis cross section of second dilator  403  may be roughly twice as large as the radius of the circular cross section of first dilator  401 . In some embodiments, the major axis of the ellipsis cross section of the second dilator  403  may be twice as large as the minor axis of the ellipsis cross section of the second dilator  403 . At least one advantage to this arrangement of alternating cross sections is that the second dilator  403  may be insert around the first dilator  401  between fibers of a muscle, e.g., the paraspinous muscle, such that the major axis of the second dilator  403  is initially arranged parallel with the fibers of the paraspinous muscle and can therefore be insert around the first dilator  401 . Once inserted around the first dilator  401 , second dilator  403  can be rotated such that the major axis of second dilator  403  is perpendicular to the orientation of the fibers of the paraspinous muscle thereby gently separating the fibers by orienting the second dilator  403  such that the major axis area of the second dilator  403  gently and controllably applies pressure to separate the fibers. 
     A third dilator  405  having a circular cross section may be insert around the second dilator  403 . The size and shape of the circular cross section of the third dilator  405  may be defined by a radius extending from a center point thereof. For example, the third dilator  405  may have a circular cross-sectional shape having a radius roughly corresponding to the major axis of the second dilator  403 . The third dilator  405  can freely rotate around the second dilator  403  and features a circular cross section having a radius that is only slightly larger than the cross-sectional major axis of the second dilator  403 . A fourth dilator  407  having an ellipsis cross section (oval) may be insert around the third dilator  405 . The fourth dilator  407  may be defined by an ellipsis cross section having a minor axis that is only marginally larger than the cross sectional radius of the third dilator  405 , i.e., the cross sectional minor axis of the fourth dilator roughly corresponds to the cross sectional radius of the third dilator  405 . Additionally, the cross-sectional major axis of the fourth dilator  407  is relatively larger than the cross sectional radius of the third dilator  405  and the cross sectional minor axis of the fourth dilator. In some embodiments, the major axis of the ellipsis cross section of fourth dilator  407  may be roughly twice as large as the radius of the circular cross section of third dilator  405 . In some embodiments, the major axis of the ellipsis cross section of the fourth dilator  407  may be twice as large as the minor axis of the ellipsis cross section of the fourth dilator  407 . At least one advantage to this arrangement of alternating cross sections is that the fourth dilator  407  may be insert around the third dilator  405  between fibers of a muscle, e.g., the paraspinous muscle, such that the major axis of the fourth dilator  407  is initially arranged parallel with the fibers of the paraspinous muscle and can therefore be insert around the third dilator  405 . Once inserted around the third dilator  405 , fourth dilator  407  can be rotated such that the major axis of fourth dilator  407  is perpendicular to the orientation of the fibers of the paraspinous muscle thereby gently separating the fibers by orienting the fourth dilator  407  such that the major axis area of the fourth dilator  407  gently and controllably applies pressure to separate the fibers. 
       FIG. 13A  is a top down view of the set of nested dilators  400  as explained above. As illustrated a set of nested dilators  400  that may sequentially gently separate fibers of a muscle are illustrated. The set of nested dilators  400  may be insert sequentially and rotated on an as needed basis to gently dilate an anatomical feature.  FIG. 13B  is a top down view of blades  205 ,  207 ,  209 , and  211 . As illustrated blades  205 ,  207  are relatively larger in width than blades  209 , and  211 . 
       FIGS. 14-19  illustrate various positions and modes of operation of retractor system  100  in use with the set of nested dilators  400 . For example, in  FIG. 14 , retractor system  100  is shown in a closed position where arms  105 ,  107  are closed and surround, at least partially, the set of nested dilators  400 . Additionally, arms  109 ,  111  are fully extended and surround, at least partially, the set of nested dilators  400 . In  FIG. 14 , the inside surfaces of blades  205 ,  207 ,  209 , and  211  (not labelled in  FIG. 14 ) together surround and contact an outside surface of a fourth dilator  407  (not labelled in  FIG. 14 ). For example, the blades  205 ,  207 ,  209 , and  211  surround and contact a set of nested dilators  400 . For example still, a side surface of each of blades  205 ,  207 ,  209 , and  211  contacts an adjoining side surface of a different adjacent blade of the blades  205 ,  207 ,  209 , and  211  thereby forming a closed shape.  FIG. 17  is a side view of the arrangement of  FIG. 14 . 
     In  FIG. 15 , the set of nested dilators  400  is removed and the retractor system  100  is adjusted to a first partially opened position where arms  105 ,  107  are partially opened and arms  109 ,  111  are partially contracted.  FIG. 18  is a side view of the first partially opened arrangement of  FIG. 15 . In  FIG. 16 , the retractor system is adjusted to a second partially opened position where arms  105 ,  107  are further opened and arms  109 ,  111  are further contracted.  FIG. 18  is a side view of the second partially opened arrangement of  FIG. 16 .  FIG. 19  shows the angulation of each blade being adjusted outward approximately 15 degrees from the side view of  FIG. 18 . 
     Additional Retractor Embodiments 
     Referring generally to  FIGS. 20-81  an example modular retractor system including a modular retractor  500  and various add on retractor modules  600 ,  700 ,  800 ,  900 ,  1000 , and  1100  for use with modular retractor  500  are disclosed. In some embodiments, modular retractor  500  may include the same, substantially the same, and/or similar components and functionality as primary retractor  100  and the associated blades, dilators, and secondary retractor assembly  300 . Accordingly, those with skill in the art will understand the general principles, modes of operation, and associated methods of each example embodiment may be combined and/or modified in view of the skill of a person of ordinary skill in the art. 
     With reference to  FIGS. 20-28C  a modular retractor  500  for enabling access to a surgical site, an adjustment tool  10 , a table mount  70 , and a table mount rack module  60  are disclosed.  FIGS. 20-21  are perspective views of a modular retractor  500  and  FIG. 22  is a top down view of the modular retractor  500  showing various axes and directions of operation.  FIG. 23  is a perspective view of an adjustment tool  10  for use with disclosed modular retractor  500  embodiments.  FIGS. 24-25  are exploded parts views of a modular retractor  500 .  FIGS. 26A-26E  are various views of a distraction mechanism  50  for use with disclosed modular retractor  500  embodiments.  FIGS. 27A and 27B  are various views of a modular retractor  500  coupled to a table mount  70 .  FIGS. 28A-28C  are various views of a table mount rack module  60 . 
     Modular retractor  500  is highly customizable and may be considered modular for reasons that will be readily apparent and explained in further detail below. For example, the modular retractor  500  may be used as a standalone retractor system without the use of additional add on modules or modular retractor  500  may be used with any of the disclosed modules discussed herein unless the context clearly suggests otherwise. 
     Modular retractor  500  may be configured to distract and retract a first arm  505  along a path of travel and a second arm  507  along a different path of travel. The various paths of travel may be an arcuate path or segment defined by the length and geometry of the arms  505  and  507 , respectively, and a handle pivoting mechanism  515  (see  FIG. 26D ). Handle pivoting mechanism  515  may be configured to enable first handle  501   a  and second handle  501   b  to open and close, for example. Handle pivoting mechanism  515  may be a pin, screw, or the like, for example. Other paths of travel than those specifically shown are contemplated and those paths of travel may depend upon the geometry of the arms  505 ,  507  and the relative location of the handle pivoting mechanism  515 . The modular retractor  500  may include a handle assembly having first and second handles  501   a ,  501   b  that are removably coupled to the first and second arms  505 ,  507  and configured to open and close the first and second arms  505 ,  507 . For example, the first handle  501   a  may be coupled to the first arm  505  and the second handle  501   b  may be coupled to the second arm  507 . Additionally, the arms  505 ,  507  may extend through side channels of the body  503 , respectively, and/or be pivotable relative to body  503  and/or be operably coupled to body  503 . In various embodiments, the first handle  501   a  and second handle  501   b  may be removed and are held in place by first handle connection pin  508   a  and second handle connection pin  508   b , for example. In various embodiments, the connection pins  508   a ,  508   b  may be a pin, screw, knob, turnkey, and/or retaining fastener that a surgeon may quickly remove to uncouple the handle  501   a ,  501   b , for example. Furthermore retractor  500  may include a table mount  506  extending in the lateral direction from body  503 . At least one advantage of having the first and second handles  501   a ,  501   b  be removable is greater freedom in performing a surgery due to the reduced structure adjacent a target surgical location, for example. For example still, after a surgeon has retracted a patient tissue, the surgeon may remove the handles  501   a ,  501   b  to prevent bumping into them. 
     In various embodiments, the first and second arms  505 ,  507  may be coupled to first and second pivoting members  505   a ,  507   a  at a distal end thereof, respectively. The first and second pivoting members  505   a ,  507   a  may be configured to operably couple to first and second blades,  40  (see  FIG. 22 ), respectively, by a corresponding blade attachment mechanism  505   c ,  507   c  as will be explained in more detail below. In the example embodiment, a first actuator  505   b  and a second actuator  507   b  are configured to adjust the angulation of first blade  40  and second blade  40 , respectively. For example, the first actuator  505   b  may be configured to actuate the first pivoting member  505   a  to adjust the angulation of first blade  40  with respect to the first arm  505 . Similarly, the second actuator  507   b  may be configured to actuate the second pivoting member  507   a  to adjust the angulation of second blade  40  with respect to second arm  507 . In the example embodiment, the first pivoting member  505   a  may be configured to independently adjust the angulation of first blade  40  with respect to the first arm  505  upon actuation of the first actuator  505   b . Similarly, the second pivoting member  507   a  may be configured to independently adjust the angulation of the second blade  40  with respect to the second arm  507  upon actuation of the second actuator  507   b . In disclosed embodiments, the first and second pivoting members  505   a ,  507   b  may each include a corresponding pin and socket mechanism enabling the pivoting members to pivot on a pin aperture  199  (see, e.g.,  FIG. 8 ). 
     As shown in  FIG. 22 , modular retractor  500  may extend in a longitudinal direction from a proximal end  500   p  to a distal end  500   d  in a longitudinal direction (or proximal-to-distal direction) parallel to longitudinal axis A-A. Additionally, modular retractor  500  may extend in a lateral direction (or widthwise direction) parallel to lateral axis B-B. The longitudinal axis A-A may be perpendicular to the lateral axis B-B and intersect at body  503  at a medial location of retractor  500 , for example. In various embodiments, and as shown by the Cartesian coordinate system in  FIG. 22A , the longitudinal direction may be understood as the X direction and the lateral direction may be understood as the Y direction. Furthermore, a depth and/or thickness of modular retractor may be understood as the Z direction or vertical direction when viewed in a plan view. 
       FIG. 23  is a perspective view of an adjustment tool  10  for use with disclosed modular retractor  500  embodiments. In the example illustration, adjustment tool  10  may include a drive end  11  and a handle end  12 , for example. Drive end  11  may have a size and shape configured to rotate various actuators of modular retractor  500 , for example. In various embodiments, drive end  11  may take the shape of a hexolobular drive end, a hex drive end, a torx drive end, a polygonal drive end, a square drive end, or the like. Similarly, actuators  502 ,  507   b ,  505   b  may take any corresponding shape, for example. 
       FIG. 24  is a top down exploded parts view of a modular retractor  500  and  FIG. 25  is a perspective exploded parts view of a modular retractor  500 . In the example embodiment, arm  505  may include a rack portion  505   d  at a distal end thereof and arm  507  may include a rack portion  507   d  at a distal end thereof, for example. In various embodiments, rack portions  505   d ,  507   d  may be curved and be disposed at different relative distances from the distal end of the respective handle  505 ,  507 , for example. Additionally rack portions  505   d ,  507   d  may be meshed with and movable by distraction mechanism  50 , for example. Distraction mechanism  50  may be operably drivable by actuator  502 , for example. Distraction mechanism  50  may include a plurality of gears to provide a mechanical advantage to open and close the arms  505 ,  507  as will be explained in further detail below. 
       FIGS. 26A-26E  are various views of a distraction mechanism  50  for providing a mechanical advantage to distract and retract arms  505 ,  507 . Distraction mechanism  50  may principally be formed of a plurality of spur gears  51 ,  52 ,  54 ,  55 , and a partial spur gear  57  that are meshed together and sized appropriately for providing a mechanical advantage to distract and/or retract arms  505 ,  507 . For example, primary actuator  502  may be connected to first spur gear  51  and second spur gear  52  by shaft  53 , for example. In the example embodiment, primary actuator  502 , spur gears  51 ,  52 , and shaft  53  are coaxially aligned in the vertical direction. Additionally, a partial spur gear  57  may attached to shaft  53 . Partial spur gear  57  may be understood as a portion and/or slice of a relatively large spur gear having a central axis of rotation coincident with shaft  53 , for example. In the example embodiment, partial spur gear  57  may have an axis of rotation coincident with shaft  53 , for example. Additionally, first spur gear  51  may be meshed with third spur gear  54 . In turn, third spur gear  54  may be connected to fourth spur gear  55  by shaft  56 . Third spur gear  54 , shaft  56 , and fourth spur gear  55  may be coaxially aligned. In the example embodiment, third spur gear  54  is a relatively large spur gear and fourth spur gear  55  is a relatively small spur gear. Those with skill in the art will understand this arrangement may be advantageous for providing a relatively great mechanical advantage to perform distraction and/or retraction of arms  505 ,  507 , for example. In the example embodiment, fourth spur gear  55  may be meshed with partial spur gear  57 . In this way, distraction mechanism  50  may comprise a plurality of spur gears having various teeth and recesses that are meshed and/or interconnected to one another. 
       FIG. 26B  is a top perspective view of a distraction mechanism  50  and  FIG. 26C  is an enlarged top perspective view of distraction mechanism  50  with some parts removed for ease of understanding. In the example embodiment, third spur gear  54  may include teeth  54   a  symmetrically radially disposed on a side surface around the circumference of third spur gear  54  and a rack  54   b  may be radially disposed on a top surface of third spur gear  54  proximate the edge of spur gear  54 , for example. Primary pawl  504  may be configured to engage circular rack  54   b  to allow spur gear  54  to rotate in a first direction (counter clockwise direction) and prevent third spur gear  54  from rotating in a second direction (clockwise direction). For example, primary pawl  504  may be disposed on a pivoting hinge and be biased such that a hook portion may be pushed downward against rack  54   b  such that the hook portion is meshed within a valley between any pair of the teeth of rack portion  54   b , for example. In operation, an end user may rotate primary actuator  502  (via tool  10 , e.g.) counter clockwise such that primary pawl  504  moves in and out of the various valleys between teeth of rack portion  54   b . Notably, due to pawl  504  being biased against rack  54   b , pawl  504  may prevent third spur gear  54  from rotating in the clockwise direction. For example, as arms  505 ,  507  are opened patient tissue may apply a closing force attempting to push arms  505 ,  507  back towards a closed position and pawl  504  may prevent and/or suppress arms  505 ,  507  from moving into a closed position. Additionally, in various embodiments pawl  504  may be depressible at a lateral end thereof opposite the hook portion that is engaged with rack  54   b  such that the hook portion of pawl  504  is moved upward in the vertical direction and prevented from engaging with rack  54   b  such that arms  505 ,  507  may be closed if and when desired. Furthermore, in  FIG. 26C  it is shown that spur gear  52  is meshed with rack portion  505   d  of arm  505  and rack portion  507   d  of arm  507 . For example, rack portion  507   d  is meshed with a distal side of spur gear  52  and rack portion  505   d  is meshed with a proximate side of spur gear  52 . Accordingly, rotation of spur gear  52  in a first direction will cause arms  505 ,  507  to distract outward by an equal amount and rotation of spur gear  52  in a second direction opposite the first direction will cause arms  505 ,  507  to retract inward by an equal amount. Alternatively, an end user may squeeze handles  501   a ,  501   b  to cause distraction and/or retraction by an equal amount which will also cause rotation of the various gears of distraction mechanism  50 . 
       FIG. 26D  is a bottom perspective view of distraction mechanism  50  and  FIG. 26E  is an enlarged bottom perspective view of distraction mechanism  50 . In the example embodiment, the underside of partial spur gear  57  is shown as being meshed with spur gear  55  and being rotatably engaged with drive shaft  53 . Additionally, suitable cutout portions  505   z ,  507   z  may be provided in the first handle  505  and second handle  507  that allow partial spur gear  57  to rotate a suitable distance when expanding arms  505 ,  507  such that partial spur gear  57  is fully contained within body  503  and does not clash with handles  505 ,  507 , for example. 
       FIG. 27A  is a top down view of a modular retractor  500  coupled to a table mount rack module  60  which is in turn coupled to a table mount  70 .  FIG. 27B  is a perspective view of a modular retractor  500  coupled to a table mount rack module  60  which is in turn coupled to a table mount  70 . In the example embodiment, the table mount  70  may be connected to and rigidly supported by a surgeons table via table mount portion  73 , for example. Arms  72  and  71  may be adjustable by way of adjustment knob  74  to position table rack module  60  at a suitable location, for example. 
       FIGS. 28A and 28B  are perspective views of a table mount rack module  60 .  FIG. 28C  is an exploded parts view of table mount rack module  60 . In the example embodiment, table mount rack module  60  may include an aperture  64  having a size and shape that corresponds to a size and shape of table mount arm  506  of modular retractor  500 , for example. Depressible lever  65  may be used to lock table mount arm  506  when table mount arm  506  is insert inside of aperture  64 , for example as shown in  FIGS. 27A and 27B . Additionally, table mount arm  506  may slide in and out of aperture  64  to facilitate positioning modular retractor  500 , for example. Table mount module  60  may include a connection arm  63 , which may be insert into a corresponding aperture of table mount  70 , for example as shown in  FIGS. 27A and 27B  to secure table mount rack module  60  to table mount  70 . Connection arm  63  may be rigidly secured to body portion  66 , for example. Additionally, extendable arm  67  may slide forward and backward through body  66  by a rack and pinion mechanism. For example, actuators  61 ,  62  may be securely coupled to body  66  and may each have pinion portions  61   a ,  62   a  having teeth that engage with rack portion  67   a  of extendable arm  67 . Accordingly, rotation of actuator  61  and/or actuator  62  may rotate pinion portions  61   a  and/or  62   a  such that teeth of pinion portions  61   a ,  62   a  cause extendable arm  67  to move forward and/or backward depending on the direction actuators  61  and/or  62  are rotated. Additionally, table mount rack module  60  may include a pawl  68  having a first hook portion  68   a  and/or a second hook portion  68   b , for example. Pawl  68  may be pivotally coupled to body portion  66  at a pivot location  66   b  by a pin, for example. Pivot location  66   b  may enable pawl  68  to be toggled between a first position where pawl  68  allows extendable arm  67  to move forward but prevents extendable arm  67  from moving backward in the opposite direction. Similarly, in various embodiments, pawl  68  may be toggled to a second position where pawl  68  allows extendable arm  67  to move backward but prevents extendable arm  67  from moving forward. In some embodiments, pawl  68  may be moved to a third position, in the middle of the first position and second position, where pawl  68  prevents extendable arm  67  from moving forward and backwards. For example, in some embodiments, and in a third position pawl  68  may lock extendable arm  67  from relative motion in the forward and backwards direction. Other embodiments may utilize a locking element (not illustrated) to secure extendable arm  67  in an appropriate position. In this way, table rack module  60  may facilitate the relative motion of modular retractor  500  forward and backward in a direction defined by axis D-D of extendable arm  67 . Additionally, table rack module  60  may facilitate the relative motion of modular retractor  500  from side to side in a direction defined by an extension direction C-C of table mount  506  (see  FIG. 22 ), for example. 
     Referring generally to  FIGS. 29-34  a first module  600  is disclosed.  FIGS. 29 and 30  are top perspective views of a first module  600  and  FIGS. 31A and 31B  are bottom perspective views of a first module  600 .  FIG. 32  is an exploded parts view of a first module  600  and  FIGS. 33A-34  are various perspective views of first module  600  coupled to modular retractor  500 . 
     In accordance with disclosed embodiments, first module  600  may be configured to couple and uncouple from modular retractor  500  at connection points  503   a , for example (see  FIG. 20 ). In various embodiments, the first module  600  may have at least one corresponding connection point  603   a  on an underside thereof (see  FIG. 31A ) configured to couple, connect, and/or mate with a connection point  503   a  of the modular retractor  500 . In the example embodiment, connection points  503   a  are indented apertures and connection points  603   a  are outdented posts having a corresponding size and shape to one another, respectively. In some embodiments, connection points  503   a ,  603   a , may have slotted rails and/or grooves to facilitate a connection and/or prevent rotation of first module  600  relative to modular retractor  500 , for example. Similarly, and in the example embodiment, one connection point of connection points  603   a  may be shaped like a circular post and the other connection point  603   a  may be shaped like an oval post to facilitate mating the first module  600  with modular retractor  500  in an appropriate orientation. Additionally, first module  600  may be locked to modular retractor  500  by lock  513  (see  FIG. 20 ). Lock  513  may be pivotable such that in a locked position a flange portion of lock  513  may pivot into a locking aperture  603   e  of first module  600 , for example. Similarly, in an unlocked position the flange portion of lock  513  may be unseated from aperture  603   e . Other embodiments may use alternate means to securely engage the modular retractor  500  with the first module  600 , e.g., as fasteners, hexagonal grooves, channel locks, magnets, etc. provided that the modular retractor  500  and the first module  600  are securely engaged with one another such that resultant forces acting on the modular retractor  500  may transfer between modular retractor  500  and first module  600 . 
     First module  600  may include a first arm  605  and a second arm  607  that extend through body  603 . First arm  605  may extend through body  603  through a first contoured channel  603   b  and second arm  607  may extend through body  603  through a second contoured channel  603   c , for example (see  FIG. 32 ). In various embodiments, contoured channels  603   b ,  603   c  may be L shaped channels. First module  600  may be configured to independently extend first arm  605  along a first path of travel and independently extend second arm  607  along a second path of travel by independent rack and pinion mechanisms, for example. The first path and second path may be an arcuate path or segment defined by the length and geometry of the arms  605  and  607 , for example. In various embodiments, the first path and second path may symmetrically fan out with respect to one another. Other paths of travel than those specifically shown are contemplated, e.g., a linear path. 
     First module  600  may include a table mount  606  extending laterally from a side surface thereof. Table mount  606  may facilitate the relative motion of first module  600  (and/or modular retractor  500  when coupled thereto) from side to side in a direction defined by an extension direction E-E of table mount  606  (see  FIG. 34 ), for example. Table mount  606  may be securely coupled to sliding frame  608 . Sliding frame  608  may be configured to slide forward and backward through sliding frame aperture  603   d  of body  603 , for example (see  FIG. 32 ). Additionally, in various embodiments, sliding frame  608  may be configured to support first and second arms  605 ,  607  at a bottom surface of first and second arms  605 ,  607  proximate first pivoting member  605   a  and second pivoting member  607   a , respectively (see  FIGS. 31A and 31B ). In various embodiments, support portion  609  may be pivotable relative to sliding frame  608  by pivot point  609   a , for example. In various embodiments, the first arm  605  may include first post  605   f  and second arm  607  may include second post  607   f  that extend through corresponding slotted apertures  609   b , respectively, of support portion  609 . In this way, and due in part to the size and geometry of the slotted apertures  609   b , support portion  609  may support both first arm  605  and second arm  607  while also enabling first and second arms  605 ,  607  to be independently movable relative to one another, for example. In some embodiments, pivot point  609   a  may be replaced by a non pivoting fastener such that first arm  605  and second arm  607  are not independently movable relative to one another (not illustrated) and distract and retract by equal amounts. 
     First module  600  may be configured to extend first arm  605  by activation of actuator  601 , e.g., by rotation of actuator  601 . Actuator  601  may be securely attached to body portion  603  and include a pinion portion  601   a  (pinion gear and/or spur gear) having teeth that engage with and are meshed with curved rack portion  605   d  disposed on a side surface of first arm  605 , for example. Accordingly, rotation of actuator  601  may rotate pinion portion  601   a  such that teeth of pinion portion  601   a  causes first arm  605  to move forward and/or backward depending on the direction actuator  601  is rotated. Additionally, first module  600  may include a first pawl  604   a  that may be configured to engage the curved rack portion  605   e  disposed on a top surface of first arm  605 , for example. First pawl  604   a  may be configured to allow pinion portion  601   a  to rotate in a first direction (counter clockwise direction) and prevent pinion portion  601   a  from rotating in a second direction (clockwise direction). For example, first pawl  604   a  may be disposed on a pivoting hinge and be biased by a spring or the like such that a hook portion may be pushed downward against rack  605   e  such that the hook portion is meshed within a valley between any pair of the teeth of rack portion  605   e , for example. In operation, an end user may rotate actuator  601  (via tool  10 , e.g.) counter clockwise such that pawl  604   a  moves in and out of the various valleys between teeth of rack portion  605   e  while first arm  605  extends outward away from body  603 . Notably, due to pawl  604   e  being biased against rack portion  605   e , pawl  604   a  may prevent first arm  605  from being pushed in an opposite direction. For example, as arm  605  is distracted outward patient tissue may apply a closing force attempting to push arm  605  back towards body  603  and pawl  604   a  may prevent and or suppress this closing force. Additionally, in various embodiments pawl  604   a  may be depressible at a lateral end thereof opposite the hook portion that is engaged with rack  605   e  such that the hook portion of pawl  604   a  is moved upward in the vertical direction and prevented from engaging with rack  605   e  such that arm  605  may be closed if and when desired. 
     First module  600  may be configured to extend second arm  607  by activation of actuator  602 , e.g., by rotation of actuator  602 . Actuator  602  may be securely attached to body portion  603  and include a pinion portion  602   a  (pinion gear and/or spur gear) having teeth that engage with and are meshed with curved rack portion  607   d  disposed on a side surface of second arm  607 , for example. Accordingly, rotation of actuator  602  may rotate pinion portion  602   a  such that teeth of pinion portion  602   a  causes second arm  607  to move forward and/or backward depending on the direction actuator  602  is rotated. Additionally, first module  600  may include a second pawl  604   b  that may be configured to engage the curved rack portion  607   e  disposed on a top surface of second arm  607 , for example. Second pawl  604   b  may operate in the same, substantially the same, and/or similar manner as explained above with respect to first pawl  604   a . Accordingly, duplicative description will be omitted. 
     In various embodiments, the first and second arms  605 ,  607  may be coupled to first and second pivoting members  605   a ,  607   a  at a distal end thereof, respectively. The first and second pivoting members  605   a ,  607   a  may be configured to operably couple to third blade  45  and fourth blade  45 , respectively, by a corresponding blade attachment mechanism  605   c ,  607   c . In the example embodiment, a first blade actuator  605   b  and a second blade actuator  607   b  are configured to adjust the angulation of blades  45  respectively (see  FIG. 34 ). For example, the first blade actuator  605   b  may be configured to actuate the first pivoting member  605   a  to adjust the angulation of blade  233  with respect to the first arm  605 . Similarly, the second actuator  607   b  may be configured to actuate the second pivoting member  607   a  to adjust the angulation of blade  234  disposed therein with respect to second arm  607 . In the example embodiment, the first pivoting member  605   a  may be configured to independently adjust the angulation of a blade with respect to the first arm  605  upon actuation of the first actuator  605   b . Similarly, the second pivoting member  607   a  may be configured to independently adjust the angulation of a second blade with respect to the second arm  607  upon actuation of the second actuator  607   b . In disclosed embodiments, the first and second pivoting members  605   a ,  607   a  may each include a corresponding pin and socket mechanism enabling the pivoting members to pivot, for example. 
     Referring generally to  FIGS. 35-40  a second module  700  for use with modular retractor  500  is disclosed.  FIGS. 35-36  are various top perspective views of a second module  700  and  FIGS. 36-37  are various bottom perspective views of a second module  700  for use with disclosed modular retractor  500  embodiments.  FIG. 39  is an exploded parts view of a second module  700  and  FIG. 40  is a top down view of a second module coupled to modular retractor  500  and a plurality of blades. 
     In accordance with disclosed embodiments, second module  700  may be configured to couple and uncouple from modular retractor  500  at connection points  503   a , for example (see  FIG. 20 ). For example, the second module  700  may have at least one corresponding connection point  703   a  on an underside thereof (see  FIG. 38 ) configured to couple, connect, and/or mate with a connection point  503   a  of the modular retractor  500  in the same, similar, and/or substantially the same manner as explained above. Accordingly, duplicative description will be omitted. Additionally, second module  700  may be locked to modular retractor  500  by lock  513  (see  FIG. 20 ). Lock  513  may be pivotable such that in a locked position a flange portion of lock  513  may pivot into a locking aperture  703   e  of second module  700 , in the same, similar, and/or substantially the same manner as explained above. Accordingly, duplicative description will be omitted. 
     Second module  700  may include an arm  705  that extends through body  703 . Arm  705  may extend through body  703  through a first contoured channel  703   b . Second module  700  may be configured to extend arm  705  along a path of travel by a rack and pinion mechanism, for example. The path of travel may be an arcuate path or segment defined by the length and geometry of arms  705 , for example. Other paths of travel than those specifically shown are contemplated, e.g., a linear path. 
     Second module  700  may include a table mount  706  extending laterally from a side surface thereof. Table mount  706  may facilitate the relative motion of second module  700  (and/or modular retractor  500  when coupled thereto) from side to side in a direction defined by an extension direction F-F of table mount  706  (see  FIG. 40 ), for example. Table mount  706  may be securely coupled directly to arm  705  (see  FIG. 39 ), for example. Second module  700  may be configured to extend arm  705  by activation of actuator  701 , e.g., by rotation of actuator  701 . Actuator  701  may be securely attached to body portion  703  and include a pinion portion  701   a  (pinion gear and/or spur gear) having teeth that engage with and are meshed with curved rack portion  705   d  disposed on a side surface of arm  705 , for example. Accordingly, rotation of actuator  701  may rotate pinion portion  701   a  such that teeth of pinion portion  701   a  cause arm  705  to move forward and/or backward depending on the direction actuator  701  is rotated. Additionally, second module  700  may include a first pawl  704  that may be configured to engage the curved rack portion  705   e  disposed on a top surface of arm  705 , for example. First pawl  704  may be configured to allow pinion portion  701   a  to rotate in a first direction (counter clockwise direction) and prevent pinion portion  701   a  from rotating in a second direction (clockwise direction) in the same, similar, and/or substantially the same manner as previously explained. Accordingly, duplicative description will be omitted. 
     In various embodiments, arm  705  may be coupled to pivoting member  705   a  at a distal end thereof. Pivoting member  705   a  may be configured to operably couple to a blade  35  by blade attachment mechanism  705   c . In the example embodiment, blade actuator  705   b  may be configured to adjust the angulation of blade  35  (see  FIG. 40 ). For example, the blade actuator  705   b  may be configured to actuate the first pivoting member  705   a  to adjust the angulation of blade  35  with respect to arm  705 . In disclosed embodiments, the first pivoting member  705   a  may include a corresponding pin and socket mechanism enabling pivot member  705   a  to pivot, for example. 
     Referring generally to  FIGS. 41A-44  a third module  800  for use with the modular retractor  500  is disclosed.  FIG. 41A  is a top perspective view of a third module  800  and  FIG. 41B  is a bottom perspective view of a third module  800 .  FIG. 42  is an exploded parts view of a third module  800 .  FIG. 43  is a perspective view of a third module  800  coupled to a modular retractor  500  and  FIG. 44  is a perspective view of a third module  800  coupled to a modular retractor  500  and a plurality of blades. 
     In accordance with disclosed embodiments, third module  800  may be configured to couple and uncouple from modular retractor  500  at connection points  503   a , for example (see  FIG. 20 ). For example, the third module  800  may have at least one corresponding connection point  803   a  on an underside thereof (see  FIG. 41B ) configured to couple, connect, and/or mate with a connection point  503   a  of the modular retractor  500  in the same, similar, and/or substantially the same manner as previously explained. Accordingly, duplicative description will be omitted. Additionally, third module  800  may be locked to modular retractor  500  by lock  513  (see  FIG. 20 ). Lock  513  may be pivotable such that in a locked position a flange portion of lock  513  may pivot into a locking aperture  803   e  of third module  800 , in the same, similar, and/or substantially the same manner as previously explained. Accordingly, duplicative description will be omitted. 
     Third module  800  may include an arm  805  that includes a straight portion  810  and a C shaped curved portion  811 . Straight portion  810  of arm  805  may extend through body  803  and move forward and backward in a longitudinal direction, for example. As seen best in  FIG. 43 , when third module  800  is coupled to modular retractor  500  the C shaped curved portion  811  extends laterally outward in a lateral direction B-B farther than the farthest lateral edge of arm  807 . For example, the C shaped curved portion  811  does not obscure a surgeons viewing area and/or access to a surgical site. Furthermore, third module  800  may orient and/or support a blade  35  such that the blade faces the body portion  803  of third module  800 , the body portion of modular retractor  500 , and is also symmetrically disposed relative to the first arm  505  and second arm  507  of modular retractor  500 . For example, the C shaped curved portion  811  may support a blade  35  at a distal most position that is aligned in the longitudinal axis A-A of modular retractor  500  (see  FIG. 43 ). The straight portion  810  of arm  805  may extend through body  803  through a first contoured channel. In various embodiments, the contoured channel  803   b  may be an L shaped channel, for example. Third module  800  may be configured to extend arm  805  along a path of travel by a rack and pinion mechanism, for example. The path of travel may be linear path, for example. Other paths of travel than those specifically shown are contemplated, e.g., an arcuate path. 
     Third module  800  may include a table mount  806  extending laterally from a side surface thereof in a direction defined by an extension direction G-G of table mount  806  (see  FIG. 43 ), for example. Table mount  806  may facilitate the secure placement of third module  800  such that third module  800  remains fixed in 3D space and/or facilitate the relative motion of third module  800  (and/or modular retractor  500  when coupled thereto) in any direction when moving table mount  70 , for example. Third module  800  may be configured to extend arm  805  by activation of actuator  801 , e.g., by rotation of actuator  801 . Actuator  801  may be securely attached to body portion  803  and include a pinion portion  801   a  (pinion gear and/or spur gear) having teeth that engage with and are meshed with straight rack portion  805   d  disposed on a side surface of arm  805 , for example. Accordingly, rotation of actuator  801  may rotate pinion portion  801   a  such that teeth of pinion portion  801   a  cause arm  805  to move forward and/or backward depending on the direction actuator  801  is rotated in the same, similar, and/or substantially the same manner as previously explained. Accordingly, duplicative description will be omitted. Additionally, third module  800  may include a first pawl  804  that may be configured to engage rack portion  805   e  disposed on a top surface of arm  805 , for example. First pawl  804  may be configured to allow pinion portion  801   a  to rotate in a first direction (counter clockwise direction) and prevent pinion portion  801   a  from rotating in a second direction (clockwise direction) in the same, similar, and/or substantially the same manner as previously explained. Accordingly, duplicative description will be omitted. 
     In various embodiments, curved arm portion  811  of arm  805  may be coupled to blade attachment mechanism  805   c  at a distal most end. The curved arm portion  811  may support blade attachment mechanism  805   c  such that it faces modular retractor  500  and is aligned with the longitudinal axis A-A of modular retractor  500  (see  FIG. 43 ). In the example embodiment, blade attachment mechanism  805   c  is fixed and a corresponding blade  35  does not pivot and/or angulate. However in other embodiments, third module  800  may include a first blade actuator (not illustrated) that is configured to adjust the angulation of a corresponding blade and a corresponding pivoting member with the same, substantially the same, and/or similar structural and characteristics as explained herein with respect to other embodiments. 
     Third module  800  may include a table mount  806  extending in a first lateral direction along axis G-G from arm  805  and a module mount  809  extending in a second lateral direction along axis H-H from arm  805 . i.e., in an opposite lateral direction (see  FIG. 43 ). For example, table mount  806  may extend to the left direction and module mount  809  may extend to the right direction. Additionally, straight portion  810  of arm  805  may be supported by body  803  on the left side of the longitudinal axis A-A of modular retractor  500 . In this configuration, the module mount  809  may cross over the longitudinal axis A-A, for example. Module mount  809  may support a free hand module  900 , as will explained in further detail below. 
     Referring generally to  FIGS. 45A-45B  an alternative third module  800   a  embodiment is disclosed. Third module  800   a  may include the same, substantially the same, and/or similar components and functionality as third module  800 . Accordingly, duplicative description will be omitted. In the example embodiment, third module  800   a  may be modified such that table mount  806  and module mount  809  are aligned. For example, table mount  806  and module mount  809  each extend from arm  805  in opposite directions and are aligned on the same common extension axis. For example still, axis G-G of table mount  806  and axis H-H of module mount  809  are aligned and extend in opposite directions. 
     Alternative third module  800   a  may include a locking actuator  850 , for example. Locking actuator  850  may be rotatably secured within body portion  803  and be disposed above straight portion  810  of arm  805 , for example. In various embodiments, locking actuator  850  may include an outside thread pattern corresponding to an inside thread pattern of body  803  (not illustrated). In various embodiments, locking actuator  850  may be rotated in a first direction such that locking actuator  850  advances towards straight portion  810  of arm  805 . As locking actuator  850  advances, a bottom portion of locking actuator  850  may contact an upper surface of straight portion  810  of arm  805  and apply a downward force to straight portion  810 . In this way, locking actuator  850  may provide a frictional force against straight portion  810  of arm  805  thereby preventing and/or suppressing arm  805  from moving forward and backward. For example, the greater the downward force applied to straight portion  810 , the greater the frictional force between the underside of locking actuator  850  and the upper surface of straight portion  810 . At least one advantage of locking actuator  850  may be that arm  805  may be locking in position such that it is fixed and is prevented from moving forward and backward, for example. In various embodiments, this may assist a surgeon in placement of third module  800  and/or modular retractor  500 . For example, a surgeon may lock arm  805  via locking actuator  850  and position modular retractor  500  and third module  800  as desired while arm  805  remains in place. Thereafter, the surgeon may release locking actuator  850  and extend arm  805  to distract patient tissue or retract arm  805 . Additionally, in some surgical settings, it may be advantageous to allow third module  800  to remain in a distracted position (while third module  800  is coupled to a table mount via table mount arm  806 ) and remove modular retractor  500  while the surgical site remains distracted, or at least partially distracted, by third module  800 , for example. Additionally, any of the various disclosed modules may include a locking actuator  850  rotatably disposed in a corresponding body portion above a corresponding arm and work in the same, substantially the same, and/or similar manner as explained above. 
     In other embodiments, locking actuator  850  may be rotated between a locked position and an unlocked position. For example, in various embodiments, locking actuator  850  may include at least one locking tooth (not illustrated) that is disposed within locking cutout  850   a  of arm  805 . For example, at least one locking tooth may jam with rack portion  805   d  and prevent arm  805  from moving, for example. In other embodiments, locking actuator  850  may include at least one locking tooth that jams with pinion portion  801   a , for example. In other embodiments, locking actuator  850  may lock pawl  804  such that pawl  804  is engaged with rack portion  805   e  and prevented from pivoting up and down relative to rack portion  805   e . For example, by locking pawl  804  in place such that pawl  804  is engaged with rack portion  805   e , arm  805  may be prevented from moving forward and backward. Moreover, the above described embodiments and functionality of locking actuator  850  are broadly applicable to all of the disclosed embodiments herein. For example, any of the various modules disclosed herein may include a locking actuator  850  having at least one locking tooth that jams with a corresponding rack portion of an arm, and/or a pinion portion of an actuator as explained above. 
     Referring generally to  FIGS. 46-54  a free hand module  900  and a telescoping blade  20  for use with the modular retractor  500  and/or free hand module  900  is disclosed.  FIG. 46  is a perspective view of a free hand module  900  and  FIGS. 47A and 47B  are side views of a free hand module  900  for use with disclosed modular retractor  500  embodiments.  FIG. 48A  is an exploded parts view of a free hand module  900  and  FIG. 48B  is a removed parts view of free hand module  900 .  FIGS. 49A-49B  are various perspective views of a free hand module  900  in various configurations.  FIGS. 50-51  are various perspective views of a free hand module  900  and a telescoping blade system  20 .  FIG. 52A  is a perspective view of a blade connection channel  905   d  and  FIG. 52B  is a perspective view of a blade fastener.  FIGS. 53-54  are various perspective views of a third module  800  coupled to a modular retractor  500  and a free hand module  900  coupled to the third module  800 . 
     In accordance with disclosed embodiments, free hand module  900  may be configured to couple and uncouple from third module  800  (see  FIG. 46 ). For example, the free hand module  900  may be configured to couple, connect, and/or mate with module mount  809 . In the example embodiment, gripping arms  916  may grip onto module mount  809 , for example. Additionally, gripping arms  916  may include a plurality of rails and channels extending in the lateral direction on an inside surface thereof. The rails of gripping arms  916  may have a size and shape corresponding to rails and channels of module mount  809 , for example. Accordingly, the gripping arms  916  may securely mate with module mount  809  by seating rails of gripping arms  916  in the channels of module mount  809  and seating the rails of module mount  809  in the channels of gripping arms  916 . Furthermore, the gripping arms  916  may provide a clamping force against module mount  809  securely coupling the free hand module  900  to third module  800 , for example. 
     In various embodiments, free hand module  900  may be configured to enable a surgeon to freely extend blade  20  forward and backward in the longitudinal direction along longitudinal axis A-A, for example. Free hand module  900  may not include a rack and pinion mechanism to extend the blade  20  and may rely on the manual operability of a surgeon, for example. In some surgical contexts, a free hand module  900  may afford a surgeon greater freedom in installation and facilitate the surgeon in retracting delicate patient tissue by hand. For example, when performing a retraction step with free hand module  900 , patient tissue may resist the retraction and/or opening of a surgical access site. The degree of resistance of the patient tissue may be sensed by the surgeon as a form of haptic feedback informing the surgeon how much pressure has been applied to the patient tissue. In this way, the surgeon can sense and or prevent applying to much retraction force to a patient tissue and/or applying just the right amount of retraction force in delicate situations. Similarly, a free hand module  900  may be relatively easier for a surgeon to manipulate than a rack and pinion type of motion. This may allow the surgeon to quickly retract specific patient tissue with greater freedom in operation. Additionally, a length and/or height of telescoping blade  20  may be adjustable. Accordingly, a surgeon can retract various layers of patient tissue that are below (or above) the patient tissue which has been previously retracted by the other blades. 
     Free hand module  900  may include a handle  901  at a proximal end and a blade attachment mechanism  905   c  at a distal end, for example. Handle  901  may be rigidly secured to a shaft  905  and shaft  905  may define a longitudinal axis of free hand module  900 , for example. Free hand module  900  may include a moving mechanism  910 . As illustrated best in  FIGS. 48A and 48B , moving mechanism  910  may include various components that enable an end user to toggle a lever  911  to enable the forward and backward movement of handle  901 , shaft  905 , and blade attachment mechanism  905   c  relative to moving mechanism  910  and module mount  809 , for example. Moving mechanism  809  may include a body portion  913  having an aperture  913  extending therethrough. Shaft  905  may extend through aperture  913   a  and slotted aperture  915   b  of gripper body  915 , for example. An upper portion of lever support  912  may be disposed above body  913  and be operably coupled to lever  911  while a lower portion including an annular channel  912   b  may be disposed within body  913 . For example, lever support  912  may be securely attached to lever  911  by laterally extending posts  912   a  that extend through corresponding apertures  911   a  of lever  911 . In this way, lever  911  may be pivotable about posts  912   a  and when depressed an upper surface of body  913  may act as a support surface such that depressing lever  911  pulls lever support  912  upward. For example, lever support  912  may be pivotable up and down in the vertical direction by depressing and/or rotating lever  911 . For example still, pressing down on lever  911  may pull lever support  912  upward relative to body  913 . Additionally, the lower portion of lever support  912  disposed within body  913  may prevent the over rotation of lever support  912  due to suitable retaining rails of body  913  being inset within annular ring  912   b  such that lever support  912  is fixedly retained by body  913 , for example. 
     As shown best in  FIGS. 48A-48B , an uppermost coupling portion  915   a  of gripper body  915  may be secured within a lower cavity of lever support  912 . In this way, when lever  911  is actuated and pulls lever support  912  upwards, lever support  912  also pulls gripper body  915  upwards. In various embodiments, a stop block  914  may be disposed within body  913  at a bottom portion thereof. Stop block  914  may be disposed beneath shaft  905 , for example. Additionally, stop block  914  may include inclined surfaces that may bias gripping arms  916  inwards (towards one another) to provide a gripping force against module mount  809 , for example. In operation, an end user may actuate lever  911  such that gripper body  915  is pulled upwards and gripping arms  916  are biased inwards towards one another to securely couple to module mount  806  via clamping force. 
     In various embodiments, free hand module  900  via lever  911  may be adjustable and/or fixed in three modes of operation, for example. In a first mode of operation, and when lever  911  is in a first position, shaft  905  is extendable forward and backward through body  913  and gripping arms  916  are in an open position (see  FIG. 49A ). When gripping arms  916  are in an open position free hand module  900  may be positioned in place around and/or above module mount  809 . In the first mode of operation, moving mechanism  910  and gripping arms  916  are both fully open, for example. In a second mode of operation, and when lever  911  is in a second position, shaft  905  is extendable forward and backward through body  913  and gripping arms  916  are in a closed position whereby gripping arms  916  provide a suitable clamping force to module mount  809 . In the second mode of operation, moving mechanism  910  is movable in the longitudinal direction and free hand module  900  is securely coupled to module mount  809  due to gripping arms  916  being in the closed position, for example. In a third mode of operation, and when lever  911  is in a third position, shaft  905  is not extendable forward and backward through body  913  and gripping arms  916  are in a closed position (see  FIG. 49B ). In the third mode of operation, moving mechanism  910  is fixed relative to shaft  905  and free hand module  900  is fixed in 3D space due to gripping arms  916  being in the closed position and securely clamped on to module mount  809  (see  FIGS. 53-54 ). 
     With reference to  FIGS. 50-52B , a telescoping blade  20  is disclosed. Telescoping blade  20  may securely connect to blade attachment mechanism  905   c  of free blade module  900 , for example. Additionally, telescoping blade  20  may securely connect to any of the other blade attachment mechanisms disclosed herein. Telescoping blade  20  may include a first blade  22  and a second blade  24  that is extending along axis Z-Z, for example. First blade  22  may include a channel  23  extending longitudinally down a length thereof from proximal end  20   p  to about the distal end  20   d . Similarly, second blade  24  may include a rail  25  extending longitudinally down a length thereof from proximal end  20   p  to about distal end  20   d . In various embodiments, the channel  23  and/or rail  25  may stop and/or terminate before the distal end  20   d  to prevent the second blade  24  from extending too far. In various embodiments, the second blade  24  may slide upward and downward in a proximal-to-distal direction, shown by axis Z-Z in  FIG. 50 . Additionally, an outside surface of blade  22  may include an engagement feature  26  for securely coupling to blade attachment mechanism  905   c , for example. Engagement feature  26  may include two spring loaded tabs  27  that are flexible towards one another and naturally biased away from one another, for example. In various embodiments, an end user may slide engagement feature  26  down into channel  905   d  of blade attachment mechanism  905   c  from above and the two spring loaded tabs  27  may push outward against side surfaces of channel  905   d  to frictionally retain engagement feature  26  therein. Additionally, channel  905   d  may include a stop feature  905   e  adjacent a bottom surface thereof. In various embodiments, the stop feature  905   e  may be a curved bottom surface corresponding to the geometry of the spring loaded tabs  27 , for example. In other embodiments, the two spring loaded tabs  27  may seat into corresponding channels or indents of blade attachment mechanism  905   c  (not illustrated). Furthermore, in other embodiments the engagement feature  26  may be rotated about 180 degrees such that the blade  20  may be insert into blade engagement mechanism  905   c  from below. 
       FIGS. 53-54  illustrate a modular retractor  500  with a third module  800  coupled thereto and a free hand module  900  coupled to the third module  800 . In the example embodiment, the telescoping blade  20  is attached to a distal end of free hand module  900  and blade  30  is attached to the distal end of third module  800 . Additionally, a centerline of telescoping blade  20  and a centerline of blade  30  are aligned with longitudinal axis A-A of modular retractor  500  (see  FIG. 22 ). However, it shall be appreciated that free hand module  900  is slidable along module arm  809  and can be positioned alternately than shown. Furthermore, the curved arm  811  curves out laterally farther than arm  507  of modular retractor  500 . As illustrated, blades  30 ,  40 , and  20  form an opening for a surgical access location and/or a surgical access site. 
       FIGS. 55-56  are various perspective views of a fourth module  1000  for use with disclosed modular retractor  500  embodiments.  FIG. 57  is an exploded parts view of a fourth module  1000 .  FIGS. 58-59  are various views of a fourth module  1000  coupled to a modular retractor  500  and  FIGS. 60-61  are various views of a fourth module  1000  coupled to a first free hand module  900  and a second free hand module  900 . 
     Fourth module  1000  may include the same, substantially the same, and or similar components as third module  800 . Accordingly, duplicative disclosure will be omitted and/or minimized. Fourth module  1000  may be configured to couple and uncouple from modular retractor  500  at connection points  503   a , for example (see  FIG. 20 ). For example, the fourth module  1000  may have at least one corresponding connection point  1003   a  on an underside thereof (see  FIG. 56 ) that is configured to couple, connect, and/or mate with a connection point  503   a  of the modular retractor  500  in the same, substantially the same, and or similar manner as explained above. Additionally, fourth module  1000  may be locked to modular retractor  500  by lock  513  (see  FIG. 20 ). Lock  513  may be pivotable such that in a locked position a flange portion of lock  513  may pivot into a locking aperture  1003   e  of fourth module  1000 , in the same, substantially the same, and or similar manner as explained above. 
     Fourth module  1000  may include an arm  1005  that includes a straight portion  1010  and a C shaped curved portion  1011 . Straight portion  1010  of arm  1005  may extend through body  1003  and move forward and backward in a longitudinal direction, for example. As seen best in  FIG. 58 , when fourth module  1000  is coupled to modular retractor  500  the C shaped curved portion  1011  extends laterally outward in a lateral direction farther than the farthest lateral edge of arm  507  of modular retractor  500 . For example, the C shaped curved portion  1011  does not obscure a surgeons viewing area and/or access to a surgical site. The straight portion  1010  of arm  1005  may extend through body  1003  through an L shaped contoured channel  1003   b , for example. Fourth module  1000  may be configured to extend arm  1005  along a path of travel by a rack and pinion mechanism, for example. The path of travel may be linear path, for example. 
     Fourth module  1000  may include a table mount  1006  extending laterally from a side surface thereof in a direction defined by an extension direction H-H of table mount  1006  (see  FIG. 58 ), for example. Table mount  1006  may facilitate the secure placement of fourth module  1000  such that fourth module  1000  remains fixed in 3D space and/or facilitate the relative motion of fourth module  1000  (and/or modular retractor  500  when coupled thereto) in any direction when moving table mount  70 , for example. Fourth module  1000  may be configured to extend arm  1005  by activation of actuator  1001 , e.g., by rotation of actuator  1001 . Actuator  1001  may be securely attached to body portion  1003  and include a pinion portion  1001   a  (pinion gear and/or spur gear) having teeth that engage with and are meshed with straight rack portion  1005   d  disposed on a side surface of arm  1005 , in the same, substantially the same, and or similar manner as explained above. Additionally, fourth module  1000  may include a first pawl  1004  that may be configured to engage the rack portion  1005   e  disposed on a top surface of arm  1005 , for example. First pawl  1004  may be configured to allow pinion portion  1001   a  to rotate in a first direction (counter clockwise direction) and prevent pinion portion  1001   a  from rotating in a second direction (clockwise direction) in the same, substantially the same, and or similar manner as explained above. 
     Fourth module  1000  may include a table mount  1006  extending in a lateral direction along axis H-H away from arm  1005  and longitudinal axis A-A. Fourth module  1000  may include a proximal module mount  1009  extending along axis I-I in a lateral direction away from arm  1005  towards longitudinal axis A-A. For example, table mount  1006  may extend to the left direction and proximal module mount  1009   p  may extend to the right direction. Additionally, in various embodiments, the C shaped curved portion  1011  may include a distal module mount  1009   d  that extends along axis J-J from a side surface of curved arm portion  1011  such that it crosses over longitudinal axis A-A of modular retractor  500 . The distal module mount  1109   d  and proximal module mount  1009   p  may be symmetrically disposed relative to one another with respect to longitudinal axis A-A, for example (see  FIG. 58 ). Additionally, straight portion  1010  of arm  1005  may be supported by body  1003  on the left side of the longitudinal axis A-A of modular retractor  500 . In this configuration, module mounts  1009   p ,  1009   d  may cross over the longitudinal axis A-A, for example. Module mounts  1009   p ,  1009   d  may each independently support a free hand module  900 , in the same, similar, and/or substantially the same manner as explained previously. For example, as shown in  FIGS. 60-61  proximal module mount  1009   p  supports a free hand module  900  in a proximal position and distal module mount  1009   d  supports a free hand module  900  in a distal position. 
     Referring generally to  FIGS. 62-65  a fifth module  1100  for use with the modular retractor  500  is disclosed.  FIGS. 62-63  are various perspective views of a fifth module  1100  for use with disclosed modular retractor  500  embodiments.  FIG. 64  is an exploded parts view of a fifth module  1100  and  FIG. 65  is a top perspective view of a fifth module  1100  coupled to a modular retractor  500 . 
     Fifth module  1100  may include the same, substantially the same, and or similar components as third module  800  and/or fourth module  1000 . Accordingly, duplicative disclosure will be omitted and/or minimized. Fifth module  1100  may be configured to couple and uncouple from modular retractor  500  at connection points  503   a , for example (see  FIG. 20 ). For example, the fifth module  1100  may have at least one corresponding connection point  1103   a  on an underside thereof (see  FIG. 63 ) that is configured to couple, connect, and/or mate with a connection point  503   a  of the modular retractor  500  in the same, substantially the same, and or similar manner as explained above. Additionally, fifth module  1100  may be locked to modular retractor  500  by lock  513  (see  FIG. 20 ). Lock  513  may be pivotable such that in a locked position a flange portion of lock  513  may pivot into a locking aperture  1103   e  of fifth module  1100 , in the same, substantially the same, and or similar manner as explained above. Similarly, in an unlocked position the flange portion of lock  513  may be unseated from aperture  1103   e.    
     Fifth module  1100  may include an arm  1105  that includes a straight portion  1110  and a C shaped curved portion  1111 . Straight portion  1110  of arm  1105  may extend through body  1103  and move forward and backward in a longitudinal direction, for example. As seen best in  FIG. 65 , when fifth module  1100  is coupled to modular retractor  500  the C shaped curved portion  1111  extends laterally outward in a lateral direction farther than the farthest lateral edge of arm  1105 . For example, the C shaped curved portion  1111  does not obscure a surgeon&#39;s viewing area and/or access to a surgical site. The straight portion  1110  of arm  1105  may extend through body  1103  through an L shaped contoured channel  1103   b . Fifth module  1100  may be configured to extend arm  1105  along a path of travel by a rack and pinion mechanism, for example. The path of travel may be linear path, for example. 
     Fifth module  1100  may include a table mount  1106  extending laterally from a side surface of arm  1105  adjacent a junction of curved portion  1111  and straight portion  1110 . Table mount  1106  may extend along axis H-H in a direction defined by an extension direction of table mount  1106  (see  FIG. 65 ), for example. In the example embodiment, table mount  1106  extends in a perpendicular direction to longitudinal axis A-A and/or a dominant extension direction of straight portion  1110 . Table mount  1106  may facilitate the secure placement of fifth module  1100  such that fifth module  1100  remains fixed in 3D space and/or facilitate the relative motion of fifth module  1100  (and/or modular retractor  500  when coupled thereto) in any direction when moving table mount  70 , for example. Fifth module  1100  may be configured to extend arm  1105  by activation of actuator  1101 , e.g., by rotation of actuator  1101 . Actuator  1101  may be securely attached to body portion  1103  and include a pinion portion  1101   a  (pinion gear and/or spur gear) having teeth that engage with and are meshed with straight rack portion  1105   d  disposed on a side surface of straight portion  1110  of arm  1105 , in the same, substantially the same, and or similar manner as explained above. Additionally, fifth module  1100  may include a pawl  1104  that may be configured to engage the rack portion  1105   e  disposed on a top surface of straight portion  1110  of arm  1105 , for example. Pawl  1104  may be configured to allow pinion portion  1101   a  to rotate in a first direction (counter clockwise direction) and prevent pinion portion  1101   a  from rotating in a second direction (clockwise direction) in the same, substantially the same, and or similar manner as explained above. 
     Fifth module  1100  may include a body  1103  having a curved body portion  1107  extending away from longitudinal axis A-A. In the example embodiment, curved body portion  1107  curves away in an opposite direction from arm  1105  and defines the distal most portion of body  1103 . Curved body portion  1107  may support and orient proximal modular mount  1109  such that it extends in a lateral direction towards arm  1105 , and crosses over longitudinal axis A-A. For example, table mount  1106  may extend to the left direction from a left side of arm  1105  and proximal module mount  1109   p  may extend along axis K-K to the left direction from a left side of curved body portion  1107  and cross over longitudinal axis A-A. Additionally, in various embodiments, the C shaped curved portion  1111  may include a distal module mount  1109   d  that extends from a side surface of curved arm portion  1111  such that it crosses over longitudinal axis A-A of modular retractor  500 . The distal module mount  1109   d  and proximal module mount  1109   p  may be disposed opposite one another and each cross over longitudinal axis A-A, for example. Additionally, straight portion  1110  of arm  1105  may be supported by body  1103  on the left side of the longitudinal axis A-A of modular retractor  500 . Module mounts  1109   p ,  1109   d  may each independently support a free hand module  900 , as explained previously. Furthermore, in various embodiments, module mount  1109   p  may be relatively shorter than module mount  1109   d.    
     Referring generally to  FIGS. 66-75  various blades for use with the modular retractor  500  and any of the various modules disclosed herein are disclosed.  FIG. 66  is a top view of a pair of blades  30 ,  FIG. 67  is a bottom view of a pair of blades  30 , and  FIG. 68  is a perspective view of a pair of blades  30  for use with disclosed modular retractor  500  embodiments. Blades  30  may be shaped like a half circle, for example. Accordingly, in various embodiments when blades  30  adjoin one another they may form a common circle in a fully closed position. Additionally, blades  30  may include an arcuate channel  31  extending along an inside surface thereof from a proximal end (see  FIG. 66 ) to a distal end (see  FIG. 67 ), for example. Arcuate channel  31  may have a size and shape corresponding to a size and shape of an arcuate outdent of a dilator, for example arcuate outdent  90   a  of dilator  90  shown in  FIGS. 80A, 80B . Alternatively, arcuate channel  31  may have a size and shape corresponding to a size and shape of an arcuate outdent of a shim (not illustrated). Additionally, blades  30  may include an aperture  32  extending through a top surface of blade  30  at the proximal end and penetrating the inside surface of blade  30  thereby providing access to the surgical access opening created by blades  30 , for example. Aperture  32  may provide access for light fixtures and other diagnostic tools such as endoscopes, electrodes, temperature sensors, suction devices, and etc. that may be insert therein and be protected while extending through blade  30 , for example. 
       FIG. 69  is an enlarged view of a top portion of a universal blade fastener  33 . Universal blade fastener  33  may be similar to blade fastener  26  of telescoping blade  20  (see  FIG. 52B ) but in reverse. For example, blade fastener  33  may be configured for top loading blade  30  to a blade receiving mechanism. Blade fastener  33  may include a pair of spring loaded tabs  34  adjacent the upper surface of blade  30  and a curved support surface  35  therebelow. For example, spring loaded tabs  34  may be disposed at an upper region of blade fastener  33  and curved support surface  35  may be disposed at a lower portion of blade fastener. In this way, an end user can insert the support surface  35  within a blade receiving mechanism from above and the spring loaded tabs  34  can help retain blade  30  therein by a biasing force applied to sidewalls of a blade receiving mechanism. Furthermore, any other blade disclosed herein may include the same, similar, or substantially the same blade fastener  26 . 
       FIG. 70  is a top view of various blades  40  and  35  and  FIG. 71  is a bottom view of the three blades  40  and  35  for use with disclosed modular retractor  500  embodiments.  FIG. 72  is a perspective view of blades  35 ,  40  for use with disclosed modular retractor  500  embodiments. In the example embodiment, a first blade  40 , second blade  40 , and a third blade  35  may form an oval shape. For example, when blades  40 ,  35  are closed together such that they adjoin one another they may form an oval like shape. Blades  40  may include two arcuate channels  41  and an aperture  42 . Similarly, blade  35  may include two arcuate channels  36  and an arcuate channel  37 . Arcuate channels  41 ,  37  may have a size and shape corresponding to a size and shape of an arcuate outdent of a dilator, for example arcuate outdent  81  of dilator  81  shown in  FIG. 76 . Additionally, in the fully closed position where blades  40 ,  35  adjoin one another, the six arcuate outdents of  FIG. 76  may be disposed in a corresponding relative position and have a corresponding size and shape to the six arcuate channels  36 ,  37  shown in the three blade configuration of  FIG. 70 . 
     Furthermore, blades  40  may include an aperture  42  extending through a top surface of blade  40  at the proximal end and penetrating the inside surface of blade  40  and blade  35  may include an aperture  37  extending through a top surface of blade  35  at the proximal end and penetrating the inside surface of blade  35 . Apertures  37  and  42  may provide access for light fixtures and other diagnostic tools such as endoscopes, electrodes, temperature sensors, suction devices, and etc. that may be insert therein and be protected while extending through blades  35  and  40 , for example. 
       FIG. 73  is a top view of four blades  40 ,  45  and  FIG. 74  is a bottom view of the four blades for use with disclosed modular retractor  500  embodiments.  FIG. 75  is a perspective view of the four blades  40 ,  45  for use with disclosed modular retractor  500  embodiments. In the closed position, blades  40 ,  45  may form an oval like shape. Blade  45  may include an arcuate channel  46  for securing to an arcuate outdent of a dilator having the same, similar, and or substantially the same attributes and purposes as explained above. Additionally blade  45  may include an aperture  47  extending through a top surface of blade  45  at the proximal end and penetrating the inside surface of blade having the same, similar, and or substantially the same attributes and purposes as explained above. 
     Referring generally to  FIGS. 76-81  various dilators for use with the modular retractor  500  and the various blade embodiments disclosed herein are illustrated.  FIG. 76  is a top view of a plurality of nested dilators  80  and  FIG. 77A  is a perspective view of the plurality of nested dilators  80  in a non-nested configuration and  FIG. 77B  is a perspective view of the plurality of nested dilators  80  in a nested configuration. In the example embodiment, five dilators are illustrated having progressively increasing sizing. A first dilator  85  may have a circular shape and a relatively narrow diameter for initiating a dilation process. An outside perimeter of the second dilator  84  may have an oval like shape and an inside diameter of dilator  84  may have a circular like shape corresponding to the outer diameter of first dilator  85 . An outside perimeter of the third dilator  83  may have an oval like shape and an inside perimeter of the third dilator  83  may have an oval like shape corresponding to the outer perimeter of second dilator  84 . Similarly, an outside perimeter of the fourth dilator  82  may have an oval like shape and an inside perimeter of the fourth dilator  82  may have an oval like shape corresponding to the outer perimeter of third dilator  83 . Similarly, an outside perimeter of the fifth dilator  81  may have an oval like shape and an inside perimeter of the fifth dilator  81  may have an oval like shape corresponding to the outer perimeter of fourth dilator  82 . In various embodiments, the dilators may be successively nested within one another to dilate a patient tissue before use of the various disclosed retractor embodiments. Additionally, fifth dilator  81  may include a plurality of arcuate outdents  81   a  (e.g., an arcuate rail or the like) extending along an outside surface thereof. The arcuate outdent  81   a  may mate with an arcuate channel of various blades as disclosed above. 
       FIG. 78  is a top view of a dilator  90  having an oval like outer perimeter and an oval like inner perimeter and  FIG. 79  is a perspective view of dilator  90 . Dilator  90  may include a plurality of arcuate outdents  91   a  (e.g., an arcuate rail or the like) extending along an outside surface thereof. In the example embodiment, arcuate outdents  91   a  are disposed along roughly half of the available radial outer surface and extend in a proximal to distal direction, e.g., about half of the available perimeter includes arcuate outdents  91   a  that extend from the proximal end to distal end. The arcuate outdents  91   a  may mate with an arcuate channel of various blades in the same, similar, and/or substantially the same manner as explained above.  FIG. 80A  is a top view of a dilator  95  and  FIG. 80B  is a perspective view of dilator  95 . Dilator  95  may have a circular outer diameter and a circular inner diameter. Dilator  95  may include a plurality of arcuate outdents  95   a  symmetrically radially disposed along the outer surface. The arcuate outdents  95   a  may mate with an arcuate channel of various blades as disclosed above. 
       FIGS. 80C-80E  show various perspective and elevation views of a set of nested and cylindrically shaped dilators  99 . In the example embodiment, an innermost dilator  98  may be the thinnest and the longest dilator of the set, while the outermost dilator  94  may be the widest and the shortest dilator of the set. Of course the relative length and width of any dilator of the set of dilators  99  may be adjusted consistent with the particular surgery being performed. Additionally, there may be any number and size dilators in between the innermost dilator  98  and outermost dilator  94 , for example first inner dilator  97  and second inner dilator  96 . With reference to  FIGS. 80D and 80E , it is seen that the outside circumferential surface of outermost dilator  94  has a plurality of rail portions  94 A that extend down its length in a proximal to distal direction. The rail portions  94 A generally have a size and shape corresponding to channel portions of various blades disclosed herein. For example, these rail portions  94 A may be disposed in particular locations along the outside circumferential surface of the outermost dilator  94  that takes into account the particular surgical approach employed by the surgeon and the location of the corresponding channel portions of the chosen blades, for example. 
     As seen best in the top down view of  FIG. 81 , rail portions  94 A may be shaped like circular, oval, or arcuate outdents, for example. Additionally, pairs of adjacent rails  94 A may form coupling locations for any of the example blade embodiments disclosed herein. For example, as shown in  FIG. 81  blade  1  and blade  2  may couple to respective pairs of rails  94 A in a first region (approximately upper half area of  FIG. 81 ) and blade  3  may couple to the remaining respective pair of rails  94 A in a second region (approximately lower half area of  FIG. 81 ). The illustrated spacing arrangement of rails  94 A takes into account a specific surgical approach chosen by the surgeon and the functionality of disclosed retractor embodiments, e.g., relative movement of retractor arms in a linear, arcuate, ratcheting, and/or pivoting motion, the types of blades and their relative locations, among other things. Further discussion regarding an example method of use of disclosed retractor and retractor module embodiments and surgical approaches utilizing the outer dilator  94  is shown in the top down view of  FIG. 130  and the perspective view of  FIG. 131 , among other places. 
     Referring generally to  FIGS. 82-87  a modular blade  120  and an extendable blade  130  for coupling to modular blade  120  is disclosed.  FIGS. 82 and 83  are various perspective views of a modular blade  120  and  FIGS. 84 and 85  are various perspective views of an extendable blade  130  for coupling to modular blade  120 .  FIG. 86  is a front view of modular blade  120  and extendable blade  130  side by side and  FIG. 87  is a top down view of modular blade  120  and extendable blade  130 . In various embodiments, the modular blade  120  may be referred to as modular because it may couple to various extendable blades  130  such that extendable blades  130  may extend relative to modular blade  120 , e.g., blade  120  and blade  130  may be configured as a telescoping blade system. 
     Modular blade  120  may extend from a proximal end  120   p  to a distal end  120   d  in a proximal-to-distal direction (may also be referred to as longitudinal direction). The proximal end  120   p  may include an engagement feature  126  having spring loaded tabs  127  for coupling to a blade engagement mechanism in the same, similar, and/or substantially the same way as explained above. The distal end  120   d  may include a tip portion  121 . In the example embodiment, tip portion  121  comprises a substantially planar outer surface that tapers towards a centerline of modular blade  120  and terminates as a blunt chisel shaped end having a relatively smaller thickness than the remaining portions of modular blade  120 , for example. Modular blade  120  may include a pair of rails  124  that extend from proximal end  120   p  towards distal end  120   d . For example, a first rail  124  may extend along a first side of blade  120  in the proximal-to-distal direction and a second rail  124 , opposite the first rail  124 , may extend along a second side of blade  120  in the proximal-to-distal direction. In various embodiments, rails  124  may define a receiving channel for receiving extendable blade  130  as will be explained in further detail below. 
     Additionally, modular blade  120  may include an aperture  122  extending through a top surface of blade  120  at the proximal end  120   p  and penetrating through the inside surface of blade  120  at oval shaped opening  122   a , for example. In various embodiments, aperture  122  may comprise a passageway (in a cross section view) that is inclined away from the outside surface of blade  120  and towards the inside surface of blade  120  such that the passageway forms an oval shaped opening  122   a  on the inside surface of blade  120 . In cross section, the passageway of aperture  122  may resemble a circle, oval, pentagon, square, rectangle, and/or any combination thereof. Aperture  122  may provide access for light fixtures and other diagnostic tools such as endoscopes, electrodes, temperature sensors, suction devices, and etc. that may be insert therein. 
     Modular blade  120  may include a contoured channel  123  for connecting with extendable blade  130  and facilitating the forward and backward relative motion of extendable blade  130  in the proximal-to-distal direction, for example. As shown best in  FIG. 83 , contoured channel  123  may include a relatively large central arcuate channel portion  123   a  having a pair of relatively smaller arcuate channels  123   b  on opposite sides of channel portion  123   a , for example. Additionally, contoured channel  123  may include a plurality of indentations  125  extending in a proximal-to-distal direction, for example. In various embodiments, indentations  125  may be circular shaped indentations, oval shaped indentations, hexagonal shaped indentations, parallelogram shaped indentions, and/or any combination thereof. A distal end of contoured channel  123  may include a stop feature  129  for preventing extendable blade  130  from extending too far in the proximal-to-distal direction. 
     Extendable blade  130  may extend from a proximal end  130   p  to a distal end  130   d  in a proximal-to-distal direction (also referred to as a longitudinal direction). The distal end may include a tip portion  131  tapering towards a centerline of extendable blade  130  and terminating as a blunt chisel shaped end having a relatively smaller thickness than the remaining portion of extendable blade  130 , for example. In the example embodiment, an outside surface of extendable blade  130  may include an engagement feature  134  for connecting with contoured channel  123 , for example. Engagement feature  134  may include a proximal engagement rail  135  having a size and shape generally corresponding to a size and shape of contoured channel  123 . For example, proximal engagement rail  135  may have a size and shape generally corresponding to the relatively large central arcuate channel portion  123   a  and the pair of relatively smaller arcuate channels  123   b , for example. Additionally, engagement feature  134  may include a medial engagement rail  136  having a width approximately corresponding to the relatively large central arcuate channel portion  123   a  of modular blade  120 , for example. In various embodiments, an exposed surface of medial engagement rail  136  may be substantially planar although in other embodiments the exposed surface may be arcuately shaped to correspond and/or approximate the geometrical profile of contoured channel  123 , for example. 
     In various embodiments, engagement feature  134  may include at least one protrusion  133  having a size and shape generally corresponding to a size and shape of indentation  125 . For example, protrusion  133  may selectively be seated within any one of indentations  125  to secure extendable blade  130  in any one position of the plurality of positions defined by indentations  125 . In various embodiments, protrusion  133  may be a circular shaped protrusion, oval shaped protrusion, hexagonal shaped protrusion, parallelogram shaped protrusion, and/or any combination thereof. In various embodiments, protrusion  133  may extend away from extendable blade  130  in a direction perpendicular to the proximal-to-distal direction a distance that is relatively farther out than medial engagement rail  136  and/or proximal engagement rail  135 , for example. In some embodiments, protrusion  133  may be spring loaded and/or biased. In other embodiments, protrusion  133  may be a rigid non movable structure. 
     In various embodiments, engagement feature  134  may include a distal engagement rail  137  having a size and shape generally corresponding to a size and shape of contoured channel  123 . For example, distal engagement rail  137  may have a size and shape generally corresponding to the relatively large central arcuate channel portion  123   a  and the pair of relatively smaller arcuate rails  123   b , for example. Additionally, engagement feature  134  may include a stop feature  138  that may abut against stop feature  129  of modular blade  120  to prevent extendable blade  130  from disengaging with modular blade  120 , for example. For example, in a fully extended position, stop feature  138  of extendable blade may directly contact stop feature  129  of modular blade  120  and prevent extendable blade  130  from extending too far that engagement feature  134  becomes unseated from contoured channel  123 . 
     With reference to  FIG. 86 , the inside surface of modular blade  120  and the outside surface of extendable blade  130  is illustrated. In various embodiments, extendable blade  130  may operably couple to modular blade  120  by inserting engagement feature  134  into channel  123 . As explained above, extendable blade  130  may move forward and backward in a proximal-to-distal direction within contoured channel  123 . For example, extendable blade  130  may extend forward and backward within contoured channel  123  and protrusion  133  may be seated within any one of indentations  125 . For example, when modular blade  120  and extendable blade  130  are coupled together as a system, they may be referred to as a telescoping blade system. 
     With reference to  FIG. 87 , a top down view of modular blade  120  and extendable blade  130  is illustrated. In the example embodiment, it is shown that rails  124  define a cavity and/or channel for receiving extendable blade  130 . For example, extendable blade  130  has a width in a lateral direction that corresponds to a distance between rails  124  and a thickness of extendable blade  130  corresponds to a depth of the cavity and/or channel between and defined by rails  124 . In various embodiments, the outside lateral edges  1301  of extendable blade  130  may be inset within the receiving cavity defined by rails  124  such that they frictionally engage and slide across the interior side surfaces of modular blade  120 , for example. In this way, rails  124  may provide a bearing surface for retaining extendable blade  130  therein while also allowing extendable blade  130  to move forward and backward in the proximal-to-distal direction. Additionally, it is shown that engagement feature  134  has a size and shape corresponding to contoured channel  123 . For example, the curved surfaces of proximal engagement rail  135  may be inset within (mated within) contoured channel  123  and frictionally engage and slide across the interior surfaces defined by the relatively large central arcuate channel portion  123   a  and/or pair of relatively smaller arcuate channels  123   b  on opposite sides of channel portion  123   a , for example. 
     Referring generally to  FIGS. 88-93  a modular blade  320  and an extendable blade  330  for coupling to modular blade  320  is disclosed.  FIGS. 88 and 89  are various perspective views of a modular blade  320  and  FIGS. 90 and 91  are various perspective views of an extendable blade  330  for coupling to modular blade  320 .  FIG. 92  is a front view of modular blade  320  and extendable blade  330  side by side and  FIG. 93  is a top down view of modular blade  320  and extendable blade  330 . In various embodiments, modular blade  320  and extendable blade  330  may be configured as a telescoping blade system. 
     Modular blade  320  may extend from a proximal end  320   p  to a distal end  320   d  in a proximal-to-distal direction (may also be referred to as longitudinal direction). The proximal end  320   p  may include an engagement feature  326  having spring loaded tabs  327  for coupling to a blade engagement mechanism in the same, similar, and/or substantially the same way as explained above. The distal end  320   d  may include a tip portion  321 . In the example embodiment, tip portion  321  comprises a substantially planar outer surface that tapers towards a centerline of modular blade  320  and terminates as a blunt chisel shaped end having a relatively smaller thickness than the remaining portions of modular blade  320 , for example. Modular blade  320  may include a pair of rails  324   a  and  324   b  that extend from proximal end  320   p  towards distal end  320   d . For example, a first rail  324   a  may extend along a first lateral side of blade  320  in the proximal-to-distal direction and a second rail  324   b , opposite first rail  324   a , may extend along a second lateral side of blade  320  in the proximal-to-distal direction. First rail  324   a  may extend laterally away from extendable blade  320  farther than second rail  324   b , for example. For example still, second rail  324   b  may be inset towards a center of modular blade  320  relative to first rail  324   a  and  324   a  may be outset relative to second rail  324   b  (see  FIG. 93 ). First rail  324   a  may define a first receiving cavity  324   y  and second rail  324   z  may define a second receiving cavity  324   z , for example. Additionally, modular blade may include a channel  319  extending along the outside surface of modular blade  320  in the proximal-to-distal direction and/or from a proximal end to a distal end. Channel  319  may have a size and shape generally corresponding to a size and shape of channel  339  of extendable blade  330 , for example. In various embodiments, a stability pin may be positioned within channels  319  and  339 , for example. In various embodiments, rails  324   a ,  324   b , and channel  319  may define a contoured receiving channel for receiving extendable blade  330 , as will be explained in further detail below. 
     Modular blade  320  may include an aperture  322  extending through a top surface of blade  320  at the proximal end  320   p  and penetrating through the inside surface of blade  320  at oval shaped opening  322   a , for example. Aperture  322  may have the same, similar, and/or substantially the same features and functionality of aperture  122 . Accordingly, duplicative description will be omitted. Modular blade  320  may include a contoured channel  323  for connecting with extendable blade  330  and facilitating the forward and backward relative motion of extendable blade  330  in the proximal-to-distal direction, for example. Contoured channel may include a relatively large central arcuate channel portion  323   a  having a pair of relatively smaller arcuate channels  323   b  on opposite sides of channel portion  323   a , for example. Additionally, contoured channel  323  may include a plurality of indentations  325  extending in a proximal-to-distal direction, for example. In various embodiments, indentations  325  may be circular shaped indentations, oval shaped indentations, hexagonal shaped indentations, parallelogram shaped indentions, and/or any combination thereof. A distal end of contoured channel  323  may include a stop feature  329  for preventing extendable blade  330  from extending too far in the proximal-to-distal direction. 
     Extendable blade  330  may extend from a proximal end  330   p  to a distal end  330   d  in a proximal-to-distal direction (also referred to as a longitudinal direction). The distal end may include a tip portion  331  tapering towards a centerline of extendable blade  330  and terminating as a blunt chisel shaped end having a relatively smaller thickness than the remaining portion of extendable blade  330 , for example. In the example embodiment, an outside surface of extendable blade  330  may include an engagement feature  334  for connecting with contoured channel  323 , for example. Engagement feature  334  may include a proximal engagement rail  335  having a size and shape generally corresponding to a size and shape of contoured channel  323 . For example, proximal engagement rail  335  may have a size and shape generally corresponding to the relatively large central arcuate channel portion  323   a  and the pair of relatively smaller arcuate channels  323   b , for example. Additionally, engagement feature  334  may include a medial engagement rail  336  having a width approximately corresponding to the relatively large central arcuate channel portion  323   a  of modular blade  320 , for example. In various embodiments, an exposed surface of medial engagement rail  336  may be substantially planar although in other embodiments the exposed surface may be arcuately shaped to correspond and/or approximate the geometrical profile of contoured channel  323 , for example. 
     In various embodiments, engagement feature  334  may include at least one protrusion  333  having a size and shape generally corresponding to a size and shape of indentation  325 . For example, protrusion  333  may selectively be seated within any one of indentations  325  to secure extendable blade  330  in any one position of the plurality of positions defined by indentations  325 . In various embodiments, protrusion  333  may be a circular shaped protrusion, oval shaped protrusion, hexagonal shaped protrusion, parallelogram shaped protrusion, and/or any combination thereof. In various embodiments, protrusion  333  may extend away from extendable blade  330  in a direction perpendicular to the proximal-to-distal direction a distance that is relatively farther out than medial engagement rail  336  and proximal rail  335 , for example. In some embodiments, protrusion  333  may be spring loaded and/or biased. In other embodiments, protrusion  333  may be a rigid non movable structure. 
     In various embodiments, engagement feature  334  may include a distal engagement rail  337  having a size and shape generally corresponding to a size and shape of contoured channel  323 . For example, distal engagement rail  337  may have a size and shape generally corresponding to the relatively large central arcuate channel portion  323   a  and the pair of relatively smaller arcuate rails  323   b , for example. Additionally, engagement feature  334  may include a stop feature  338  that may abut against stop feature  329  of modular blade  320  to prevent extendable blade  330  from disengaging with modular blade  320  as explained above, for example. 
     With reference to  FIG. 91 , the inside surface of modular blade  320  and the outside surface of extendable blade  330  is illustrated. In various embodiments, extendable blade  330  may operably couple to modular blade  320  by inserting engagement feature  334  into channel  323 . As explained above, extendable blade  330  may move forward and backward in a proximal-to-distal direction within contoured channel  323 . For example, extendable blade  330  may extend forward and backward within contoured channel  323  and protrusion  333  may be seated within any one of indentations  325 . For example, when modular blade  320  and extendable blade  330  are coupled together as a system, they may be referred to as a telescoping blade system. 
     With reference to  FIG. 92 , a top down view of modular blade  320  and extendable blade  330  is illustrated. In the example embodiment, it is shown that rails  324   a ,  324   b  and channel  319  define a cavity and/or channel for receiving extendable blade  330 . For example, extendable blade  330  has a width in a lateral direction that corresponds to a distance between rails  324   a ,  324   b  and a thickness of extendable blade  330  corresponds to a depth of the cavity and/or channel between and defined by rails  324   a  and  324   b . In various embodiments, the outside lateral edge  3301  of extendable blade  330  may be mated within the receiving cavity  324   y  defined by rail  324   a  and an outside lateral rail  332  of extendable blade  330  may be mated within receiving cavity  324   z , for example. In various embodiments, outside lateral rail  332  of extendable blade  330  may extend along the outside lateral edge of extendable blade  330  in the proximal-to-distal direction until about the tip portion  331 , for example. Additionally, channel  319  of extendable blade  330  may be mated within channel  319  of modular blade  320 . In this way, rails  324   a  and  324   b  may provide a bearing surface for retaining extendable blade  330  therein while also allowing extendable blade  330  to move forward and backward in the proximal-to-distal direction. Additionally, it is shown that engagement feature  334  has a size and shape corresponding to contoured channel  323 . For example, the curved surfaces of proximal engagement rail  335  may be inset within contoured channel  323  and frictionally engage and slide across the interior surfaces defined by the relatively large central arcuate channel portion  323   a  and/or pair of relatively smaller arcuate channels  323   b  on opposite sides of channel portion  323   a , for example. 
     Referring generally to  FIGS. 94-99  a modular blade  420  and an extendable blade  430  for coupling to modular blade  420  is disclosed.  FIGS. 94 and 95  are various perspective views of a modular blade  420  and  FIGS. 96 and 97  are various perspective views of an extendable blade  430  for coupling to modular blade  420 .  FIG. 98  is a front view of modular blade  420  and extendable blade  430  side by side and  FIG. 99  is a top down view of modular blade  420  and extendable blade  430 . In various embodiments, modular blade  420  and extendable blade  430  may be configured as a telescoping blade system. 
     Modular blade  420  may extend from a proximal end  420   p  to a distal end  420   d  in a proximal-to-distal direction (may also be referred to as longitudinal direction). The proximal end  420   p  may include an engagement feature  426  having spring loaded tabs  427  for coupling to a blade engagement mechanism in the same, similar, and/or substantially the same way as explained above. The distal end  420   d  may include a tip portion  421 . In the example embodiment, tip portion  421  comprises a substantially planar outer surface that tapers towards a centerline of modular blade  420  and terminates as a blunt chisel shaped end having a relatively smaller thickness than the remaining portions of modular blade  420 , for example. As best seen in  FIG. 95 , in some embodiments tip portion  421  may curve inward and/or arc inward in various embodiments, for example. Modular blade  420  may include a pair of rails  424   a  and  424   b  that extend from proximal end  420   p  towards distal end  420   d . For example, a first rail  424   a  may extend along a first lateral side of blade  420  in the proximal-to-distal direction and a second rail  424   b , opposite first rail  424   a , may extend along a second lateral side of blade  420  in the proximal-to-distal direction. In various embodiments, modular blade  420  may be symmetrical on either side of a centerline extending in the proximal-to-distal direction, for example. 
     In various embodiments, first rail  424   a  may define a first receiving cavity  424   y  and second rail  424   b  may define a second receiving cavity  424   z , for example (see  FIG. 99 ). Additionally, modular blade  420  may include a first channel  419   a  and second channel  419   b  extending along the inside surface of modular blade  420  in the proximal-to-distal direction and/or from a proximal end to a distal end, for example. Channels  419   a ,  419   b  may have a size and shape generally corresponding to a size and shape of channels  439   a  and  439   b  of extendable blade  430 , for example. In various embodiments, rails  424   a ,  424   b , and channels  419   a ,  419   b  may define a contoured receiving channel for receiving extendable blade  430 , as will be explained in further detail below. 
     Modular blade  420  may include at least one aperture  422  extending through a top surface of blade  420  at the proximal end  420   p  and penetrating through the inside surface of blade  420  at oval shaped opening  422   a , for example. Apertures  422  may have the same, similar, and/or substantially the same features and functionality of aperture  122 . Accordingly, duplicative description will be omitted. Modular blade  420  may include a contoured channel  423  for connecting with extendable blade  430  and facilitating the forward and backward relative motion of extendable blade  430  in the proximal-to-distal direction, for example. Contoured channel may include a relatively large central arcuate channel portion  423   a  having a pair of relatively smaller arcuate channels  423   b  on opposite sides of channel portion  423   a , for example. Additionally, contoured channel  423  may include a plurality of indentations  425  extending in a proximal-to-distal direction, for example. In various embodiments, indentations  425  may be circular shaped indentations, oval shaped indentations, hexagonal shaped indentations, parallelogram shaped indentions, and/or any combination thereof. A distal end of contoured channel  423  may include a stop feature  429  for preventing extendable blade  430  from extending too far in the proximal-to-distal direction. 
     Extendable blade  430  may extend from a proximal end  430   p  to a distal end  430   d  in a proximal-to-distal direction (also referred to as a longitudinal direction). The distal end may include a tip portion  431  and extendable blade  430  may be generally shaped like a rectangle (in a plan view). In the example embodiment, an outside surface of extendable blade  430  may include an engagement feature  434  for connecting with contoured channel  423 , for example. Engagement feature  434  may include a proximal engagement rail  435  having a size and shape generally corresponding to a size and shape of contoured channel  423 . For example, proximal engagement rail  435  may have a size and shape generally corresponding to the relatively large central arcuate channel portion  423   a  and the pair of relatively smaller arcuate channels  423   b , for example. Additionally, engagement feature  434  may include a medial engagement rail  436  having a width approximately corresponding to the relatively large central arcuate channel portion  423   a  of modular blade  420 , for example. In various embodiments, an exposed surface of medial engagement rail  436  may be substantially planar although in other embodiments the exposed surface may be arcuately shaped to correspond and/or approximate the geometrical profile of contoured channel  423 , for example. 
     In various embodiments, engagement feature  434  may include at least one protrusion  433  having a size and shape generally corresponding to a size and shape of indentation  425 . For example, protrusion  433  may selectively be seated within any one of indentations  425  to secure extendable blade  430  in any one position of the plurality of positions defined by indentations  425 . In various embodiments, protrusion  433  may be a circular shaped protrusion, oval shaped protrusion, hexagonal shaped protrusion, parallelogram shaped protrusion, and/or any combination thereof. In various embodiments, protrusion  433  may extend away from extendable blade  430  in a direction perpendicular to the proximal-to-distal direction a distance that is relatively farther out than medial engagement rail  436  and proximal engagement rail  435 , for example. In some embodiments, protrusion  433  may be spring loaded and/or biased. In other embodiments, protrusion  433  may be a rigid non movable structure. 
     In various embodiments, engagement feature  434  may include a distal engagement rail  437  having a size and shape generally corresponding to a size and shape of contoured channel  423 . For example, distal engagement rail  437  may have a size and shape generally corresponding to the relatively large central arcuate channel portion  423   a  and the pair of relatively smaller arcuate channels  423   b , for example. Additionally, engagement feature  434  may include a stop feature  438  that may abut against stop feature  429  of modular blade  420  to prevent extendable blade  430  from disengaging with modular blade  420  as explained above, for example. 
     With reference to  FIG. 98 , the inside surface of modular blade  420  and the outside surface of extendable blade  430  is illustrated. In various embodiments, extendable blade  430  may operably couple to modular blade  420  by inserting engagement feature  434  into channel  423 . As explained above, extendable blade  430  may move forward and backward in a proximal-to-distal direction within contoured channel  423 . For example, extendable blade  430  may extend forward and backward within contoured channel  423  and protrusion  433  may be seated within any one of indentations  425 . 
     With reference to  FIG. 99 , a top down view of modular blade  420  and extendable blade  430  is illustrated. In the example embodiment, it is shown that rails  424   a ,  424   b  and channels  419   a ,  419   b  define a cavity and/or channel for receiving extendable blade  430 . For example, extendable blade  430  has a width in a lateral direction that corresponds to a distance between rails  424   a ,  424   b  and a thickness of extendable blade  430  corresponds to a depth of the cavity and/or channel between and defined by rails  424   a  and  424   b . In various embodiments, the outside lateral rail  432   a  of extendable blade  430  may be mated within the receiving cavity  424   y  defined by rail  424   a  and an outside lateral rail  432   b  of extendable blade  430  may be mated within receiving cavity  424   z , for example. In various embodiments, outside lateral rail  432   a ,  432   b  of extendable blade  430  may extend along the outside lateral edge of extendable blade  430  in the proximal-to-distal direction until about the tip portion  431 , for example. Additionally, channels  439   a ,  439   b  of extendable blade  430  may be mated within channels  419   a ,  419   b  of modular blade  420 . In this way, rails  424   a  and  424   b  may provide a bearing surface for retaining extendable blade  430  therein while also allowing extendable blade  430  to move forward and backward in the proximal-to-distal direction. Additionally, it is shown that engagement feature  434  has a size and shape corresponding to contoured channel  423 . For example, the curved surfaces of proximal engagement rail  435  may be inset within contoured channel  423  and frictionally engage and slide across the interior surfaces defined by the relatively large central arcuate channel portion  423   a  and/or pair of relatively smaller arcuate channels  423   b  on opposite sides of channel portion  423   a , for example. 
     Referring generally to  FIGS. 100-105  a modular blade  440  and various extendable blades  450   a ,  450   b , and  450   c  for coupling to modular blade  440  is disclosed.  FIGS. 100-101  are various perspective views of a modular blade  440  and  FIGS. 102-104  are various perspective views of extendable blades  450   a ,  450   b , and  450   c  for coupling to modular blade  440 .  FIG. 105  is a front view of extendable blades  450   a ,  450   b , and  450   c . In various embodiments, modular blade  440  and extendable blades  450   a ,  450   b , and  450   c  may be configured as a telescoping blade system. In various embodiments, the extendable blades  450   a ,  450   b , and  450   c  may have a relatively long and narrow tip section that may be advantageous for distracting soft tissues of a patient, for example. 
     Modular blade  440  may extend from a proximal end  440   p  to a distal end  440   d  in a proximal-to-distal direction (may also be referred to as longitudinal direction). The proximal end  440   p  may include an engagement feature  446  having spring loaded tabs  447  for coupling to a blade engagement mechanism in the same, similar, and/or substantially the same way as explained above. The distal end  440   d  may include a tip portion  441 . In the example embodiment, tip portion  441  comprises a substantially planar outer surface that tapers towards a centerline of modular blade  440  and terminates as a blunt chisel shaped end having a relatively smaller thickness than the remaining portions of modular blade  440 , for example. Modular blade  440  may include a pair of rails  444  that extend from proximal end  440   p  towards distal end  440   d . For example, a first rail  444  may extend along a first side of blade  440  in the proximal-to-distal direction and a second rail  444 , opposite the first rail  444 , may extend along a second side of blade  440  in the proximal-to-distal direction. In various embodiments, rails  444  may define a receiving channel for receiving any one of extendable blades  450   a ,  450   b , and  450   c , for example. 
     Modular blade  440  may include a contoured channel  443  for connecting with extendable blades  450   a ,  450   b , and  450   c  and facilitating the forward and backward relative motion of extendable blades  450   a ,  450   b , and  450   c  in the proximal-to-distal direction, for example. As shown best in  FIG. 83 , contoured channel  443  may include a relatively large central arcuate channel portion  443   a  having a pair of relatively smaller arcuate channels  443   b  on opposite sides of channel portion  443   a , for example. Additionally, contoured channel  443  may include a plurality of indentations  445  extending in a proximal-to-distal direction, for example. In various embodiments, indentations  445  may be circular shaped indentations, oval shaped indentations, hexagonal shaped indentations, parallelogram shaped indentions, and/or any combination thereof. A distal end of contoured channel  443  may include a stop feature  449  for preventing extendable blades  450   a ,  450   b , and  450   c  from extending too far in the proximal-to-distal direction. 
     Extendable blades  450   a ,  450   b , and  450   c  may extend from a proximal end  450   p  to a distal end  450   d  in a proximal-to-distal direction (also referred to as a longitudinal direction). The distal end may include a relatively long tip portion  451  that tapers near a medial portion of extendable blades  450   a ,  450   b , and  450   c  and then extends towards distal end  450   d  at the same, similar, and/or substantially the same width. Relatively long tip portion  451  may terminate as an arcuate curved end with chamfered surfaces, for example. As seen best in  FIG. 105 , extendable blades  450   a ,  450   b , and  450   c  are similar and have differently sized tip portions  451 . For example, extendable blade  450   a  has a relatively wider tip portion  451  than extendable blades  450   b  and  450   c , for example. Extendable blade  450   b  has a relatively narrower tip portion  451  than extendable blade  450   a  and a relatively wider tip portion  451  than extendable blade  450   c , for example. Extendable blade  450   c  has a relatively narrow tip portion  451  than extendable blades  450   a  and  450   b , for example. The other remaining features and components may be the same, substantially the same, and or similar. 
     In the example embodiment, an outside surface of extendable blades  450   a ,  450   b , and  450   c  may include an engagement feature  454  for connecting with contoured channel  443 , for example. Engagement feature  454  may include a proximal engagement rail  455  having a size and shape generally corresponding to a size and shape of contoured channel  443 . For example, proximal engagement rail  455  may have a size and shape generally corresponding to the relatively large central arcuate channel portion  443   a  and the pair of relatively smaller arcuate channels  443   b , for example. Additionally, engagement feature  454  may include a medial engagement rail  456  having a width approximately corresponding to the relatively large central arcuate channel portion  443   a  of modular blade  440 , for example. In various embodiments, an exposed surface of medial engagement rail  456  may be substantially planar although in other embodiments the exposed surface may be arcuately shaped to correspond and/or approximate the geometrical profile of contoured channel  443 , for example. 
     In various embodiments, engagement feature  454  may include at least one protrusion  453  having a size and shape generally corresponding to a size and shape of indentation  445 . For example, protrusion  453  may selectively be seated within any one of indentations  445  to secure extendable blades  450   a ,  450   b , and  450   c  in any one position of the plurality of positions defined by indentations  445 . In various embodiments, protrusion  453  may be a circular shaped protrusion, oval shaped protrusion, hexagonal shaped protrusion, parallelogram shaped protrusion, and/or any combination thereof. In various embodiments, protrusion  453  may extend away from extendable blades  450   a ,  450   b , and  450   c  in a direction perpendicular to the proximal-to-distal direction a distance that is relatively farther out than medial engagement rail  456  and/or proximal engagement rail  455 , for example. In some embodiments, protrusion  453  may be spring loaded and/or biased. In other embodiments, protrusion  453  may be a rigid non movable structure. 
     In various embodiments, engagement feature  454  may include a distal engagement rail  457  having a size and shape generally corresponding to a size and shape of contoured channel  443 . For example, distal engagement rail  457  may have a size and shape generally corresponding to the relatively large central arcuate channel portion  443   a  and the pair of relatively smaller arcuate channels  443   b , for example. Additionally, engagement feature  454  may include a stop feature  458  that may abut against stop feature  449  of modular blade  440  to prevent extendable blades  450   a ,  450   b , and  450   c  from disengaging with modular blade  440 , for example. For example, in a fully extended position, stop feature  449  of extendable blade may directly contact stop feature  458  of extendable blades  450   a ,  450   b , and  450   c  and prevent extendable blades  450   a ,  450   b , and  450   c  from extending too far that engagement feature  454  becomes unseated from contoured channel  443 . 
     In various embodiments, extendable blades  450   a ,  450   b , and  450   c  may operably couple to modular blade  440  by inserting engagement feature  454  into channel  443 . As explained above, extendable blades  450   a ,  450   b , and  450   c  may move forward and backward in a proximal-to-distal direction within contoured channel  443 . For example, extendable blades  450   a ,  450   b , and  450   c  may extend forward and backward within contoured channel  443  and protrusion  453  may be seated within any one of indentations  445 . For example, when modular blade  440  and any one of extendable blades  450   a ,  450   b , and  450   c  are coupled together as a system, they may be referred to as a telescoping blade system and such system may be particularly advantageous for distracting and retracting various soft patient tissue, for example. 
     In the example embodiment, rails  444  may define a cavity and/or channel for receiving any one of extendable blades  450   a ,  450   b , and  450   c . For example, extendable blades  450   a ,  450   b , and  450   c  may have a width in a lateral direction that corresponds to a distance between rails  444  and a thickness of each extendable blades  450   a ,  450   b , and  450   c  may correspond to a depth of the cavity and/or channel between and defined by rails  444 , for example. In various embodiments, any one corresponding pair of outside lateral edges of extendable blades  450   a ,  450   b , and  450   c  may be inset within the receiving cavity defined by rails  444  such that a pair of lateral edges frictionally engages and slides across the interior side surfaces of modular blade  440 , for example. In this way, rails  444  may provide a bearing surface for retaining any one of extendable blades  450   a ,  450   b , and  450   c  therein while also allowing any inserted blade to move forward and backward in the proximal-to-distal direction. Additionally, in various embodiments engagement feature  454  has a size and shape corresponding to contoured channel  443 . For example, the curved surfaces of proximal engagement rail  455  may be inset within (mated within) contoured channel  443  and frictionally engage and slide across the interior surfaces defined by the relatively large central arcuate channel portion  443   a  and/or pair of relatively smaller arcuate channels  443   b  on opposite sides of channel portion  443   a , for example. 
     Additional Retractor Embodiments 
     Referring generally to  FIGS. 106-108D  a modular blade  140  and an extendable blade  150  having a pointed end  151  is disclosed. In some embodiments, extendable blade  150  may be referring to as an “impact blade” on account of being configured with a pointed end  151  that may be driven into a disc space, for example.  FIG. 106  is a front view of the modular blade  140  and extendable blade  150  slidably coupled together and  FIG. 107  is a rear view of the modular blade  140  and extendable blade  150  slidably coupled together.  FIGS. 108A and 108B  are various exploded parts views of the modular blade  140  and extendable blade  150 .  FIG. 108C  is a perspective view of the modular blade  140  and  FIG. 108D  is a top down view of the modular blade  140 . 
     In the example embodiment, modular blade  140  may include an engagement feature  146  having similar functional attributes to blade engagement feature  126  explained above with respect to blade  120 . However, in this embodiment, the engagement feature  146  of modular blade  140  does not include spring loaded tabs  127 , for example. Rather, as best seen in  FIGS. 108B, 108C, and 108D , engagement feature  146  comprises a raised rail  146 B having an arcuately shaped and/or curved shaped uppermost surface  146 A, for example. The raised rail portion  146 B may be offset from the outside surface of modular blade  140  by platform  146 D. In the example embodiment, a thickness or dimension of platform  146 D in a lateral direction is less than a thickness or dimension of raised rail  146 B in the lateral direction. In the example embodiment, channel portions  146 C are formed on opposite sides of platform  146 D and are located between the outside surface of modular blade  140  and the adjacent inside surface of raised rail  146 B, for example. In this way, engagement feature  146  may be configured to slidably connect to a corresponding blade coupling portion of an arm of the variously disclosed blade coupling portions having corresponding male/female features. In at least one embodiment, modular blade  140  may be securely coupled to blade coupling portion  535  shown in  FIGS. 119-121B  by sliding the modular blade  140  from beneath blade coupling portion  535  upwards into blade coupling portion  535 . For example, modular blade  140  may be configured for bottom loading as will be explained in further detail below. Additionally, any blade disclosed herein may be configured with the same, similar, or substantially the same type of engagement feature  146 . However, consistent with the disclosure herein, modular blade and engagement feature  146  may also be reversed for top loading. 
     As seen best in  FIGS. 108B, 108C, and 108D , modular blade  140  may comprise a pair of channels  143  extending along the interior surface thereof from a proximal end  140 P to a distal end  140 D. In various embodiments, the interior surface of modular blade  140  may be a curved surface  148 . Additionally, the extendable blade  150  may comprise a pair of outdented rail portions  153  extending along the side surfaces thereof from a proximal end  150 P to a distal end  150 D thereof. In the example embodiment, the blade surface of extendable blade  150  has a curved sidewall surface  158  having a size and shape generally corresponding to the interior curved surface  148  of modular blade  140 , for example. In use, the extendable blade  150  may be configured to couple to the modular blade  140  by sliding the outdented rails  153  into the interior channels  143  of modular blade  140 , for example. In this way, extendable blade  150  may be configured to slidably couple to modular blade  140  in an operable way, for example. However, it shall be understood that other embodiments may rely on a single rail  153  and a single channel  143  and that channels  143  and rails  153  may take various shapes, for example oblong, square, trapezoidal, dovetail, tongue and groove, etc. 
       FIG. 108E  is a perspective view of a driver  149  for use with the modular blade  140  and extendable blade  150 , for example. In some embodiments, driver  149  may be a referred to as an impact driver on account of being suitable for sustaining an impact force to drive extendable blade  150  forward, for example. In the example embodiment, driver  149  may extend in a longitudinal direction from a proximal end to a distal end. For example, driver  149  may include a proximal end comprising a striking end or surface  149 A having a relatively flat or smooth top surface and a circumferential side surface  149 B having various texturing. In the example embodiment, the texturing of side surface  149 B extends in a proximal to distal direction along the outside side surface of the proximal end of driver  149  as raised rails and indented valleys therebetween. The texturing may assist a surgeon in rotating driver  149  within channel  143  and in some embodiments, rotating driver  149  may be used to rotate a threaded pin (not illustrated). In some embodiments, the contouring and/or texturing may correspond to a torx head or a similar driver end, for example. In various embodiments, a shaft  149 C may couple to or be integrally formed together with the proximal end and distal end, for example. In the example embodiment, shaft  149 C may have a diameter substantially corresponding in size and shape to a diameter of channel  143 , for example. Additionally, a distal end of shaft  149 C may comprise a blunt distal end  149 D. In operation, the blunt end  149 D may contact the proximal end of extendable blade  150  for pushing extendable blade  150  forward. Additionally, a first and second driver  149  may be used together to push extendable blade  150  forward within both of channels  143 , for example. 
       FIG. 109  is a perspective view of a rectangular shaped dilator  160 . In the example embodiment, dilator  160  extends in a longitudinal direction from a proximal end  160 P to a distal end  160 D. The proximal end  160 P may include a pair of opposing curvilinear indents  165  for gripping dilator  160 , for example. In various embodiments, dilator  160  may comprise an aperture  163  or opening extending from proximal end  160 P to distal end  160 D through dilator  160 , for example. In various embodiments, dilator  160  may have planar side surfaces  161  extending in a proximal-to-distal direction. In the example embodiment, dilator  160  may further include a chiseled end or inclined end defining the distal end  160 D surfaces. For example, planar side surfaces  161  may terminate into inclined surfaces  162  which may facilitate insertion of dilator  160  into an operative corridor for example. In the example embodiment, dilator  160  is rectangular shaped and in other embodiments dilator  160  may be square shaped. Dilator  160  may be used with any type of blade disclosed herein. Dilator  160  may be particularly advantageous for use with a relatively flat planar blade such as blade  130  shown in  FIG. 84  and/or the footed tip blades disclosed below. At least one surgical configuration may comprise the utilization of a four-blade configuration comprising four substantially planar blades that generally surround the rectangular shaped dilator  160 , for example. 
     Referring generally to  FIGS. 110-114  various example shims  170 ,  180  are disclosed.  FIG. 110  is a bottom perspective view of a pair of shims  170  for coupling to various blades disclosed herein.  FIG. 111  is a perspective view of a relatively short shim  170  having a pointed pin  173  at a distal end thereof and  FIG. 112  is a perspective view of a relatively tall shim  170  having a pointed pin  173  at a distal end thereof.  FIG. 113  is a perspective view of a relatively tall shim  170  having a blunted distal end.  FIG. 114  is a perspective view of a double-sided shim  180  for coupling to various blades disclosed herein. In the example embodiments, shim  170  may extend in a longitudinal direction from a proximal end  170 P to a distal end  170 D. The proximal end may include a tab  172  for gripping shim  170  and pushing shim  170  downward or pulling shim  170  upward, for example. As seen best in  FIG. 110 , shim  170  may comprise an arcuate rail  171  having a size and shape generally corresponding to a channel of a blade, for example channel  143  of modular blade  140 . Additionally, in various embodiments, tab  172  may comprise a relatively smooth planar upper surface that is strong enough to sustain an impact for driving or tapping of shim  170 . For example, a surgeon may provide an impact force to tab  172  by a mallet or hammer which drives shim  170  forward while remaining partially constrained within a corresponding channel of a blade. In striking tab  172 , the shim  170  may be thrust forward or in a distal direction thereby inserting pin  173  into patient anatomy such as a bone or disc space, for example. Each shim  170  may have various dimensioned side surfaces for abutting against patient tissue. As seen in  FIG. 111 , some shim  170  embodiments may include a working surface  175  extending for a relatively short distance in the longitudinal direction and for a relatively great distance in a lateral direction substantially perpendicular to the longitudinal direction of shim  170 , for example. As seen in the example embodiment of  FIG. 112 , some shim  170  embodiments may include a working surface  176  extending for a relatively long distance in a longitudinal direction and for a relatively short distance in a lateral direction substantially perpendicular to the longitudinal direction of shim  170 , for example. In the example embodiment of  FIG. 112 , working surface  176  extends in the longitudinal direction for slightly less than half the length of the shim  170  in the longitudinal direction. As seen in the example embodiment of  FIG. 113 , some shim  170  embodiments may include a working surface  177  extending for a relatively long distance in a longitudinal direction and for a relatively short distance in a lateral direction substantially perpendicular to the longitudinal direction of shim  170 , for example. In the example embodiment of  FIG. 113 , working surface  177  extends in the longitudinal direction for more than half the length of the shim  170  in the longitudinal direction. 
       FIG. 114  is an example embodiment of a double-sided shim  180 . In this embodiment, shim  180  includes a pair of tabs  182 , and a pair of rails  181 . In this way, shim  180  may slidably couple to a pair of corresponding channels of a blade, for example channels  143  of modular blade  140 . In the example embodiment of  FIG. 114 , shim  180  comprises a first working surface  184  extending away from shim  180  in a first lateral direction perpendicular to the longitudinal direction and a second working surface  185  extending away from shim  180  in a second lateral direction perpendicular to the longitudinal direction. In this embodiment, working surfaces  184 ,  185  are disposed on opposite sides of a centerline  189  of shim  180 . 
     Referring generally to  FIGS. 115A-116B  a blade adjustment and positioning tool  250  is disclosed.  FIG. 115A  is a perspective view of a blade adjustment and positioning tool  250  and  FIG. 115B  is an exploded parts view of the blade adjustment and positioning tool  250 .  FIG. 116A  is an outside surface perspective view of the blade adjustment and positioning tool engaged with a modular blade and an extendable blade and  FIG. 116B  is an inside surface perspective view of the blade adjustment and positioning tool engaged with a modular blade and an extendable blade, for example. In the example embodiment, tool  250  may extend in a longitudinal direction from a proximal end  250 P to a longitudinal end  250 D, for example. In the example embodiment, the proximal end may be defined by a rotatable turnkey  251  and the distal end may be defined by a tab  256 . 
     In the example embodiment, the first portion  250 A may comprise a gripping portion  255  having a plurality of gripping indentations extending along a length thereof, for example. Additionally, the gripping portion may include a centrally disposed shaft extending therethrough in the longitudinal direction between proximal aperture  257 A and medial aperture  257 B, for example. Additionally, the second portion may include a matting rail  258  having a size and shape that corresponds to a size and shape of a channel of modular blade  120 , for example channel  123  shown in  FIG. 83 . However, it shall be understood that reference to channel  123  is by example only, and that matting rail  258  and the corresponding channel of modular blade  120  does not necessarily need indentations  125  and arcuate channel portions  123 B, for example. In various embodiments, the distal end of first portion  250 A may be defined by tab  256 . In the example embodiment, tab  256  is offset laterally from an extension axis extending through proximal aperture  257 A and medial aperture  257 B, for example. 
     Second portion  250 B may include a turnkey  251  and/or a knob at a proximal end thereof. Turnkey  251  may be coupled to or monolithically formed with primary shaft  252  and extension shaft  253 . In various embodiments, extension shaft  243  may comprise a drive feature or driving head  254  at a distal end thereof. In operation, second portion  250 B may be insert inside of first portion  250 A by inserting the driving head  254 , extension shaft  253 , and primary shaft  252  through proximal aperture  257 A. Due to the particular design of this embodiment, the primary shaft  252  may be rotatably disposed within the central shaft of the first portion and primary shaft  252  may have a size and shape generally corresponding to a size and shape of the central shaft of the first portion, e.g., substantially the same diameter and a length substantially the same as a distance between proximal aperture  257 A and medial aperture  257 B. Extension shaft  253  may be partially mated to and/or disposed within an open channel  258 C of matting rail  258  such that it may freely rotate and so can driving end  254 . 
     With reference to  FIGS. 116A and 116B , tool  250  may couple to a modular blade  120  by inserting matting rail  258  with channel  123 . Additionally, as seen best in  FIG. 116B , due to the offset nature of tab  256  an inside surface of tab  256  may be directly adjacent to and/or directly contact an inside surface of extendable blade  130 . In this way, tool  250  may provide a fulcrum or handle to manipulate the modular blade  120  and extendable blade  130 . At least one particularly advantageous use of tool  250  may be when modular blade  120  and extendable blade  130  are coupled to a free hand module, as explained above, which may not have actuators to cause pivoting and/or angulation, e.g., free hand module  900  as shown in  FIG. 49B . Additionally, in some embodiments, an end user may initially mate first portion  250 A to modular blade  120  and extendable blade  130 , then insert second portion into first portion, and slide second portion forward in a distal direction such that it pushes extendable blade  130  forward. In some embodiments, a chiseled end of second portion, e.g., drive feature  254 , may unseat a protrusion of extendable blade  130  from a corresponding indentation of modular blade  120 , e.g., protrusion  133  and indentations  125  (see  FIGS. 83-84 ). In this way, an end user may utilize tool  250  to extend a position of extendable blade  130  via second portion  250 B and may use tool  250  as a fulcrum or handle for applying a mechanical advantage as a fulcrum to modular blade  250  and extendable blade  230 , for example. Additionally, in at least some embodiments, because drive end  254  may be rotatable, it may facilitate the unseating of the protrusion of the extendable blade  130  from the corresponding indentation of modular blade  120 . 
     Referring generally to  FIGS. 117A-118E , various views of a modular blade  260  and an extendable blade  262  having a footed tip  263 , a quick connect handle  270 , and a retractor mount coupler  280  are disclosed.  FIG. 117A  is a perspective view of the inside surfaces of the modular blade  260  and extendable blade  262  and  FIG. 117B  is a perspective view of the outside surfaces of the modular blade  260  and extendable blade  262 . In the example embodiment, the extendable blade  262  has a footed tip  263  and is slidably coupled to the modular blade  260  similarly as explained above. Accordingly, duplicative description is omitted or only briefly described again. In this embodiment, modular blade  260  comprises an attachment rail  264  on the outside surface thereof adjacent the proximal end. Attachment rail  264  may include various surface texturing on the outside surface thereof, e.g., rail like peaks and channel like valleys therebetween extending in a proximal to distal direction around the outside curved surface of attachment rail  264 . In at least some embodiments, attachment rail  264  is integrally formed with modular blade  260  and in others it may be removably coupled thereto. In various embodiments, attachment rail  264  may include attachment shaft  265  extending from the proximal end of modular blade  260 , for example. The proximal most portion of attachment shaft  265  may comprise a generally cylindrical extension shaft having a planar indent  267 , a necked down portion  268 , and an end  266  that is wider than the necked down portion  268 , for example. In various embodiments, the attachment shaft  265  may quickly couple to and uncouple from a quick connect handle  270 , for example. 
       FIG. 118A  is a perspective view of a quick connect handle  270  and  FIG. 118B  is an exploded parts view of the quick connect handle  270 . In the example embodiment, quick connect handle  270  extends in a longitudinal direction from a proximal end  270 P to a distal end  270 D. The distal end  270 D may comprise a coupling aperture  269  for connecting to an attachment shaft  265  of a modular blade  260  when attachment shaft  265  is inserted therein, for example. Quick connect handle  270  may include a main body portion  275  or handle and the distal end  270 D may comprise a coupling mechanism having various mating features comprising a size and shape generally corresponding to a size and shape attachment shaft  265 , for example. In the example embodiment, the pin  272  and mating features  274  are actuated by actuator  271 . Quick connect handle  270  may couple to modular blade  260  by depressing actuator  271  and sliding attachment shaft  265  into aperture  269  such that sliding barrel  276  lockingly engages attachment shaft  265 , for example. In various embodiments, barrel  276  may be biased towards the proximal end  270 D by set pins  279  and springs  278 . In various embodiments, upon activation of actuator  271 , e.g., by depressing actuator  271  button, barrel  276  may linearly translate forward to securely couple to modular blade  260 . 
       FIG. 118C  is a perspective view of a retractor mount coupler  280 . Retractor mount coupler  280  may have many of the same, similar, and/or substantially the same components and functionality as free hand module  900  of  FIGS. 47B and 48A , for example. Accordingly, duplicative description will be omitted and/or only briefly described. In this embodiment, retractor mount coupler  280  may include a pair of gripping arms  916  for gripping on to the outside textured surface of rail  264 , for example. Additionally, retractor mount coupler  280  may include a lever  911  and a body  913  having an aperture  913 A. Lever  911  may function in the same or substantially the same way as previously explained with respect to free hand module  900 . As seen best in  FIG. 129 , retractor mount coupler  280  may couple and couple to a rod, pole, table mount extension, and/or lateral arm  1201  of a secondary module  1200 , for example.  FIG. 118D  is a perspective view of the modular blade  260  and extendable blade  262  of  FIGS. 117A-117B  coupled to the quick connect handle  270  of  FIGS. 118A-118B  and the retractor mount coupler  280  of  FIG. 118C .  FIG. 118E  is a perspective view showing the quick connect handle  270  uncoupled from the attachment shaft  265  of modular blade 
     Referring generally to  FIGS. 119-122  an additional embodiment of a modular retractor  530  is disclosed. Modular retractor  530  may have the same, similar, and or substantially the same components and functionality as explained above with respect to modular retractor  500  and modular retractor  530  may be used with any of the various add on retractor modules  600 ,  700 ,  800 ,  900 ,  1000 , and  1100  that are disclosed herein and shown in the various views of  FIGS. 20-81 , for example. Accordingly, significant duplicative description will be omitted although some aspects will be repeated for ease of explanation.  FIGS. 119 and 120  are various perspective views of modular retractor  530 .  FIG. 121A  is a top down view of modular retractor  530  and  FIG. 121B  is a bottom perspective view of a blade attachment mechanism  535 .  FIG. 122A  is an enlarged view of the embodiment of  FIGS. 119-121  with the top cover removed for ease of understanding of the internal gear system.  FIG. 122B  is an enlarged view of the embodiment of  FIGS. 119-121  from a bottom perspective showing various structural features of a table mount quick release coupler  533 . 
     In the example embodiment, modular retractor  530  may include handles  501   a ,  501   b  and arms  505  and  507 . The handles and/or actuator  502  may serve to open the retractor  530  by spreading the arms  505 ,  507  apart from one another as explained previously. Modular retractor  530  may differ from retractor  500  in a few ways. For example, the blade attachment mechanism  535  may be configured for bottom loading rather than top loading, the blade release actuator  537  may be disposed on a side surface of blade attachment mechanism  535  rather than a top surface, a release mechanism  531  may be relied upon rather than pawl  504 , and a table mount quick release connection  533  may be provided rather than table mount arm  506 , for example. 
     As seen best in  FIGS. 120 and 121B , blade attachment mechanism  535  may be configured for bottom loading of various blade engagement features, for example blade engagement feature  146  shown in  FIGS. 108B, 108C, and 108D . Generally, blade attachment mechanism  535  may have a size and shape generally corresponding to a size and shape of a corresponding blade engagement feature  146 . In the example embodiment, blade attachment mechanism  535  includes a channel  535 B that is open to the bottom and closed at the top by a curved top surface  535 A, for example. The curved top surface may have a curvature generally corresponding to a curvature of the curved uppermost surface  146 A and the channel  535 B may have a width, length, and height generally corresponding to a width, length, and height of raised rail portion  146 B, for example. In some embodiments, the curved top surface  535 A may be referred to as a stop surface and/or stopping wall. In various embodiments, channel  535 B may be flanked by supports  535 C, for example. In use, when blade engagement feature  146  is securely coupled to blade attachment mechanism  535  the side surfaces of platform  146 D may contact the side surfaces  535 D of supports  535 C such that the channel portions  146 C are mated with supports  535 C, for example. Additionally, in various embodiments the side surfaces  535 D may be chamfered and/or inclined, for example as seen best in  FIG. 121B . This arrangement may facilitate insertion of a blade thereon, for example. Furthermore, in various embodiments an outside surface of a corresponding blade and/or platform  146 D may contact the outermost surface of supports  535 C. Further still, blade release mechanism  537  may securely couple and uncouple a blade to blade attachment mechanism  535  when actuated by moving a spherical detent  537 A in and out of a corresponding aperture of a blade. 
     As seen best in  FIG. 122A , modular retractor  530  may include a distraction mechanism  50 . In this embodiment, spur gear  54  includes a plurality of teeth on a side surface thereof but may not include a plurality of teeth on a top surface thereof like the example modular retractor  500  embodiment. Additionally, a release mechanism  531  may include a tooth  531 A or tip at an end thereof having a size and shape generally corresponding to a valley between adjacent teeth of spur gear  54 . Release mechanism  531  may be biased by a spring tab or leaf spring  531 B which naturally urges tooth  531 A into a meshed arrangement with the teeth of spur gear  54  such that the spur gear  54  is prevented from rotating in a direction which would cause the arms of modular retractor  530  to collapse or close. Additionally, because release mechanism  531  may pivot in and out of a meshed arrangement with spur gear  54  an end user may cause expansion or distraction between arms  505 ,  507  of modular retractor  530  without needing to actuate release mechanism  531 . In this way, release mechanism  531  functions similarly to a pawl preventing the collapse of arms  505 ,  507  while simultaneously allowing, for example, an uninhibited expansion of arms  505 ,  507 . 
     As also seen best in  FIGS. 122A and 122B , modular retractor  530  may include a quick connect table mount  533 . Quick connect table mount  533  may include an aperture  533 Z and a tightening knob  534 . Aperture  533 Z may have a size and shape corresponding to a square or polygonal driver, for example a drive end of a wrench such as the egg wrench  10  illustrated in  FIG. 23 . As seen best in  FIG. 121A , quick connect table mount  533  may be generally disposed in a central position of the main retractor body and when viewed in a plan view may be aligned along a longitudinal axis bisecting the retractor body. This arrangement may facilitate a symmetrical load distribution, for example. However, it shall be understood that quick connect table mount  533  may be alternately disposed, for example on a side surface on the left side, medial or central area, and/or right side of the retractor body (with respect to plan view of  FIG. 121A ). Additionally, a plurality of quick connect table mounts  533  may be disposed in any viable region of modular retractor  530  and the various add on modules disclosed herein. As seen best in  FIG. 122B , quick connect table mount  533  may be configured to receive a corresponding post  363  and/or rail  362  of a quick connect arm  360  (see  FIGS. 124-125 ). In the example embodiment, quick connect table mount  533  may include a centrally disposed mating aperture  533 C accessible from a bottom side of modular retractor  530 , for example. In some embodiments, mating aperture  533 C is coaxially aligned with aperture  533 Z although this is not a requirement. In various embodiments, mating aperture  533 C may include a circumferential ring surface having a relatively greater diameter than the central portion of aperture  533 C to facilitate seating of post  363  (see  FIGS. 124-125 ) in an arrangement similar to concentric circles of varying depths. Additionally, various counter torque mating features may be disposed around and/or surround aperture  533 C, for example. In the example embodiment, a first groove  533 A extends in a direction that is substantially parallel with the longitudinal axis of modular retractor  530  and a second groove  533 B extends in a direction that is substantially perpendicular with the longitudinal axis of modular retractor  530 , e.g. second groove  533 B extends in a lateral direction with respect to modular retractor  530 . In the example embodiment, the first and second grooves  533 A,  533 B may resemble a cross shape and/or an X shape. Additionally, the ends of grooves  533 A,  533 B may be open or closed, for example one side of groove  533 B is closed and has an arcuate end surface which ensures proper alignment quick connect arm  360 , for example. In various embodiments, the rail  363  of quick connect arm  360  may nest within at least one of grooves  533 A,  533 B. Accordingly, in this embodiment an orientation of quick connect arm  360  is adjustable between a direct head on orientation type and a side or lateral orientation type, for example. At least one advantage of this configuration may be providing flexibility in orientation to a surgeon depending on different types of procedures being performed and or changes in orientation mid-procedure. 
       FIG. 123  is a perspective view of a table mount system  340  adapted for use with various retractor components disclosed herein. For example, various armatures of a quick connect table mount system may be used for supporting and manipulating various retractor embodiments disclosed herein. In the example embodiment, table mount system  340  may include a first armature  340 A and a second armature  340 B. The first armature  340 A may be slidably connected to the second armature  340 B by armature connection mechanism  345 . In at least one embodiment, second armature  340 B may include a table mount channel  349  and a table mount clamp  350 . In use the second armature  340 B may be rigidly and removably secured to an operating table by tightening clamp  350  such that table mount channel  349  is tightened to the table and arm  348  extends in a vertical direction with respect to a horizontal surface or plane of a table (not illustrated). Thereafter, the first armature  340 A may be coupled to arm  348  by positioning arm  348  within the aperture of armature connection mechanism  345  and tightening turnkey  346  such that a movable platform  345 B clamps down on to armature  348  by closing and/or reducing the size of the aperture, for example. In the example embodiment, movable platform  345 B has a channel for seating the curved surfaces of arm  348  and in some embodiments may have grooving or other texturing to facilitate a relatively strong connection. 
     First armature portion  340 A may include a first arm  341 A and a second arm  341 B that are hingedly connected together by hinge mechanism  342 , for example. In various embodiments, hinge mechanism  342  may allow for a full 360 degree rotation, or a subset thereof. At least one embodiment may include corresponding teeth that may mesh together when tightened or clamped together by a tightening knob  342 A that urges the corresponding teeth into corresponding valleys, for example. In various embodiments, second arm  341 B may be movably coupled to armature connection mechanism  345  by a ball and socket joint  343 , for example. Additionally, first armature  341  may be coupled to a snap on connector  347  by a ball and socket joint  343 , for example. Consistent with the disclosure herein, it shall be understood that any connection between the various armatures of disclosed table mount systems may be a rotatable hinge like connection, a sliding connection, and/or a ball and joint connection. Additionally, these connection types may be readily swapped and our substituted. For example, post  351  may be inset within a hollow interior of any armature end to change the connection type and/or functionality depending solely on the particular needs of an end user. 
       FIG. 124  is a first perspective view of a quick connect coupler  360  for connecting various retractor embodiments to various quick connect table mount systems disclosed herein.  FIG. 125  is a side view of the quick connect coupler  360 . Quick connect coupler  360  may include an arm  361  supporting a post  363  and rail  362  on a first end thereof. In various embodiments, the arm  361  may follow a diagonal, straight, and/or curved profile, for example. On an opposite end, quick connect coupler  360  may include an armature coupler  365 , for example. Armature coupler  365  may include a post having an inclined, chamfered, and/or dimpled end  366 , for example. Additionally, armature coupler  365  may include a grooved portion  367  to facilitate a rigid and secure engagement with a quick connect coupler of a table mount system, for example connector  347  shown in  FIG. 123 . Furthermore, a base portion of quick connect coupler  360  may include a counter torque surface  368  for resisting a rotation of quick connect coupler  360 , for example surface  368  may directly contact a corresponding counter torque surface  347 B of connector  347  (see  FIG. 123 ). It shall be appreciated that armature coupler  365  may take any shape and have any form and type of various indentations, outdents, apertures, posts, slots, and etc. to facilitate attachment to a table mount arm whether in a snap on quick connect style as illustrated in the corresponding FIGS. or by, for example, a clamp on ratcheting style or even a mushroom expansion style. 
       FIG. 126  is a perspective view of a modular retractor system including the quick connect couplers of  FIGS. 124-125 .  FIG. 127  is a top down view of the system of  FIG. 126 . Consistent with the disclosure herein, modular retractor  530  is securely coupled to a secondary module, e.g., module  1200 . Module  1200  may have the same, similar, and/or substantially the same features and functionality as the various other secondary modules discussed above. However, in this embodiment, secondary module  1200  is capable of linearly extending a centrally disposed first arm and a C shaped second arm, for example. In this embodiment, the C shaped second arm is supporting a free hand module  900  and the first arm is securely connected to a quick connect arm  360  via a table mount quick release coupler  533 , for example. Additionally, a body portion of module  1200  includes a table mount quick release coupler  533  and the second C shaped arm includes a table mount quick release coupler  533 . Additionally, it is shown that modular retractor  530  is securely connected to a quick connect coupler  360  at the table mount quick release coupler  533 . Accordingly, various modular retractor systems may comprise a plurality of quick release couplers  533  whether they be on the primary retractor  530  or secondary module  1200 , for example. In this way, a surgeon has maximum flexibility in attaching the modular retractor system to a table mount.  FIG. 128  is a perspective view of module  1200  in an uncoupled position with respect to modular retractor  530 .  FIG. 129  is a perspective view of module  1200  coupled to modular retractor  530 . In the example embodiment, retractor mount coupler  280  is secured to attachment rail  264  of the modular blade  260  and extendable blade  262 . Additionally, the retractor mount coupler  280  is coupled to lateral arm  1201  of retractor module  1200 . 
       FIG. 130  is a top down view of modular retractor  530  supporting first and second blades and module  1200  supporting a third blade.  FIG. 131  is a perspective view of three blades being slidably coupled to a dilator  94 . With reference back to the set of dilators  99  disclosed in  FIGS. 80C, 80B, 80E , and  FIG. 81  an example method of use will be disclosed. In a first step, a surgeon may insert an initial dilator or pin, e.g., innermost dilator  98 . In some embodiments, and depending on the particular surgical approach dilator  98  may be insert into a patient from a lateral, anterior, or trans psoas approach, e.g. Once the initial dilator  98  is insert in the patient, a dilator having a relatively wider size may be insert over the initial dilator  98 , e.g., dilator  97 . After dilator  97  is slipped over innermost dilator  98 , a dilator having a relatively wider size than dilator  97  may be slipped over dilator  97 , e.g., dilator  96 . Any number of successive and iteratively increasing in size dilators may be slipped over one another in this process. Thereafter, an outermost dilator  94  having a plurality of rail portions  94 A may be slipped over the immediately prior dilator, e.g., dilator  96 . 
     Next, a surgeon may position modular retractor  530  and retractor module  1200  over the outermost dilator  94 . For example, a surgeon may install first and second blades to the first and second arms of modular retractor  530  and a third blade may be installed on the proximal arm of retractor module  1200 . The three blades may be collapsed such that edge portions contact one another and a circular void space is formed by the interior surfaces of the three blades. Next, the surgeon may slip the three blades over the outermost dilator  94  such that the corresponding channel portions of the blades slidably couples to the rail portions  94 A of the outermost dilator, see  FIG. 81 . Thereafter, the surgeon may move the modular retractor  530  and retractor module  1200  such that the blades slide down along the length of outermost dilator and into the operative corridor. Once the surgeon has moved the three blades into the operative corridor, and the blades are supporting adjacent tissue, the surgeon may remove the outermost dilator  94 . After the outermost dilator  94  has been removed, the surgeon can freely manipulate any one of the three blades in any manner or relative movement as previously explained to enlarge the operative corridor. 
     Additional Retractor Embodiments 
     Referring generally to  FIGS. 132-142  an example modular retractor system including a modular retractor  530 , a fifth module  1100 , first and second freehand modules  900 , a cannula  1130 , a blade  1140 , and a support module  1150  are disclosed. In various embodiments, modular retractor  530 , and fifth module  1100  may include the same, substantially the same, and/or similar components and functionality as the above disclosed retractor embodiments. Accordingly, those with skill in the art will understand the general principles, modes of operation, and associated methods of each example embodiment may be combined and/or modified in view of the skill of a person of ordinary skill in the art. The embodiments and methods shown in  FIGS. 132-142  may be adapted for a cervical tissue retraction procedure and/or for performing a distraction of a disc space in the cervical portion of the spine, e.g., by spreading apart adjacent vertebrae and/or adjusting an alignment of the adjacent vertebrae. It shall be understood that the embodiments and methods are not limited to applicability of the cervical portion of the spine and may also be applied to other portions of human anatomy, e.g., the thoracic and/or lumbar areas of the spine and even other boney anatomy not associated with the spine. 
       FIGS. 132-135  are perspective views of a cervical modular retractor system  1300  during use. In the example embodiment, modular retractor  530  is securely connected to fifth module  1100  in the same, similar, or substantially the same way as disclosed above. Table mount system  340  may be securely coupled to and uncoupled from modular retractor  530  and/or fifth module  1100  at various attachment locations similarly as explained above.  FIG. 133  illustrates a top down view of modular retractor system  1300  with the table mount system  340  removed for ease of explanation. As illustrated, a plurality of support modules  1150  are removably coupled to modular retractor  530  and fifth module  1100 . A first support module  1150  is attached to arm  507  of modular retractor  530 ; and a second support module  1150  and third support module  1150  are attached to arm  1105  of fifth module. As explained in further detail below in conjunction with  FIG. 141 , support modules  1150  may be used to support a lighting system, an endoscope system, and/or a camera system. 
       FIG. 134  is a top down view of a modular retractor system  1300  with the support modules  1150  removed for ease of understanding. As illustrated, the surgical approach is from a lateral perspective towards a cervical portion of the spine (see  FIG. 142 ). In various embodiments, a first pin delivery cannula  1130  may be removably coupled to arm  505  and a second pin delivery cannula  1130  is removably coupled to arm  507  of modular retractor  530 . A first free hand module  900  is secured to distal module mount  1109 D and a second free hand module  900  is secured to proximal module mount  1109 P, for example. A cervical blade  1140  is releasably coupled to each of the free hand modules  900 , for example. 
       FIG. 135  is an enlarged top down view of region  1199  of  FIG. 134 . In the example embodiment, the first pin delivery cannula  1130  is positioned above a first vertebrae  1  and the second pin delivery cannula  1130  is positioned above a second vertebrae  2  adjacent to the first vertebrae  1 . In this embodiment, the first and second pin delivery cannulas  1130  are generally aligned with a centerline of a caudal to cephalad extension direction of the spine (see  FIGS. 142, 143 ). The first cervical blade  1140  and second cervical blade  1140  are positioned on opposite lateral sides of the first vertebrae  1  and second vertebrae  2  at a position that approximates the disc space between the first vertebrae  1  and second vertebrae  2 , for example.  FIG. 136  illustrates the configuration of  FIG. 135  with the cervical portion of the spine removed for ease of visualizing the relative location of the pin delivery cannulas  1130  with respect to the cervical blades  1140 . 
       FIG. 137  is a perspective view of a pair of cervical blades for use with various modular retractor systems disclosed herein. In the example embodiment, cervical blade  1140  may be a relatively thin and low profile blade adapted for use in the cervical area of the spine, for example. A proximal end of cervical blade  1140  may include an engagement feature  1146  having the same, similar, or substantially the same functionality as explained above. Blade  1140  may have a substantially planar inside surface  1142  having a width that generally tapers from the proximal end to the distal end, for example. Additionally, the distal end may include a footed tip  1141  that is angled with respect to the planar inside surface  1142 . In various embodiments, the footed tip  1141  may include various prongs with gaps therebetween or it may be substantially solid. In this embodiment, engagement feature  1146  is configured for bottom loading in a blade coupling portion  535  shown in  FIG. 121B . In use, blade  1140  may securely couple to blade coupling portion  535  by sliding blade  1140  into channel  535 B while detent  537 A engages with detent receiving aperture  1147  (see  FIG. 121B ), for example. To remove blade  1140 , an end user may actuate the blade release mechanism which will pull detent  537 A out of the detent receiving aperture  1147  such that the blade  1140  may be slipped out. 
       FIG. 138  is a perspective view of a pin delivery cannula  1130 ,  FIG. 139  is a perspective view of a pin  1160  for use with the pin delivery cannula  1130  and  FIG. 140  is a perspective view of the pin delivery cannula  1130  and pin  1160  in an example operative configuration. In various embodiments, the pin  1160  may be referred to as a screw, bone screw, or bone anchor, for example. In the example embodiment, pin delivery cannula  1130  may include an engagement feature  1136  having the same, similar, or substantially the same features as engagement feature  1146  explained above. Pin delivery cannula  1130  may include a cylindrical body portion  1131  extending in a proximal to distal direction that defines an internal shaft or aperture  1132  for receiving a pin  1160  therein. Pin  1160  may extend in a proximal to distal direction from a drive feature  1161  to a tip portion  1163 , for example. A smooth portion  1164  of various lengths and a threaded portion  1162  may be included between drive feature  1161  and tip portion  1163 . Threaded portion  1162  may comprise any type of suitable thread pattern or patterns. In other embodiments a threaded portion  1162  may not be included. As seen best in  FIG. 140 , pin  1160  may be inserted within the aperture  1132  of pin receiving cannula  1130 . In operation, a surgeon may rotate pin  1160  within aperture  1132  thereby driving pin  1160  forward into a bone structure, for example vertebrae  1  of  FIG. 135 , such that the threaded portion  1162  and tip  1163  extend beyond a distal end of the pin receiving cannula and are socketed into the boney structure. 
       FIG. 141  is a perspective view of a support module  1150  for attaching to arm portions of various modular retractor systems disclosed herein. In the example embodiment, support module includes a ball and socket mechanism  1151  supporting a light source  1152 , for example a light emitting diode (LED). In various embodiments, ball and socket mechanism may allow for the free range of movement of light source  1152  to pivot left, right, up, and down by about 5 degrees to about 15 degrees. In one embodiment, ball and socket mechanism allows for the free range of movement of light source  1152  by about six degrees. Support module  1150  may include a body portion  1159  having a slot  1157  which a coupling portion  1158  may slide forward and backward in, for example. Coupling portion  1158  may include a U-shaped clamp defining a cavity  1156 , for example. A lower portion  1154  of the U-shaped clamp may include a spring tab  1155  so that a corresponding arm may be quick snapped to support module  1150  by positioning the arm within cavity  1156 , for example. The support module  1150  may be secured to a corresponding arm by tightening knob  1153  which may pull the U-shaped clamp upward such that lower portion  1154  moves upward and applies a compressive force to the underside of a corresponding arm. Additionally, in various embodiments, when knob  1153  is not fully tightened the body portion  1159  may freely rotate with respect to the coupling portion and vice versa. 
       FIG. 142  is an example flow chart method of use of disclosed modular retractor systems.  FIG. 143  is a reference drawing showing the human spine of which various disclosed implant embodiments may be installed in.  FIG. 144  is a reference drawing showing various planes and reference directions of which the various disclosed implant embodiments may move in or act in with reference to a patient P. 
     An example method of use  1400  shown in  FIG. 142  will now be explained with reference back to  FIG. 133  and  FIG. 135 . At step  1402 , a modular retractor system may be provided, e.g., system  1300 . The modular retractor system  1300  may optionally be coupled to a table mount  340  and positioned in a lateral orientation for performing a surgery to a cervical portion of the spine, for example. At step  1404 , at least one pin receiving cannula may be attached to an arm of the modular retractor. For example, a first pin receiving cannula  1130  may be attached to a first arm  507  of modular retractor  530  and a second pin receiving cannula  1130  may be attached to a second arm  505  of modular retractor  530 . With reference to  FIG. 133 , the first pin receiving cannula  1130  attached to first arm  507  may be referred to as a cephalad pin receiving cannula and the second pin receiving cannula  130  attached to the second arm  505  may be referred to as a caudal pin receiving cannula although these may be reversed depending on whether the patient is approached from a left lateral side or a right lateral side. At step  1406 , at least one blade may be attached to the modular retractor system  1300 . For example, a first cervical blade  1140  may be attached to a first free hand module  900  coupled to proximal mount  1109 P and a second cervical blade  1140  may be attached to a second free hand module  900  coupled to distal mount  1109 D. At step  1408 , a pin may be disposed in the pin receiving cannula and then rotated and/or driven. For example, a first pin  1160  may be disposed in aperture  1132  of a first pin receiving cannula  1130  and a second pin  1160  may be disposed in aperture  1132  of a second pin receiving cannula  1130 . Thereafter, at least one or both pins  1160  may be driven and/or rotated at their respective drive ends  1161 . At step  1410 , the pin may be securely connected to a bone structure. For example, first pin  1160  may be positioned over a first vertebra  1  and second pin  1160  may be positioned over a second vertebra  2  and by driving or rotating pins  1160  they may penetrate into and/or thread into the respective vertebra thereby securely coupling the respective pin  1160  and pin receiving cannula  1130  to the corresponding vertebrae  1 ,  2 . At step  1412 , a disc space between adjacent vertebra may be distracted and/or enlarged. For example, the first arm  507  and second arm  505  may be actuated such that they spread apart from one another thereby moving one vertebra in a caudal direction and moving the other vertebra in a cephalad direction. Consistent with the disclosure herein, the first arm  507  and second arm  505  may be spread apart by squeezing the handles or by rotating actuator  502 , for example. At step  1414 , an angulation of a vertebra may be adjusted. For example, a pivoting member  505   b  and/or a pivoting member  505   c  may angulate the corresponding pin receiving cannular  1130  to adjust an angle of inclination of the respective vertebra in the sagittal plane. Those with skill in the art will readily understand that method  1400  may be modified to perform other surgeries in other parts of the body, e.g., lumbar and/or thoracic. Similarly, method  1400  may be applied to any type of surgical approach, e.g., lateral, posterior, anterior, oblique, etc. approaches for distracting and/or adjusting different vertebra in different planes of the body. Additionally, steps  1402 - 1414  may be performed in any order and additional intermediate steps consistent with the operation of disclosed retractor systems may also be performed. 
     It should be understood that various aspects disclosed herein may be combined in different combinations than the combinations specifically presented in the description and accompanying drawings. For example, features, functionality, and components from one embodiment may be combined with another embodiment and vice versa unless the context clearly indicates otherwise. Similarly, features, functionality, and components may be omitted unless the context clearly indicates otherwise. It should also be understood that, depending on the example, certain acts or events of any of the processes or methods described herein may be performed in a different sequence, may be added, merged, or left out altogether (e.g., all described acts or events may not be necessary to carry out the techniques). 
     Unless otherwise specifically defined herein, all terms are to be given their broadest possible interpretation including meanings implied from the specification as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc. It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless otherwise specified, and that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof