Patent Publication Number: US-2021186477-A1

Title: Retractor Members, And Related Systems And Methods

Description:
TECHNICAL FIELD 
     The present invention relates to retractor members for retracting soft tissue at a surgical treatment site within patient anatomy, as well as to systems and methods related to positioning the retractor members relative to an access tube. 
     BACKGROUND 
     Access tubes and/or retractors can be used to provide a physician with an access portal or “working channel” to a surgical treatment site within patient anatomy. Various minimally invasive procedures, including spinal procedures such as decompression, fusion, external fixation, and the like, may be performed through such access portals. The access tubes used in these procedures must often be secured in position relative to the treatment site via external devices, such as operating table-mounted devices and/or anatomical-mounted devices, such as bone anchors, including pedicle anchors and the like, by way of non-limiting examples. Once the access tube is positioned relative to the patient anatomy so as to provide the working channel open to the target treatment site, retractor members (also referred to as “retractor blades” or simply “blades”), can be inserted through the working channel and manipulated to engage soft tissue at the treatment site and pull the soft tissue toward the wall of the access tube. Additional retractor members can be inserted through the working channel as needed to pull additional soft tissue at the treatment site toward the wall of the access tube. In this manner, soft tissue can be retracted from the treatment site, providing the physician with increased access to and visualization of the treatment site, including visualization of the exiting nerve. However, during a surgical procedure, some of the soft tissue can tend to move or “creep” into the distal opening of the access tube, which can impede visualization of the treatment site, including visualization of the exiting nerve. 
     SUMMARY 
     According to an embodiment of the present disclosure, a retractor member that is configured for insertion through a channel of an access member and for moving soft tissue at a treatment site accessible through the channel includes a body having a proximal end and a distal end and spaced from each other along a longitudinal direction. The distal end defines a retractor blade and the body defines a first surface and a second surface opposite each other along a transverse direction substantially perpendicular to the longitudinal direction. The retractor includes an attachment device configured to selectively attach the body to a portion of the access member such that the body is extendable through the working channel and is translatable relative to the access member along the longitudinal direction while the body is attached to the portion of the access member. 
     According to another embodiment of the present disclosure, a system for retracting soft tissue includes an access member having a proximal end and a wall that extends from the proximal end to a distal end of the access member. The wall extends about a central axis in a plane orthogonal to the central axis such that an inner surface of the wall defines a channel that extends along an axial direction oriented along the central axis. The system includes a retractor body having a proximal end and a distal end that is configured to engage soft tissue and is spaced from the proximal end of the retractor body along a longitudinal direction. The retractor body defines a first surface and a second surface opposite each other along a transverse direction substantially perpendicular to the longitudinal direction. The system includes an attachment device that is coupled to the retractor body and includes a proximal mount and a distal mount configured to respectively mount to the proximal and distal ends of the access member. At least one of the proximal and distal mounts is configured to move between an unlocked configuration, in which the proximal and distal mounts are longitudinally spaced from each other by a first distance, and a locked configuration, in which the proximal and distal mounts are longitudinally spaced from each other by a second distance less than the first distance. The second distance corresponds to a distance between the proximal and distal ends of the access member along the axial direction. 
     According to an additional embodiment of the present disclosure, a system for retracting soft tissue includes an access member having a proximal end and a wall that extends from the proximal end to a distal end of the access member. The wall extends about a central axis in a plane orthogonal to the central axis such that an inner surface of the wall defines a channel that extends along an axial direction oriented along the central axis. The system includes a retractor body having a proximal end and a distal end that is configured to engage soft tissue and is spaced from the proximal end of the retractor body along a longitudinal direction. The retractor body defines a first surface and a second surface opposite each other along a transverse direction substantially perpendicular to the longitudinal direction. At least one of the access member and the retractor body defines one or more openings, while the other of the access member and the retractor body includes one or more protrusions that are complimentary with the one or more openings and are configured for insertion within the one or more openings so as to couple the retractor body to the access member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing summary, as well as the following detailed description of illustrative embodiments of the present application, will be better understood when read in conjunction with the appended drawings. For the purposes of illustrating the structures of the present application, there is shown in the drawings illustrative embodiments. It should be understood, however, that the application is not limited to the precise arrangements and instrumentalities shown. In the drawings: 
         FIG. 1A  is a perspective view of a spinal surgical system that includes a surgical access system, according to an embodiment of the present disclosure; 
         FIG. 1B  is another perspective view of the spinal surgical system illustrated in  FIG. 1A , showing working channel of a tubular access member of the surgical access system; 
         FIG. 1C  is a perspective view of the surgical access system illustrated in  FIG. 1B , showing a retractor disposed within the working channel of the access member, in which a proximal portion of the retractor is bent relative to a distal portion of the retractor and away from the working channel, according to an embodiment of the present disclosure; 
         FIG. 1D  is a partial top view of the access member illustrated in  FIG. 1C  having a retractor affixed to an inner wall surface of the access member; 
         FIG. 2A  is a perspective view of a retractor that includes has straight ends and includes a flexible attachment spring for securing the retractor to the inner wall surface of the access member illustrated in  FIGS. 1A-1C , according to an embodiment of the present disclosure; 
         FIG. 2B  is a perspective view of a retractor having angularly offset ends and being otherwise similar to the retractor illustrated in  FIG. 2A , according to an embodiment of the present disclosure; 
         FIG. 2C  is a partial side view of the retractor illustrated in  FIG. 2B ; 
         FIG. 2D  is a perspective view of a retractor having flared ends and being otherwise similar to the retractor illustrated in  FIG. 2A , according to an embodiment of the present disclosure; 
         FIG. 2E  is a perspective view of a retractor having flared and angular offset ends and being otherwise similar to the retractor illustrated in  FIG. 2A , according to an embodiment of the present disclosure; 
         FIG. 2F  is a perspective view of a retractor having flexible attaching spring and proximal and distal portions that are circumferentially offset from each other along the attachment spring; 
         FIG. 2G  is a perspective view of a retractor defining a plurality of apertures; 
         FIG. 3A  is a perspective view of a surgical access system having an access member and a retractor, which has a guide feature for guiding movement of a separate attachment spring; 
         FIG. 3B  is a perspective view of the surgical access system illustrated in  FIG. 3A , showing the attachment spring connected to the guide feature of the retractor in a position remote from the access member; 
         FIG. 3C  is a perspective view of the surgical access system illustrated in  FIG. 3B , showing the attachment spring advanced distally along the guide feature to a position within the working channel of the access member, in which the attachment spring pushes the retractor securely against the inner wall surface of the access member; 
         FIG. 3D  is a partial sectional perspective view of a surgical access system having an access member, a retractor, and a separate attachment spring having carrying one or more magnets for magnetic attachment to the retractor, according to an embodiment of the present disclosure; 
         FIG. 4A  is a perspective view of a surgical access system including an instrument in a coupled configuration with an attachment device of a retractor, in which configuration the instrument can manipulate the retractor for engaging and retracting soft tissue accessible through the working channel, further illustrating the attachment device in a locked configuration with the access member, the attachment device being operable by the instrument for attaching the retractor to a select circumferential location of the access member, the attachment device being further configured to allow longitudinal translation of the retractor relative to the access member while the attachment device is in the locked configuration, according to an embodiment of the present disclosure; 
         FIG. 4B  is another perspective view of the surgical access system illustrated in  FIG. 4A  in the coupled and locked configurations; 
         FIG. 4C  is a side view of a portion of the instrument illustrated in  FIG. 4A , showing a portion of a coupling mechanism of the instrument in the coupled configuration with the attachment device and further showing a proximal mount of the attachment device in the locked configuration with the access member; 
         FIG. 4D  is a side view of the portion of the instrument illustrated in  FIG. 4C , showing the portion of the coupling mechanism in a de-coupled configuration, in which the instrument is uncoupled from the attachment device, further showing the proximal mount remaining in the locked configuration with the access member; 
         FIG. 4E  is a sectional side view of the surgical access system illustrated in  FIG. 4A , showing iteration of the proximal mount between the locked configuration and an unlocked configuration with respect to the access member; 
         FIG. 4F  is a sectional perspective view of a bias mechanism of the attachment device illustrated in  FIG. 4A ; 
         FIG. 4G  is a sectional perspective view of the coupling mechanism of the instrument illustrated in  FIG. 4A ; 
         FIG. 4H  is a sectional perspective view of the coupling mechanism illustrated in  FIG. 4A ; 
         FIG. 4I  is a sectional perspective view of the attachment device de-coupled from the instrument illustrated in  FIG. 4A , showing the retractor being longitudinally translatable relative to the attachment device and the access member; 
         FIG. 4J  is a perspective view of the attachment device illustrated in  FIG. 4I , showing guide features for guiding the translation of the retractor relative to the access member; 
         FIG. 4K  is another perspective view of the guide features illustrated in  FIG. 4J ; 
         FIG. 5A  is a perspective view of another embodiment of an instrument releasably coupled to a retractor, in which the instrument couples directly to the retractor, the retractor carries an attachment device for attaching the retractor to a select circumferential location of the access member, and the attachment device is operable independently from the instrument; 
         FIG. 5B  is a sectional perspective view of a coupling mechanism of the instrument taken along section line  5 B- 5 B illustrated in  FIG. 5A ; 
         FIG. 6A  is a side plan view of another embodiment of an instrument releasably coupled to a retractor, in which the retractor includes an attachment device that employs a tensile actuator for attaching the retractor to a select circumferential location of the access member; 
         FIG. 6B  is a rear plan view of a distal mount of the attachment device illustrated in  FIG. 6A , in which the distal mount is actuated by the tensile actuator; 
         FIG. 6C  is a perspective view of the attachment device illustrated in  FIG. 6A ; 
         FIG. 6D  is a side plan view of a surgical access system, showing the instrument, retractor, and attachment device of  FIG. 6A  attached to an access member; 
         FIG. 6E  is a perspective view of a proximal mount of the attachment device illustrated in  FIG. 6A , showing the proximal mount having receiving formations for receiving the tensile actuator; 
         FIG. 6F  is a bottom plan view of the distal mount and the retractor blade illustrated in  FIG. 6B ; 
         FIG. 7A  is a perspective view of a retractor having an attachment device having a handle member and employing a ratchet mechanism, according to an embodiment of the present disclosure; 
         FIG. 7B  is a perspective view of another embodiment of the handle member illustrated in  FIG. 7A ; 
         FIG. 7C  is a sectional perspective view of the attachment device taken along section line  7 C- 7 C illustrated in  FIG. 7A ; 
         FIG. 7D  is a perspective view of retractor and attachment device illustrated in  FIG. 7A ; 
         FIG. 7E  is a sectional perspective view of the retractor and attachment device taken along section line  7 E- 7 E illustrated in  FIG. 7D ; 
         FIG. 7F  is a perspective view of the ratchet mechanism illustrated in  FIG. 7A ; 
         FIG. 7G  is a rear plan view of a pawl of the ratchet mechanism illustrated in  FIG. 7A , with the handle member sectioned for visibility purposes; 
         7 H is a sectional perspective view of the pawl taken along section line  7 H- 7 H illustrated in  FIG. 7G ; 
         FIG. 8A  is a sectional view of a retractor having a suction attachment device for attaching the retractor to a select circumferential location of the access member, according to an embodiment of the present disclosure; 
         FIG. 8B  is a rear plan view of the retractor illustrated in  FIG. 8A ; 
         FIG. 8C  is a sectional end view of the retractor taken along section line  8 C- 8 C illustrated in  FIG. 8B ; 
         FIG. 9A  is an exploded, partial sectional view of a surgical access system having an attachment device that includes protrusions and complimentary openings configured for selective mating engagement to attach the retractor to a select circumferential location of the access member, according to an embodiment of the present disclosure; 
         FIG. 9B  is a sectional side view showing mating engagement between a protrusion and opening illustrated in  FIG. 9A ; 
         FIG. 9C  is a sectional side view showing an alternative mating engagement between a protrusion and opening illustrated in  FIG. 9A ; 
         FIG. 9D  is a perspective view of an access member having a proximal surface and a series of protrusions arranged circumferentially along the proximal surface for selective mating engagement with a complimentary opening in a retractor; 
         FIG. 9E  is a sectional side view of a retractor near mating engagement with the access member illustrated in  FIG. 9D ; 
         FIG. 10A  is a partial sectional view of a surgical access system that includes an introducer for inserting a flexible wire attachment device, shown in an insertion configuration, into the working channel of an access member, according to an embodiment of the present disclosure; 
         FIG. 10B  is a sectional view of the surgical access system illustrated in  FIG. 10A , showing the flexible wire attachment device in a deployed configuration in which the flexible wire attachment device secures the retractor to an inner wall surface of the access member; 
         FIG. 10C  is a front view of another embodiment of a flexible wire attachment device loaded in an introducer in an insertion configuration; 
         FIG. 10D  is a front plan view of the flexible wire attachment device illustrated in  FIG. 10C , shown in a deployed configuration; 
         FIG. 11A  is a front plan view of a retractor having an electrically insulative sheath and also having a sensor for obtaining electrical information at a surgical treatment site; 
         FIG. 11B  is a front plan view of a retractor constructed of an electrically insulative material and having a sensor for obtaining electrical information at a surgical treatment site; 
         FIG. 12A  is perspective view of an instrument carrying a retractor that includes a tether, according to another embodiment of the present disclosure; 
         FIG. 12B  is a perspective view of the retractor illustrated in  FIG. 12A ; 
         FIG. 12C  is a perspective view of the retractor having an alternative tether, according to another embodiment of the present disclosure; 
         FIG. 12D  is a perspective view of a surgical access system employing the retractor shown in  FIG. 12A , the surgical access system having receiving formations for connection to the tether, according to an embodiment of the present disclosure; and 
         FIG. 12E  is a perspective view of the surgical access system shown in  FIG. 12D  having a retention clip for connection to the tether, according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     The present disclosure can be understood more readily by reference to the following detailed description taken in connection with the accompanying figures and examples, which form a part of this disclosure. It is to be understood that this disclosure is not limited to the specific devices, methods, applications, conditions or parameters described and/or shown herein, and that the terminology used herein is for the purpose of describing particular embodiments by way of example only and is not intended to be limiting of the scope of the present disclosure. Also, as used in the specification including the appended claims, the singular forms “a,” “an,” and “the” include the plural, and reference to a particular numerical value includes at least that particular value, unless the context clearly dictates otherwise. 
     The term “plurality”, as used herein, means more than one. When a range of values is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. All ranges are inclusive and combinable. 
     The terms “approximately” and “substantially”, as used herein with respect to dimensions, angles, and other geometries, takes into account manufacturing tolerances. Further, the terms “approximately” and “substantially” can include 10% greater than or less than the stated dimension or angle. Further, the terms “approximately” and “substantially” can equally apply to the specific value stated. 
     The embodiments described below pertain to retractor members (also referred to herein as “retractors”) for use in a surgical access system that includes an access member, such as an access tube. In particular, the embodiments described below pertain to retractors configured for insertion through a working channel of the access member to engage and retract soft tissue at a surgical treatment site distally located from the working channel. More particularly, the embodiments described below include various attachment devices allowing selective attachment of the retractor to a circumferential location of the access tube, thereby securing the soft tissue in a retracted position. As used herein with reference to an access member, the term “circumferential” generally refers to a direction revolving around a central axis of the access member, and specifically refers to any direction having a directional component that is offset from both (1) a radial direction perpendicular to the central axis and (2) an axial direction along which the central axis extends. Thus, the term “circumferential,” as used herein with reference to an access member, refers to a direction along any of a line, an arc, a circle, an ellipse, a polygon, or an irregular shape, that revolves at least partially around the central axis of the access member. 
     Some of the attachment devices described below are located entirely on the retractor, while others are employed in complimentary components or features of the retractor and the access member, while yet others are employed is a separate component of the surgical access system. Additionally, a majority of the attachment devices described below allow the retractor to move in the following ways relative to the access member, while yet remaining secured to an inner wall surface thereof: translation along an axial direction oriented along a central axis of the member; and rotation (i.e., revolution) about the central axis circumferentially along the inner wall surface. These movements allow the physician to adjust the retractor position within the working channel as needed to account for variations in patient anatomy (e.g., variations between the anatomies of different patients). Such retractors and complimentary attachment devices that are moveable in any of the foregoing ways can also be repositioned during a surgical procedure to adjust the retraction of soft tissue as needed, while yet remaining attached to the inner wall surface so that when the physician has repositioned the retractor to satisfaction, the attachment device will hold the position of the retractor relative to the access member after the physician releases the retractor. 
     In additional embodiments described below, the retractor is employed as part of a surgical access system that includes an instrument coupled to a proximal end of the retractor and configured for manipulating the retractor to engage soft tissue. The instruments described below are configured to selectively couple with and de-couple from the retractor as needed. In further embodiments, the insertion instrument is also configured to actuate the attachment device from an un-attached configuration, in which the attachment device is un-attached to the access member, to an attached configuration, in which the attachment device attaches the retractor to the access member, as described above. 
     Referring now to  FIG. 1A , an exemplary embodiment of a surgical access system  100  for a spinal procedure includes an access member  102  for providing access to a surgical treatment site within the patient and a retractor member  2  configured to extend through the access member  102  and engage soft tissue at the treatment site. The access member  102  has a body  103 , which can be tubular, and is configured to extend distally from an ex vivo location with respect to patient anatomy to an in vivo target location within the patient anatomy. By way of a non-limiting example, the access member  102  can be configured to extend through the skin line  90  and to the target location, which is at or adjacent an intended surgical treatment site. The access member  102  includes a shield or wall  104  that defines an internal port or channel  106 , also referred to herein as a “working channel”  106 , that is elongate along a central axis  108  of the access member  102  and is open from the ex vivo location to the target location along an axial direction X (i.e., the direction oriented along the central axis  108 ). The access member  102  extends from a proximal end  110  to a distal end  112  along the axial direction X. In the illustrated example, the central axis  108  defines a spinal approach axis, which is oriented along a transforaminal approach, such as through the Kambin&#39;s triangle. In this example, the target location of the access member  102  is at the facet line  92  of adjacent vertebral bodies  94 , and the treatment site includes the intervertebral disc space  96 . It should be appreciated, however, that other approaches are within the scope of the present disclosure, including but not limited to interlaminar, lateral, and anterior approaches. With the access member  102  positioned at the proper depth and orientation so as to extend to the treatment site, the central axis  108  intersects the treatment site. In this manner, instrumentation can be advanced distally through the access member  102  toward the treatment site as needed. To prepare the treatment site for certain instruments, one or more retractor members  2  can be inserted through the working channel  106 , such as along the central axis  108 , and can be manipulated to engage and retract soft tissue (including soft tissue near the exiting nerve), such as by pulling or otherwise moving the soft tissue along a radial direction R away from and substantially perpendicular to the central axis  108  (and thus also substantially perpendicular to the axial direction X). If a portion of the engaged soft tissue extends within the working channel, the retraction moves such soft tissue toward the wall  104  of the access member  102 . The retraction of soft tissue can be employed, among other things, to expose and provide visualization of the exiting nerve so that the physician can avoid damaging or contacting the exiting nerve during the spinal procedure. 
     The surgical access system  100  can be employed as a sub-system of a primary surgery system  200 , such as a spinal surgery system. With respect to the spinal surgical procedure depicted, the spinal surgery system  200  can include, among other things, a connector  202  having one or more arms  204  for connecting the access member  102  to an anchor, such as a pedicle anchor, such as a contra-lateral pedicle anchor  206 , as shown. In this manner, the position of the access member  102  and its working channel  106  can be affixed relative to the patient anatomy, such as via the anchor  206  and the connector  202 . The spinal surgery system  200  can be configured as more fully described in U.S. Patent Publication No. 2018/0008253 A1, published Jan. 11, 2018, entitled “MULTI-SHIELD SPINAL ACCESS SYSTEM” (“the &#39;253 Reference”); and U.S. patent application Ser. No. 16/692,342, filed Nov. 22, 2019, entitled “CONTROL MEMBER FOR ADJUSTING ACCESS TUBE POSITION, AND RELATED SYSTEMS AND METHODS” (“the &#39;342 Reference”), the entire disclosure of each of which is incorporated by reference herein. 
     Referring now to  FIGS. 1B through 1D , the wall  104  of the access member  102  defines an outer wall surface  114  and an inner wall surface  116  spaced from each other along the radial direction R. As shown, the outer wall surface  114  can have an oblong profile in a plane orthogonal to the central axis  108 . Additionally, the wall  104  can also define a secondary channel  107  along the axial direction X. For example, the inner wall surface  116  can define one or more projections  117  that extend generally radially inward toward the central axis  108  so as to define a partition between the working channel  106  and the secondary channel  107 . In the illustrated embodiment, the secondary channel  107  can receive one or more optical instruments, such as a camera or other type of image sensor, by way of non-limiting examples. In such embodiments, the partition between the working channel  107  and the secondary channel  107  is helpful for preventing mechanical interference between the optical instrument(s) and any instruments extending through the working channel  106 . The secondary channel  107  is preferably open to the working channel  106  at least along a direction having a directional component along the radial direction R. As shown, the wall  104  can extend an entire revolution about the central axis  108 , thereby providing the access member  102  with its tubular configuration. It should be appreciated, however, that the wall  104  can extend less than a full revolution about the central axis  108 , while continuing to provide a working channel  106  and optionally also a secondary channel  107 . 
     As shown in  FIG. 1C , the retractor member  2  (also referred to herein as a “retractor”  2 ) has a retractor body  3  that extends from a proximal end  4  to a distal end  6  spaced from each other along a longitudinal direction L. It should be appreciated that the retractor body  3  can define the entire retractor  2  in monolithic fashion, or can define a portion of the retractor  2 , such as a major portion thereof in combination with one or more separate yet connected (or connectable) portions of the retractor  2 , by way of non-limiting examples. The distal end  6  can have a blade-like geometry, and can thus be referred to as a “retractor blade” or simply a “blade”. The retractor  2  has a length along the longitudinal direction L greater than a length of the access member  102  along the axial direction X. In this manner, the retractor  2  can be inserted through the working channel  106  to the treatment site and can be manipulated by its proximal end  4  so as to control placement of the distal end  6  to engage soft tissue as needed at or near the treatment site. It should be appreciated that the proximal end  4  can also have a blade-like geometry and can thus also be referred to as a “retractor blade” or “blade”. Such opposed-blade configurations can be advantageous because they need not require a specific end to be inserted through the access member  102 . 
     With the soft tissue engaged, the retractor  2  can be moved to the inner wall surface  116  and attached thereto by an attachment device, described in more detail below. As shown in  FIG. 1D , the retractor body  3  has a first or “inner” surface  10  and a second or “outer” surface  12  spaced from each other along a transverse direction T substantially perpendicular to the longitudinal direction L. The outer surface  12  of the retractor body  3  is preferably arcuate and convex in a plane orthogonal to the longitudinal direction L. Additionally, the outer surface  12  preferably defines a radius R 1  substantially equivalent to a radius R 2  of the inner wall surface  116 . In this manner, the retractor body  3  can be moved flush against the inner wall surface  116  for connection thereto, so as to avoid obstructing the working channel  106 . It should be appreciated that when the retractor body  3  is flush against the inner wall surface  116 , the transverse direction T is substantially oriented along the radial direction R of the access member  102 . The inner surface  10  of the retractor body  3  is preferably arcuate and concave in the orthogonal plane, and preferably extends in parallel or concentric fashion with the convex outer surface  12  in the orthogonal plane. 
     The retractor  2  is formed of a material that is biocompatible (i.e., a “biomaterial”) and is sufficiently rigid so that manipulation at the proximal end  4  causes retraction of soft tissue at the distal end  6  (or vice versa if the opposite end is inserted through the working channel  106 ). The material also preferably provides the retractor body  3  with deformability, such as via plastic deformation, allowing a first portion  3   a  of the retractor body  3  to be bent relative to a second portion  3   b  of the retractor body, as shown in  FIG. 1C . In this manner, when retractor body  3  has achieved satisfactory retraction of soft tissue (and the retractor body  3  has been secured to the access member  102  by an attachment device, as described in more detail below), the physician can bend the first portion  3   a  away from the central axis  108  and out of the way, thereby reducing the profile of the retractor body  3  in a proximal direction P, for example. Such retractor body materials can be metal (e.g., stainless steel, such as a 300 series and/or a 400 series stainless steel), polymeric (e.g., polyphenylsulfone (PPSU)), and/or a composite material (e.g., carbon fiber), by way of non-limiting examples. 
     Referring now to  FIGS. 2A through 2F , different variants of the retractor body  3  are shown, each of which includes an integrated attachment device  14  for coupling the retractor body  3  to the wall  104  of the access member  102 . For example, the attachment device  14  is configured to attach the retractor body  3  to a circumferential portion of the inner wall surface  116  as selected by the physician. In particular, the attachment device  14  shown in each of these variants comprises at least one compliant member  16  configured to flex from a neutral configuration when disposed outside the working channel  106  to a flexed configuration when inserted within the working channel  106 . The compliant member  16  can also be referred to as a “locking spring” or “locking ring”. When in the flexed configuration, the compliant member  16  imparts a return force (which can also be referred to as a “locking force”) against the inner wall surface  116  sufficient to push the retractor body  3  toward the inner wall surface  116 , effectively securing the retractor body  3  in place relative to the wall  104 . It should be appreciated that the compliant member  16  is configured such that the locking force is sufficient to maintain retraction of soft tissue engaged by the distal end  6  of the retractor body  3 , yet not so great so as to prevent the physician from further subsequently manipulating the retractor body  3  to adjust engagement with soft tissue, such as to translate the retractor body  3  along the axial direction X, rotate the retractor body  3  about the central axis  108 , or any combination of the foregoing motions. Furthermore, the compliant member  16  of the present embodiments is configured to effectively automatically secure the retractor body  3  in place within the working channel  106  once the physician has finished manipulating the proximal end  4  thereof (so long as the compliant member  16  resides within the working channel  106 ). 
     Each of the retractor bodies  3  defines a first side  20  and a second side  22  spaced from each other along a lateral direction A substantially perpendicular to the longitudinal and transverse directions L, T. The compliant member  16  of the attachment device  14  can include a pair of compliant members  16  or “wings” that extend circumferentially outward from the first and second sides  20 ,  22  at a longitudinal portion  3   c  of the retractor body  3  that is intermediate the proximal and distal ends  4 ,  6  thereof. Thus, longitudinal portion  3   c  can also be referred to an “intermediate” portion  3   c  of the retractor body  3 . The retractor body  3  also defines a proximal body portion  3   d  that extends from the intermediate portion  3   c  to the proximal end  4  along the proximal direction P, and a distal body portion  3   e  that extends from the intermediate body portion  3   c  to the distal end  6  along a distal direction D. It should be appreciated that the proximal and distal directions P, D are each monodirectional components of the longitudinal direction L, which is bi-directional. A radially outer surface of the wings  16  defines a radius R 3  that is slightly larger than the radius R 2  of the inner wall surface  116  when in the neutral configuration. In this manner, inserting the wings  16  within the working channel  106  causes the wings  16  to flex inwardly toward the central axis  108  (and also toward one another), thereby providing the locking force. One or both of the wings  16  can define a helical end surface  18  that is contiguous with the respective first or second side  20 ,  22  of the retractor body  3 . In the illustrated embodiments, the helical end surface  18  defines a proximal surface of each wing  16 , although the distal surface of one or both of the wings  16  can also extend helically to the respective first or second side  20 ,  22  in similar fashion. 
     As shown in  FIGS. 2B and 2C , the retractor body  3  can define a proximal end portion  3   f  that is angularly offset from an adjacent portion  3   h  at an acute angle α 1 , as measured in a plane extending along the longitudinal and transverse directions L, T, which plane can be referred to as the “L-T plane”. The adjacent portion  3   h  can be characterized as a portion of the body  3  that extends from the end portion  3   f  toward the opposite end  6  of the retractor body  3 . The retractor body  3  can alternatively or additionally define a distal end portion  3   g  that is angularly offset from the adjacent portion  3   h  at an acute angle α 2  in the L-T plane. In embodiments where the retractor body  3  has proximal and distal end portions  3   f ,  3   g  that are angularly offset from the adjacent portion  3   h , the acute offset angles α 1 , α 2  can be substantially equivalent, as shown, or can be different from each other. 
     As shown in  FIG. 2D , one or both of the proximal and distal end portions  3   f ,  3   g  can be flared outwardly along the lateral direction A so as to define a maximum lateral dimension A 1 , A 2  that is greater than a maximum lateral dimension A 3  of the adjacent portion  3   h . In embodiments where both of the proximal and distal end portions  3   f ,  3   g  are flared outwardly along the lateral direction A, the maximum lateral dimensions A 1 , A 2  of the end portions  3   f ,  3   g  can be substantially equivalent, as shown, or can be different from one another. 
     As shown in  FIG. 2E , one or both of the proximal and distal end portions  3   f ,  3   g  can be both angularly offset from the adjacent portion  3   h  and flared outwardly along the lateral direction A relative to the adjacent portion  3   h . For example, both of the proximal and distal end portions  3   f ,  3   g  can be angularly offset from the adjacent portion  3   h  at the same acute angle or different acute angles and can also be flared outwardly to define the same or different maximum lateral dimension. It should be appreciated that the retractor body  3  can have proximal and distal end portions  3   f ,  3   g  that are any combination of the foregoing (i.e., straight, angled, and flared). 
     Referring now to  FIG. 2F , the proximal and distal body portions  3   d ,  3   e  can at least partially, and optionally entirely, circumferentially offset from each other. In such embodiments, the proximal body portion  3   d  can extend from the proximal end  4  in the distal direction D to the locking spring  16 , and the distal body portion  3   e  can extend from the locking spring  16  in the distal direction D to the distal end  6 . Additionally, in such embodiments, the locking spring  16  can include an interconnecting portion  16   a  that connects the proximal and distal body portions  3   d ,  3   e  together. 
     As shown in  FIG. 2G , the retractor body  3  can include one or more features for increasing the flexibility of the respective body portions thereof. By way of non-limiting examples, the retractor body  3  can define apertures  24  extending therethrough along the transverse direction T, such as for facilitating plastic deformation in the L-T plane, such as for bending a proximal portion  3   a  of the body  3  out of the way once secured to the wall  104 , as described above with reference to  FIG. 1C . For example, the apertures  24  can effectively define bend-enhancing regions of the retractor body  3 . Additionally or alternatively, one or both of the wings  16  can define an aperture  26  for increasing the flexibility of the wings  16 , such as for elastically deforming between the neutral and flexed configurations described above. One advantage of employing apertures  24 ,  26  for increased flexibility is that stronger materials can be used to form the retractor body  3 . Moreover, the apertures  26  can be elliptical in shape, which can alleviated material fatigue from multiple bends imposed at or near the same location of the retractor body  3 . Additionally, at one or both of the proximal and distal ends  4 ,  6 , the retractor body  3  can define an end formation  27  for connection to a wire, flexible tube, or other component or instrument of the surgical access system  100 . A non-limiting example of such an end formation  27  can include an aperture  28  and a prong  29  extending over the aperture  27 , such as along the longitudinal direction X. 
     It should be appreciated that the locking spring  16  of any of the foregoing embodiments can be provided at different longitudinal locations along the retractor body  3  to compensate for deflection responsive to the soft tissue engaged by the distal end  6  and/or other surrounding tissue in contact with the retractor  2 . For example, any combination of the retractors  2  described above with reference to  FIGS. 2A through 2G  can be provided in a kit that includes multiple versions of each retractor  2 , wherein the respective locking springs  16  are located at different longitudinal locations along the retractor body  3 . 
     It should further be appreciated that the designs of the retractors  2  described above with reference to  FIGS. 2A through 2G  allow more than one retractor  2 , such as two (2) or more retractors  2 , to be inserted within the working channel  106  and secured to the inner wall surface  116  for retracting soft tissue. When a second retractor  2  is inserted into a working channel  106  that already has a first retractor  2  attached thereto, the physician can select the second retractor  2  to be one in which its locking spring  16  will be longitudinally offset from that of the first retractor  2  when both are secured within the working channel  106 , thereby avoiding interference between the locking springs  16 . Additionally or alternatively, the physician can select the second retractor  2  to have the same design as the first, and can elect to insert the opposite end of the second retractor  2  into the channel  106  (i.e., can flip the second retractor  2  relative to the first retractor  2 ) so that the locking springs  16  do not interfere with each other. 
     Referring now to  FIGS. 3A through 3C , in other embodiments, the attachment device  14  can include an attachment member  17  that is separate from and connectable to the retractor  2 , such as before, during, or after the retractor  2  is inserted through the working channel  106 . In such embodiments, the retractor  2  and the attachment member  17  can have complimentary mounting formations. For example, the attachment member  17  can include a slide formation, such as a slider  30 , that is configured to slidably engage a complimentary slide formation, such as a guide slot  32 , of the retractor body  3 . The guide slot  32  of the present embodiment guides translational, longitudinal movement of the slider  30  (and thus also the attachment member  17 ) along the retractor body  3  into and out of the working channel  106  as needed. The slider  30  and the guide slot  32  preferably have complimentary geometries that allow the slider  30  to enter into the guide slot  32  and vacate the guide slot  32 , at least at one location of the guide slot  32 , such as at a proximal end thereof. For example, a proximal end of the guide slot  32  can have a widened portion or opening that allows entry and departure of the slider  30  therein, while the reminder of the guide slot  32  is configured to retain the slider  30  therein. A distal end of the guide slot  32  can effectively provide a physical stop that prevents the slider  30  (and thus also the attachment member  17 ) from over-translating in the distal direction D. 
     Similar to the embodiments described above, the attachment member  17  includes a locking member, such as a locking spring  16 , which can be configured similarly as described above. The locking spring  16  can define one or more compliant wings, each of which can be referred to as a circumferential wall that extends circumferentially away from the slide formation  30  and is configured to be flexed inwardly toward the central axis  108  of the access member  102  when the locking member  16  is disposed in the working channel  106  to supply the locking force. When inside the working channel  106 , the locking spring  16  can be positioned so as to slide annularly between the outer surface  12  of the retractor body  3  and the inner surface  116  of the access member  102 . The slider  30  can extend inwardly along the transverse direction T (i.e., toward the central axis  108  of the access member  102 ) from the locking spring  16  and into the guide slot  32 . In other embodiments, the slider  30  can extend transversely outwardly from the locking spring  16 , in which embodiments the retractor body  3  can be positioned annularly between the locking spring  16  and the inner wall surface  116 . The attachment member  17  includes a grip member, such as a proximal extension  34 , allowing the physician to manipulate the attachment member  17  along the longitudinal direction L relative to the retractor body  3 . It should be appreciated that the proximal extension  34  can be configured to be bent away from the central axis  108  and out of the way so as to reduce its profile in the proximal direction P, similar to the manner described above with reference to  FIG. 1C . 
     The retractor body  3  of the present embodiment can be freely inserted through the working channel  106  to engage soft tissue, and once so engaged, can then receive the attachment member  17 , which can be advanced along the guide slot  32  along the distal direction D until the locking spring  16  resides at a desired longitudinal location within the working channel  106 , at which position it provides the locking force. The longitudinal position of the attachment member  17  can thereafter be adjusted as needed, such as to reduce deflection of the retractor responsive to surrounding tissue. Furthermore, if a subsequent adjustment to the engagement between the distal end  6  of the retractor body  3  and the soft tissue is desired, the attachment member  17  can be withdrawn proximally from the working channel  106  while optionally remaining engaged with the guide slot  32 , and can be re-translated within the working channel  106  as needed, such as after the adjustment to the soft tissue is complete. In this manner, the attachment member  17  can be withdrawn from the working channel  106  during re-adjustments to the soft tissue retraction, allowing the physician greater freedom to manipulate the retractor body  3  as needed. 
     Referring now to  FIG. 3D , in other embodiments, the separate attachment member  17  and the retractor  2  can be configured for magnetic attachment to each other within the working channel  106 . For example, at least a portion of the locking spring  16  of the attachment member  17  can be constructed of a ferrous (e.g., magnetic) material, and the retractor  2  can include a series of magnets  35  for selective attachment to the attachment member  17  (or at least to the ferrous portion thereof). The attachment member  17 , including the locking spring  16  and the proximal extension  34  thereof, can otherwise be configured similarly as described above with reference to  FIGS. 3A through 3C . In the present embodiment, the attachment member  17  can be inserted within the working channel  106  and the retractor  2  can subsequently be inserted through the working channel  106  to engage and retract soft tissue. With soft tissue engaged, the physician can move the retractor  2  toward the inner wall surface  116  (and thus also toward the locking spring  16 ) and can bring a select one of the magnets  35  into magnetic engagement with the locking spring  16  (or at least with the ferrous portion thereof), thereby attaching the retractor to the inner wall surface  116 . In additional embodiments, the retractor  2  can be constructed of a ferrous material and the locking spring  16  can carry one or more magnets. In further embodiments, the retractor  2  and the locking spring  16  can carry opposite polarity magnets for attachment therebetween. 
     Referring now to  FIGS. 4A through 4D , the surgical access system  100  can include an instrument  300  that is releasably coupled to the retractor body  3  for manipulating the retractor body  3 , such as to engage and retract soft tissue with the distal end  6  thereof. The instrument  300  includes a handle  302  that extends along a forward direction FD from a rear end  304  of the instrument  300  to a coupling mechanism  308  at a front end  306  of the instrument  300 . The coupling mechanism  300  releasably couples the instrument  300  to the retractor body  3 . For example, the coupling mechanism  308  can be configured to iterate between a coupled configuration (shown in  FIGS. 4A through 4C ), in which the instrument  300  is rigidly coupled to the retractor body  3 , and a de-coupled configuration (shown in  FIG. 4D ), in which the instrument  300  is de-coupled and removable from the retractor body  3 , as described in more detail below. 
     The instrument  300  can also be configured to operate an attachment device  314  coupled to the retractor body  3 . As above, the attachment device  314  is configured to attach the retractor body  3  to the access member  102 , particularly to the inner wall surface  116  after the distal end  6  of the retractor body  3  has engaged the soft tissue to be retracted thereby. In the present embodiment, the attachment device  314  can have a proximal mount  316  and a distal mount  318  configured to respectively mount to the proximal and distal ends  110 ,  112  of the access member wall  104 . The proximal mount  316  defines one or more mating surfaces  317  configured to engage one or more complimentary mating surfaces  307  defined at the front end  306  of the instrument  300 . The mating surfaces  307 ,  317  can be aligned with the axial and longitudinal directions, respectively, allowing the instrument  300  to lift off of the proximal mount  316  along the longitudinal direction L when in the de-coupled configuration, as shown in  FIG. 4D . 
     Referring now to  FIG. 4E , the proximal and distal mounts  316 ,  318  can each include an engagement member  320   a ,  320   b  configured to engage the access member  102 , such as at the proximal and distal ends  110 ,  112  thereof, in a manner securing the attachment device  314  (and thus also the retractor body  3 ) to the wall  104 . As shown, each of the engagement members  320   a ,  320   b  can be a hook configured to hook or otherwise latch to the respective proximal and distal ends  110 ,  112  of the access member  102 . Additionally, at least one of the proximal and distal mounts  316 ,  318 , such as the engagement member  320   a ,  320   b  thereof, can be configured to move between an unlocked configuration, in which the proximal and distal mounts  316 ,  318  are longitudinally spaced from each other by a first distance L 1 , and a locked configuration in which the proximal and distal mounts are longitudinally spaced from each other by a second distance L 2  that is less than the first distance L 1 . In particular, the second distance L 2  corresponds to a distance between the proximal and distal ends  110 ,  112  of the wall  104  along the axial direction X. In this manner, the proximal and distal mounts  116 ,  118  can be configured to achieve a secure grip against the access member  102  for attaching the retractor body  3  thereto. 
     The surgical access system  100  includes an actuator  330  configured to actuate the at least one of the proximal and distal mounts  316 ,  318  from the unlocked configuration to the locked configuration. For example, the proximal mount  316  can include a mount base  322  that is coupled to the engagement member  320   a . In the illustrated embodiment, the actuator  330  extends between and connects the mount base  322  and the engagement member  320   a  together. Additionally, the actuator  330  is configured to actuate longitudinal movement of the engagement member  320   a  relative to the mount base  322  between the unlocked configuration and the locked configuration. 
     Referring now to  FIG. 4F , the actuator  330  can comprise a bias mechanism  331  for biasing one or both of the proximal and distal mounts  316 ,  318  into either the locked or unlocked configuration. In the illustrated embodiment, the bias mechanism  331  includes a spring assembly  332  that includes at least one spring  334 , such as a pair of springs  334 , that applies a bias force on the engagement member  320   a  away from the mount base  322  in a bias direction, such as the distal direction D, thereby actuating the engagement member  320   a  to the locked configuration. The spring assembly  332  can also include one or more spring guide members  336 , such as a pair of guide rods  336  or dowels, that extend centrally through the springs  334  as shown, and are configured to guide movement of the engagement member  320   a  toward and away from the mount base  322  along the longitudinal direction L. 
     The coupling mechanism  308  of the instrument  300  can be configured to move the actuator  330  in a manner causing, or at least contributing to, the actuation of one or both of the proximal and distal mounts  316 ,  318  between the locked and unlocked configurations. For example, in the illustrated embodiment, the coupling mechanism  308  can include one or more movement members, such as a pair of arms  340 , that are configured to be operatively connected to the engagement member  320   a  of the proximal mount  316  in a manner causing movement of the engagement member  320   a  relative to the mount base  322 , as described in more detail below. As shown, the arms  340  can be spaced from each other along the lateral direction A and can be translatable relative to the handle  302 , such as along an arm translation direction having at least a directional component along the forward direction FD and/or a rearward direction RD opposite the forward direction FD. The arms  340  can ride along complimentary guide formations, such as guide slots  342  defined in a body  305  of the handle  302 . The guide slots  342  and the arms  340  can have complimentary dovetail geometries, as shown. 
     Referring now to  FIG. 4G , the arms  340  can be coupled together by a yoke member  344 , which can also couple the arms  340  to a central arm  346 , that is biased along either the forward or rearward directions FD, RD. In the illustrated embodiment, the coupling mechanism  308  includes an arm bias member  348 , such as a spring, which can reside in a slot  350  defined centrally within the handle body  305 . The bias member  348  depicted is a compression spring that engages the central arm  346  so as to bias it and also arms  340  in the forward direction FD into the coupled configuration with the retractor body  3 . In the present embodiment, when in the coupled configuration, distal ends  341  of the arms  340  engage with and couple to the mount base  322 , which rigidly couples the instrument  300  to the retractor body  3 . As shown, when in the coupled configuration, the distal ends  341  of the arms  340  can extend within complimentary shaped receptacles  326  in the mount base  322  (see also  FIG. 4C ). The arms  340  are also configured to translate in the rearward direction RD to withdraw the distal end  341  of the arms  340  from the receptacles  326  of the mount base  322 , thereby moving the instrument  300  into the de-coupled configuration. In this manner, the arms  340  can be translated in the forward and rearward directions FD, RD to iterate the coupling mechanism  308  between the coupled and de-coupled configurations. Outer surfaces of the arms can include grip enhancement features  352 , such as serrations, for facilitating manual retraction of the arms  340 . As shown in  FIG. 4D , when the distal ends  341  of the arms  340  are remote from the receptacles  326  of the mount base  322 , the instrument  300  can be moved away from the attachment device  314 , which remains attached to the access member  102 . 
     Referring now to  FIG. 4H , while the coupling mechanism  308  is in the coupled configuration with the mount base  322 , the instrument  300  can also be configured to engage the actuator  330  for moving the engagement member  320   a  relative to the mount base  322 , such as to the unlocked configuration. As shown, the central arm  346  can be operationally connected to a return member  335  of the bias mechanism  331 . The return member  335  is configured to move the engagement member  320   a  toward the mount base  322  in a direction opposite the bias direction, such as the proximal direction P opposite the distal direction D, so as to move the engagement member  320   a  to the unlocked configuration. The return member  335  can be an elongated member extending proximally from the engagement member  320   a  of the proximal mount  316  and through an opening  309  at the front end  306  of the instrument  300  and into a chamber  311  defined within the handle body  305 . The opening  309  can be defined between the handle body  305  and the base member  322  of the proximal mount  316 . The return member  335  can be monolithic with the engagement member  320   a , as shown, or can alternatively be a separate member that is connected to the engagement member  320   a.    
     The instrument  300  can include a connector  337  that connects the central arm  346  to the return member  335 . A front end  337   a  of the connector  337  can be configured to reside within a recess  339  defined by the return member  335  when the coupling mechanism  308  is in the coupled configuration, as shown. The front end  337   a  of the connector  337  and the recess  339  can have complimentary geometries such that the connector  337  retains the return member  335  in the unlocked configuration (against the bias force) when the front end  337   a  resides in the recess  339 . The instrument  300  can include a second actuator, such as a button  360 , configured to iterate the engagement member  320   a  of the proximal mount  316  between the locked and unlocked configurations. The button  360  can be configured to iterate between a first or neutral button position, in which the proximal mount  316  is in the locked configuration, and a second or depressed button position, in which the proximal mount  316  is in the unlocked configuration. In particular, the button  360  can be biased into one of the neutral and depressed button positions by a button bias member, such as a spring  362 , which can reside within a button spring receptacle  364  defined within the handle body  305 . 
     The button  360  can include one or more extensions or legs  366 , such as a pair of legs  366  that straddle the central arm  346 . At least one of the button legs  366  can include a cam protrusion  367  configured to ride along a complimentary groove  369  defined in the connector  337 . The connector  337  can be pivotably coupled to the central arm  346  via a pin joint  347 , so that as the button  360  is depressed, the cam  367  and groove  369  engagement pivots the connector  337  about the pin joint  347  so that the front end  337   a  of the connector  337  pulls the return member  335  in the proximal direction P against the bias force, thereby moving the engagement member  320   a  of the proximal mount  316  to the unlocked configuration. Additionally, as the button  360  iterates to its neutral position, the cam  367  and groove  369  engagement pivots the connector  337  oppositely about the pin joint  347 , thereby allowing the bias mechanism  331  to return the engagement member  320   a  to the locked configuration. Thus, the physician can operate the button  360  to move the proximal mount  316  between the locked and unlocked configurations as needed. It should be appreciated that the front end  337   a  of the connector  337  is configured to be remote from the receptacle  339  in the rearward direction RD when the instrument  300  is in the de-coupled configuration. Thus, moving the arms  340  in the forward and rearward directions FD, RD to iterate the coupling mechanism  308  between the coupled and de-coupled configurations engages and disengages the connector  337  from the return member  335 . 
     Operation of the instrument  300  to retract soft tissue at the treatment site will now be described. The instrument  300  can be used to insert the retractor body  3  through the working channel  106  to engage and retract soft tissue. In particular, the physician can manipulate the retractor body  3  to engage and retract soft tissue via the handle  302 . Once the soft tissue is engaged, the physician can use the instrument  300  to pull the soft tissue toward the wall  104 . The design of the attachment device  314  allows the physician to elect whether to first secure the proximal or distal mount  316 ,  318  to the respective proximal or distal end  110 ,  112  of the access member  102 . The elected mount  316 ,  318  is secured to the respective end  110 ,  112  of the access member  102  by engaging the end  110 ,  112  with the hook  320   a ,  320   b  of the mount  316 ,  318 . To secure the elected mount  316 ,  318  to the respective end  110 ,  112  of the access member  102 , the physician can depress the button  360  to move the engagement member  320  of the proximal mount  316  to the unlocked configuration. It should be appreciated that, with one of the mounts  316 ,  318  secured, the physician can optionally use the secured mount  316 ,  318  as a pivot or fulcrum to bring the other of the proximal and distal mounts  316 ,  318  into alignment with the respective end  110 ,  112  of the access member  102 . With both mounts  316 ,  318  aligned with the ends  110 ,  112  of the access member  102 , the physician can then release the button  360 , thereby allowing the bias mechanism  331  to bias the proximal engagement member  320   a  away from the mount base  322  in a manner reducing the longitudinal distance between the mounts  316 ,  318  until both mounts  316 ,  318  are secured to the ends  110 ,  112  of the access member  102  in the locked configuration. 
     Referring now to  FIGS. 4I through 4K , the attachment device  314  can be configured to allow translation of the retractor body  3  along the longitudinal direction L relative to the access member  102  while attached to the wall  104 . For example, the attachment device  314  can include one or more elongate member  370 , such as a pair of rods, that extend within the working channel  106  from the proximal mount  316  to the distal mount  318 . The rods  370  are spaced from each other along the lateral direction A so that the retractor body  3  can extend between the rods  370 . One or both of the proximal and distal mounts  316 ,  318  can include guide features, such as guide shoes  372  that engage the lateral sides  20 ,  22  of the retractor body  3 . For example, the guide shoes  372  and the lateral sides  20 ,  22  of the retractor body  3  can have complimentary shapes to guide translation of the retractor body  3  along the longitudinal direction L. One or both of the proximal and distal mounts  316 ,  318  can also define a guide channel  374  having a complimentary geometry with the retractor body  3  for further guiding its translational movement  3  along the longitudinal direction L. 
     The attachment device  314  can include a retention mechanism for retaining the relative longitudinal position between the retractor body  3  and the attachment device  314 . For example, as shown in  FIG. 4H , the base member  322  can include a flexible tab or pawl  380  having a tooth  382  at a distal, free end of the pawl  380 . The tooth  382  is configured to successively engage a longitudinal series of complimentary ratchet grooves  384  defined in the outer surface  12  of the retractor body  3  as the retractor body  3  translates relative to the mount base  322 . The tooth  382  and ratchet grooves  384  can have complimentary geometries that allow the physician to manually translate the retractor body  3  longitudinally relative to the attachment device  314  as desired, yet provide sufficient resistance to retain the relative longitudinal position between the retractor body  3  and the attachment device  314  after the physician ceases manipulating the retractor body  3 . It should be appreciated that the complimentary geometries of the tooth  382  and ratchet grooves  384  can be tailored as needed to provide a desired amount of resistance to relative longitudinal movement between the attachment device  314  and the retractor body  3 . 
     Referring now to  FIG. 5A , another embodiment of the surgical access system  100  is shown that includes an instrument  400  that is releasably coupled to the retractor body  3 . As with the embodiments described above, the instrument  400  is configured to iterate between a coupled configuration, in which the instrument is coupled to the retractor body  3 , and a de-coupled configuration, in which the instrument  400  is de-coupled and removable from the retractor body  3 . For the sake of brevity, the following disclosure will focus on differences between this embodiment and the embodiment described above with reference to  FIGS. 4A through 4K . 
     In the present embodiment, the retractor body  3  carries an attachment device  414  that is operable between a locked configuration and an unlocked configuration independent of operation of the instrument  400 . As shown, the attachment device  414  includes proximal and distal mounts  416 ,  418  that can each have a hook-like geometry for engaging the proximal end distal ends  110 ,  112  of the access member  102 . An elongate actuator  430  extends proximally from the distal mount  418 , through a receptacle defined by the proximal mount  416 , and to a control member  435  that is spaced from the proximal mount  416  in the proximal direction P. The elongate actuator  430  can be a rod that can be rigidly coupled to the distal mount  418  and configured to slide the distal mount  418  along the retractor body  3  and relative to the proximal mount  416  so as to adjust the longitudinal distance between the proximal and distal mounts  416 ,  418  as needed to attach to the access member  102 . The control member  435  can be a finger tab allowing push-push operation of the elongate actuator  430  along the longitudinal direction L. 
     The instrument  400  can be used to insert the retractor body  3  through the working channel  106  to engage and retract soft tissue. As above, once the soft tissue is engaged, the physician can use the instrument  400  to pull the soft tissue toward the wall  104 , electing to secure either the proximal or distal mount  416 ,  418  to the respective proximal or distal end  110 ,  112  of the access member  102  first by hooking the end  110 ,  112  with the hook of the mount  416 ,  418 . From this position, the physician can align the other of the proximal and distal mounts  416 ,  418  with the respective end  110 ,  112  of the access member  102 , and then operate the control member  435  to reduce the longitudinal distance between the mounts  416 ,  418  until both mounts  416 ,  418  are secured to the ends  110 ,  112  of the access member  102  in the locked configuration. The proximal and distal mounts  316 ,  318  preferably each define a guide channel  474  (shown in  FIG. 5B ) having a complimentary geometry with the retractor body  3  for further guiding translational movement of the retractor body  3  along the longitudinal direction L, at least after the instrument  400  is de-coupled from the attachment device  414 . 
     Referring now to  FIG. 5B , the instrument  400  includes a coupling mechanism  408  that couples directly to the retractor body  3 . In particular, the instrument  400  has an instrument body  405  having a mounting sleeve  410  at a front end  406  thereof. The mounting sleeve  410  defines a receptacle  411  that is configured to receive a proximal portion of the retractor body  3  along the proximal direction P. Additionally, the coupling mechanism  408  includes a locking pin  422  that resides within a pin receptacle  424  defined within the instrument body  405  along a pin axis  435 . The pin axis  425  can be oriented along the transverse direction T. The pin receptacle  424  is aligned with a locking hole  426  defined within a front portion of the mounting sleeve  410 . In the present embodiment, the retractor body  3  defines a locking aperture  7  extending from the inner surface  10  to the outer surface  12  along the transverse direction T. The proximal end  4  of the retractor body  3  can be inserted along the proximal direction P within the mounting sleeve  410  until the locking aperture  7  is aligned with the locking pin  422 . Once aligned, the locking pin  422  can be advanced from a de-coupled configuration, in which the pin  422  is remote from the locking aperture  7 , to a coupled configuration, in which the locking pin  422  extends through the locking aperture  7  of the retractor body  3  and into the locking hole  426 . 
     The locking pin  422  can be iterated between the coupled and de-coupled configurations by movement of a button  460  between a first button position and a second button position along a button axis  465 . The button axis  465  can be oriented at an angle relative to the pin axis  425 . As shown, the button  460  and the pin  422  can define a complimentary camming mechanism, which can include a side pin or protrusion extending laterally from the pin  422  and into a cam groove  467  defined in a body  469  of the button  460 . In this manner, iterative motion of the button  460  along its axis  465  can drive iterative motion of the locking pin  422  along its axis  425  between the coupled and de-coupled configurations. It should be appreciated that a biasing member, such as a spring, can extend between the button  460  and the instrument body  305 , which can be operated in complimentary fashion with the camming mechanism to effectively toggle the locking pin  422  between the coupled and de-coupled configurations. 
     Referring now to  FIGS. 6A through 6F , the instrument  400  described above can be configured to employ a tensile actuator, such as a suture member  431 , for pulling the distal mount  418  toward the proximal mount  416  and moving the attachment device  414  into the locked configuration. In such embodiments, the distal mount  418  can include one or more receiving formations for receiving at least a portion of the suture member  431 . Such receiving formations can include one or more apertures  470  defined by the distal mount  418 , such as a pair of apertures  470  that are spaced apart from each other along the lateral direction A. The pair of apertures  470  can extend through a rear portion of the distal mount  418  along a direction having at least a directional component along the transverse direction T. The suture member  431  can be threaded through the apertures  470  so as to define one or more suture tails  434 , such as a pair of suture tails  434 , which can be operatively coupled to the proximal mount  416 . The proximal mount  416  can include one or more additional receiving formations  437 , such as suture channels, cleats, and the like, for receiving and securing the one or more suture tails  434  thereto. The instrument  400  can also include additional receiving formations, such as channels, cleats, and the like, for receiving and/or securing free end(s) of the one or more suture tails  434  extending from the proximal mount  416 , allowing the physician to tighten the one or more suture tails  434  relative to the instrument  400  in a secure, yet unlocked configuration. 
     As shown in  FIG. 6E , the one or more receiving formations  437  of the proximal mount  416  can be configured so that the respective suture tail  434  can lock therewith via friction. The suture member  431  can extend from a first end  439   a  thereof, through a first receiving formation  437  at the proximal mount  416 , alongside the retractor body  3  along the longitudinal direction L, through the apertures  470  in the distal mount  418 , alongside the retractor body  3  again and back toward the proximal mount  416 , through a second receiving formation  437  at the proximal mount  416 , and to a second end  439   b  of the suture member  431  opposite the first end  439   a . In this manner, the suture tail  434  adjacent the second end  439   b  can be manipulated by the physician to tension the suture member  431  to pull the distal mount  418  toward the proximal mount  416 , thereby moving the attachment device  414  into the locked configuration. Once in the locked configuration, the suture tail  434  adjacent the second end  439   b  can be secured to the second receiving formation  437 , thereby locking the attachment device  414  in the locked configuration. It should be appreciated that the first end  439   a  of the suture member  431  can be tied or otherwise configured in a knot for retaining the first end  439   a  at the first receiving formation  437 . Moreover, the second end  439   b  of the suture member  431  can optionally be coupled to a pull member, such as a rigid ring or loop, for assisting the physician in tensioning the suture member  431 . 
     In the unlocked configuration, the instrument  400  can be used to insert the retractor body  3  through the working channel  106  to engage and retract soft tissue. Once the soft tissue is engaged, the physician can use the instrument  400  to pull the soft tissue toward the wall  104 . During this process, the physician can elect to secure at least one of the proximal and distal mounts  416 ,  418  to the respective proximal and/or distal end  110 ,  112  of the access member  102 , such as by hooking the end with the hook of the mount  416 ,  418 . As above, the design of the attachment device  414  allows the physician to hook either the proximal mount  416  or the distal mount  418  to the respective end  110 ,  112  first. From this position, the physician can align the other of the proximal and distal mounts  416 ,  418  with its respective end of the access member  102 , and then apply a tensile force to the suture member  431 , such as by pulling the free suture tail  434  adjacent the second end  439   b , until the proximal and distal mounts  416 ,  418  are secured to the ends  110 ,  112  of the access member  102  in the locked configuration, as shown in  FIG. 6D . From this position, the physician can affix the free suture tail  434  to the second receiving formation  437  of the proximal mount  416  (so that both suture  434  are secured to the proximal mount  416 ), thereby maintaining the mounts  416 ,  418  in the locked configuration. The physician can also detach one or both of the ends  439   a, b  of the suture tails  434  from the receiving formations of the instrument  400 , allowing the instrument  400  to de-couple from the proximal mount  416  with the proximal and distal mounts  416 ,  418  secured in the locked configuration. 
     Similarly as described above, the proximal and distal mounts  416 ,  418  preferably each define a guide channel having a complimentary geometry with the retractor body  3  for guiding translational movement of the retractor body  3  along the longitudinal direction L relative to the mounts  416 ,  418  after the instrument  400  is de-coupled from the proximal mount  416 . For example, as shown in  FIG. 6F , one or both of the proximal and distal mounts  416 ,  418  can define a channel  474  with keystone-like channel sidewalls  475  that retains the retractor body  3  within the channel  474  while allowing longitudinal translation of the retractor body  3  relative to the mount. Additionally, the outer surface  12  of the retractor body  3  can optionally define a longitudinal channel or groove  492  configured to receive the suture member  431 . It should also be appreciated that the instrument  400  of the present embodiment can employ the same or a similar coupling mechanism as the coupling mechanism  408  described above with reference to  FIG. 5B  for selectively coupling directly to and de-coupling from the retractor body  3 . In such embodiments, the proximal mount  416  can be rigidly affixed to the mounting sleeve  410  of the coupling mechanism. It should further be appreciated that in additional embodiments the instrument  400  described above with reference to  FIGS. 6A through 6F  can be configured to employ a tensile actuator that is alternatively an elastic member, such as an elastic band, by way of a non-limiting example. 
     Referring now to  FIGS. 7A through 7C , the surgical access system  100  can include an attachment device  714  having proximal and distal mounts  716 ,  718  and employing a retention mechanism, such as a ratchet or ratchet-like mechanism, for securing the mounts  716 ,  718  in the locked configuration to the access member  102 . Similar to the embodiments described above with reference to  FIGS. 4A through 6D , one or both of the proximal and distal mounts  716 ,  718  of the present embodiment are configured to iterate between unlocked and locked configurations. Additionally, as above, the mounts  716 ,  718  include engagement members  720   a ,  720   b , such as hooks, that are configured to hook, latch, or otherwise secure to the respective proximal and distal ends  110 ,  112  of the access member  102  when in the locked configuration. For the sake of brevity, the following disclosure will focus on differences between the present embodiment and the embodiments described above with reference to  FIGS. 4A through 6D . 
     As shown in  FIG. 7A , each of the proximal and distal mounts  716 ,  718  can include an elongate body portion  719  that is elongated along the longitudinal direction L and conformally shaped with the outer surface  12  of the retractor body  3  for guiding translational movement of the retractor body  3  relative to the mounts  716 ,  718 . The elongate body portions  719   a ,  719   b  are configured to extend within the working channel  106  and reside between the retractor body  3  and the inner wall surface  116  of the access member  102 . The proximal mount  716  can also include an elongate handle portion  702  that extends from the elongate body portion  719   a  and is configured to allow a physician to manipulate the retractor body  3  for engaging soft tissue at the treatment site. For example, the elongate handle portion  702  can be configured for manipulation by the physician&#39;s index finger. As shown in  FIG. 7B , the handle portion  702  can have a circular shape in other embodiments. In yet other embodiments, the handle portion  702  can be configured to deflect between at least one of the elongate ( FIG. 7A ) and circular ( FIG. 7B ) configurations to the other configuration. 
     The attachment device  714  includes an elongate actuator  730  that extends proximally from the distal mount  718 , through and/or alongside the proximal mount  716 , and to a control member  735  that is spaced from the proximal mount  716  in the proximal direction P. As shown, the elongate actuator  430  can be a pair of rods  731  that can be rigidly coupled to the distal mount  718  and configured to translate the distal mount  718  along the retractor body  3  and relative to the proximal mount  716  to iterate the mounts  716 ,  718  between the locked and unlocked configurations, similarly as described above with reference to  FIG. 5A . As above, the control member  735  can be a finger tab allowing push-push operation of the actuator rods  731  along the longitudinal direction L. For example, the control member  735  can be configured for manipulation by the physician&#39;s thumb, while the handle portion  702  is configured for manipulation by the physician&#39;s index finger. As shown in  FIG. 7C , the actuator rods  731  can extend through guide channels  737  defined in the outer surface  12  of the retractor body  3 . The actuation rods  731  can also extend through complimentary guide channels  739  defined by the elongate body portion  719   a  of the proximal mount  716 . In this manner, the actuator rods  731  can translate the distal mount  716  relative to the proximal mount  716 . 
     Referring now to  FIGS. 7D and 7E , the retractor body  3  and the proximal and distal mounts  716 ,  718  can include guide features for guiding translational movement of the retractor body  3  relative to the mounts  716 ,  718  and vice versa, such as for translating the retractor body  3  relative to the access member  102 . For example, the retractor body  3  can define a slot  740  elongate along the longitudinal direction L. The mounts  716 ,  718  can each include slide members  742  that extend from the respective elongate body portion  719   a ,  719   b  and within the slot  740  and are configured to ride longitudinally along the slot. Within the slot  740 , the retractor body  3  can define side walls  744  that are canted inwardly toward each other, and the slide members  742  can have a flared geometry that is complimentary with the canted geometry of the side walls  744  in dovetail fashion. In this manner, the sidewalls  744  can retain the slide members  742  within the slot  740 , thus also retaining the proximal and distal mounts  716 ,  718  in engagement with the outer surface  12  of the retractor body  3 . 
     Referring now to  FIGS. 7F through 7H , the retention mechanism for selectively retaining the relative longitudinal position between the proximal and distal mounts  716 ,  718  will now be described. The retractor body  3  can define, for example, a series of ratchet grooves  750  that are arranged longitudinally alongside the slot  740  and are configured to engage at least one complimentary ratchet tooth  752  of at least one of the proximal and distal mounts  716 ,  718 . The ratchet grooves  750  can be defined in the outer surface  12  of the retractor body  3 , and can also be at least partially defined by the sidewalls  744  within the slot  740 . 
     As shown in  FIGS. 7G and 7H , the ratchet tooth  752  can extend from a flexible tab  754 , which can also be referred to as a “pawl”, and which can be defined by the elongate body portion  719   a  of the proximal mount  716 . The ratchet tooth  752  is configured to selectively engage at least one and up to each of the ratchet grooves  750  in succession as the proximal mount  716  translates longitudinally relative to the retractor body  3 . The ratchet tooth  752  can be located at a first end  756  of the pawl  754  opposite a second end  758  of the pawl  754 . The second end  758  can include the hook  320   a  of the proximal mount  716 . The pawl  754  can reside within a recess of cutout  760  defined by the elongate body portion  719   a . The pawl  754  can be connected to a remainder of the elongate body portion  719   a  by a pair of arms  762  opposite each other along the lateral direction A. The pair of arms  762  can provide the pawl  752  with flexibility for rotation along a plane defined by the longitudinal and transverse directions T. In this manner, the pawl  754  can be configured to iterate between a neutral or engaged configuration (as shown in  FIG. 7G ), in which the tooth  752  resides within one of the ratchet grooves  750  so as to retain a relative longitudinal position between the proximal mount  716  and the retractor body  3 , and a flexed or disengaged configuration, in which the tooth  752  is remote from each of the ratchet grooves  750 . 
     The tooth  752  and ratchet grooves  750  can have complimentary geometries that provide substantially equivalent resistance to proximal or distal movement of the proximal mount  716  relative to the retractor body  3 . It should be appreciated that the complimentary geometries of the tooth  752  and ratchet grooves  750  can be tailored as needed to provide a desired amount of resistance to relative longitudinal movement between the proximal mount  716  and the retractor body  3 . In other embodiments, the tooth  752  and ratchet grooves  750  can have complimentary geometries that prevent proximal movement of the proximal mount  716  relative to the retractor body  3  in the engaged configuration. In such embodiments, the pawl  754  can optionally include a disengagement feature for manually rotating the pawl  754  to the disengaged configuration. It should be appreciated that the retention mechanism of the foregoing embodiments can provide audible and/or tactile feedback regarding relative longitudinal movement between the proximal mount  716  and the retractor body  3  as the tooth  752  successively “clicks” into and out of the ratchet grooves  750 . It should be appreciated that in other embodiments, controlled movement of the proximal and distal mounts  716 ,  718  relative to one another can employed in a friction-based retention mechanism. 
     Operation of the retractor  2  of the present embodiment will now be described. The handle portion  702  can be used to insert the retractor body  3  through the working channel  106  to engage and retract soft tissue. Once the soft tissue is engaged, the physician can use the handle portion  702  to pull the soft tissue toward the wall  104 , electing to secure either the proximal or distal mount  716 ,  718  to the respective proximal or distal end  110 ,  112  of the access member  102  first by hooking the end  110 ,  112  with the hook of the mount  716 ,  718 . From this position, the physician can align the other of the proximal and distal mounts  716 ,  718  with the respective end  110 ,  112  of the access member  102 , and then operate the control member  735  to reduce the longitudinal distance between the mounts  716 ,  718 , thereby causing the ratchet tooth  752  to sequentially engage the ratchet grooves  750 , until both mounts  716 ,  718  are secured to the ends  110 ,  112  of the access member  102  in the locked configuration. 
     It should be appreciated that each of the embodiments described above with reference to  FIGS. 4A through 7H , in which the respective attachment devices  314 ,  414 ,  714  attach to the ends  110 ,  112  of the access member  102 , allow multiple retractors  2  to be attached concurrently to various select circumferential locations of the access member  102 . 
     Referring now to  FIGS. 8A through 8C , the surgical access system  100  can include a suction attachment device  814  configured to selectively attach the retractor body  3  to a circumferential portion of the inner wall  116  of the access member  102 . For example, the retractor body  3  can define an internal chamber  816  in fluid communication with a plurality of vacuum ports  818  defined in the outer surface  12  of the retractor body  3 . The internal chamber  816  is also in fluid communication with a proximal port  820  that is connectable to a tube  822  that is in turn connectable to a vacuum source  824 , such as a vacuum pump. A plurality of ring seals  826  are located in the vacuum ports  818  and are configured to provide sealing engagement with the inner wall surface  116  when the ring seals  826  are brought into contact with the inner wall surface  116  and the vacuum source  824  supplies vacuum pressure to the internal chamber  816  and thus also to the vacuum ports  818 . The suction attachment device  814  can be configured to provide a tailored sufficient suction force allowing the retractor body  3  to translate at least longitudinally relative to the access member  102  while the retractor body  3  remains attached to the access member  102  via the suction attachment device  814 . It should be appreciated that the present embodiment allows multiple retractors  2  to be attached via suction concurrently to various select circumferential locations of the inner wall surface  116 . 
     Referring now to  FIGS. 9A through 9C , the surgical access system  100  can include an attachment device  914  that employs mating engagement between protrusions  920  and openings  922  for selectively attaching the retractor body  3  to a circumferential portion of the access member  102 . For example, at least one of the inner wall surface  116  and the retractor body  3  can define one or more openings  922 , and the other of the inner wall surface  116  and the retractor body  3  can comprise one or more protrusions  920  that are complimentary with the one or more openings  922 . Stated differently, the one or more protrusions  920  are configured for insertion within the one or more openings  922  so as to couple the retractor body  3  to the access member  102 . 
     As shown in  FIG. 9A , the wall  104  of the access member  102  can define an array  924  of openings  922  and the retractor  2  can include a series of protrusions  920  for engagement within selective ones of the openings  922 . The protrusions  920  can be defined by, and monolithic with, the retractor body  3 , or can be carried by an insert connectible with the retractor body  3 . The protrusions  920  extend outwardly from the outer surface  12  of the retractor body  3  and are aligned with each other along the longitudinal direction L. The openings  922  can each extend outwardly into the wall from the inner surface  116  thereof. The array  924  can include one or more columns  926  of openings  922  and one or more rows  928  of openings  922 . In each column  926 , the openings can be aligned with each other along the longitudinal direction L. Thus, each column  926  can be characterized as defining a longitudinally aligned subset of the openings  922  in the array  924 . The columns  926  are circumferentially spaced from each other along the wall  104 . In each row  928 , the openings  922  can be aligned along the lateral direction A. Thus, each row  928  can be characterized as defining a laterally aligned subset of the openings  922  in the array  924 . The rows  928  are spaced from each other along the axial direction X of the access member  2  (and also along the longitudinal direction L of the retractor  2  when the retractor  2  is attached to the access member  102 ). In the embodiment illustrated in  FIG. 9A , the protrusions  920  are configured for insertion within any one of columns  926  to selectively attach the retractor body  3  to a circumferential portion of the access member  102 . It should be appreciated that the retractor  2  can have fewer protrusions  920  than the number of openings  922  in a column  926 . In such embodiments, the retractor  2  can also be selectively attached to the access member  102  at a select depth (i.e., select longitudinal location). 
     The protrusions  920  can optionally define a stem  930  extending from the retractor  2  and a head  932  located at an outer end of the stem  930  and being wider than the stem  930 . As shown in  FIG. 9B , the openings  922  can extend radially through the wall  104  from the inner wall surface  116  to the outer wall surface  114 . In such embodiments, the protrusions  920  can be configured such that the stems  930  extend through the openings  922  and at least portions of the heads  932  are located radially outward of the outer wall surface  114  when the retractor body  3  is attached to the access member  102 . As shown, the stems  930  can be sufficiently long so that the entire head  932  is located radially outward of the wall  102 . In such embodiments, at least a portion of the head  932  can overlap at least a portion of the wall  104  along the axial direction X of the access member  102  (and thus also along the longitudinal direction L of the retractor  2 ) when the retractor  2  is attached to the access member wall  104 . Thus, the protrusions  920  and the openings  922  can be cooperatively configured to resist inadvertent detachment of the retractor  2  from the access member wall  104  along the transverse direction T. 
     In other embodiments, as shown in  FIG. 9C , the openings  922  can extend from the inner wall surface  116  and terminate at a location radially inward of the outer wall surface  114 . In such embodiments, the opening  922  can include an axial receptacle  934  configured to receive a portion of the mating head  932 , such that at least a portion of the head  932  overlaps at least a portion of the wall  104  along the axial and longitudinal directions X, L, respectively, as above. It should be appreciated that other complimentary protrusion  920  and opening  922  geometries for providing sturdy, selective attachment of the retractor  2  to the access member wall  104  are within the scope of the present disclosure. It should also be appreciated that in other embodiments the protrusions  920  can extend inwardly from the inner wall surface  116  of the access member  102  and the openings  922  can be defined in the retractor body  3 . 
     In a surgical procedure using the surgical access system  100  of the present embodiment, the physician can insert the retractor body  3  through the working channel  106  to engage and retract soft tissue. Once the soft tissue is engaged, the physician can manipulate the proximal end  4  of the retractor  2  to pull the soft tissue toward the wall  104 . In particular, the physician can identify the column  926  of openings  922  in the inner wall surface  116  that is in substantial radial alignment with the desired direction of retraction for coupling with the protrusions  920  of the retractor  2 . The physician can then insert the protrusions  920  of the retractor  2  within the select openings  922  of the column  926  at the desired longitudinal position of the retractor  2  relative to the access member  102 , thereby affixing the retractor  2  to the inner wall surface  116  at the select circumferential and longitudinal positions of the inner wall surface  116 . It should be appreciated that multiple retractors  2  can be affixed to the inner wall surface  116  in like manner for retracting soft tissue as needed. 
     Referring now to  FIGS. 9D and 9E , an additional embodiment is shown in which one or more protrusions  920  extend proximally from a proximal surface  111  of the access member  102 . The proximal surface  111  can define the proximal end  110  of the access member  102 . In such embodiments, the one or more protrusions  920  can include a plurality of protrusions  920  spaced circumferentially from one another along the proximal surface  111 . The proximal surface  111  can be defined by a flange  113  at the proximal end  110  of the access member  102 . In the present embodiment, the retractor body  3  defines one or more openings  922  extending therethrough from the inner surface  10  to the outer surface  12 . Particularly, the retractor body  3  of the present embodiment can be either pre-bent or bendable such that a first or proximal portion  3   a  of the retractor body  3  is angularly offset relative to a second or distal portion  3   b  of the retractor body  3 , as described above with reference to  FIG. 1C . The proximal portion  3   a  defines at least one opening  922  that extends along the axial direction X and can thus be mated with a select one of the protrusions  920  for attaching the retractor body  3  to the associated select circumferential portion of the access member  102 . As shown, the proximal and distal portions  3   a ,  3   b  of the retractor body  3  can be angularly offset from each other in the L-T plane, such that the distal portion  3   b  extends through the working channel  106  substantially along the axial direction X while the proximal portion  3   a  is elongate along the radial direction R (or at least along a direction having a directional component along the radial direction R). 
     In embodiments where the retractor body  3  is pre-bent, the proximal portion  3   a  defines a single opening  922 . In embodiments where the retractor body  3  is bendable, the retractor body  3  can define a plurality of openings  922  spaced in series along the longitudinal direction L, allowing the physician to bend the retractor body  3  at a select longitudinal location to define the respective lengths of the proximal and distal portions  3   a ,  3   b , thereby defining the insertion depth of the distal portion  3   b  when attached to the retractor body  3 . It should be appreciated that, as above, the protrusions  920  can have a stem  930  and a head  932 , and can be cooperatively configured with the opening  922  so that the head  932  can overlap at least a portion of the retractor body  3  along the radial direction R when the retractor body  3  is attached to the access member  102 . Such overlap can increase the sturdiness of attachment between the retractor body  3  and the access member  102 . 
     During use of the embodiment shown in  FIGS. 9D and 9E , the physician can identify the protrusion  920  on the proximal surface  111  in substantial radial alignment with the desired direction of retraction for coupling with the opening  922  of the retractor  2 . The physician can insert the retractor body  3  through the working channel  106  and engage and retract soft tissue in the radial direction R, bringing the distal portion  3   b  of the retractor body  3  toward the inner wall surface. In embodiments where the retractor body  3  is pre-bent, the foregoing step also brings the opening  922  in the bent proximal portion  3   a  into alignment with the selected protrusion  920 . In embodiments where the retractor body  3  is bendable, the physician can bend the retractor body  3  at the select longitudinal location to provide the distal portion  3   b  with the desired axial depth relative to the access member  102 . In either embodiment, with the distal portion  3   b  engaged with soft tissue and moved toward the select circumferential portion of the inner wall surface  116 , the physician can move the proximal portion  3   a  so that the opening  922  receives the select protrusion  920 , thereby attaching the retractor body  3  to the access member  102  as desired. It should be appreciated that multiple retractors  2  can be affixed to the access member  102  in like manner for retracting soft tissue as needed. 
     Referring now to  FIGS. 10A and 10B , an attachment device  1014  for the surgical access system  100  can include a flexible wire  1050  that is configured to be inserted into the working channel  106  of the access member  102  in a first or insertion configuration and then deform into a second or deployed configuration for pushing the retractor body  3  against the inner wall surface  116  and securing it thereto. For example, the wire  1050  can be pre-formed into a neutral shape, such as one or more coils, for example, and can then be loaded into an introducer instrument  1070  (also referred to herein as the introducer  1070 ) that maintains the wire  1050  in the insertion configuration. The introducer  1070 , or at least an end portion thereof, can be inserted within the working channel  106 , and the wire  1050  can be deployed (i.e., expelled) from the introducer  1070  and into the working channel  106 , wherein the wire  1050  elastically deforms from its insertion configuration to the deployed configuration. This deformation can cause the wire  1050  to form one or more coils that extend circumferentially about the inner wall surface  116  and exert a radially outward spring force F that pushes the retractor body  3  securely against the inner wall surface  116  as the wire  1050  attempts to return to its neutral configuration. In other embodiments, the wire  1050  can be configured as a helical spring when in the neutral configuration, and can be further twisted helically so as to reduce its spring diameter when in the insertion configuration. Once inserted to the desired location within the working channel  106 , the wire  1050  can be released so as to expand within the working channel  106  to the deployed configuration. It should be appreciated that the wire  1050  can be constructed of a shape-memory material that is also bio-compatible, such as nitinol, by way of a non-limiting example. 
     The wire  1050  can have a substantially purely coiled shape in the deployed configuration. In other embodiments, as shown in  FIGS. 10C and 10D , the wire  1050  can have an alternate shape in the deployed configuration. For example, the wire  1050  can be configured such that when it is in the deployed configuration, the wire  1050  can define a longitudinal portion  1052  configured to engage along the length of the retractor body  3  and one or more arm portions  1054  configured to engage the inner wall surface  116  of the access member  102 . It should be appreciated that other deployed configurations are also within the scope of the present disclosure. 
     The retractor bodies  3  of any of the preceding embodiments can be constructed of bio-compatible materials including metals, polymers, composite materials, or any combination of the foregoing, by way of non-limiting examples. 
     It should be appreciated that the retractors  2  and attachment devices  14 ,  314 ,  414 ,  714 ,  814 ,  914  described above allow selective placement of the retractor  2  relative to the access member  102 , including circumferentially and longitudinally, and thus likewise relative to patient anatomy for fine control of soft tissue retraction. Such fine control of soft tissue retraction is particularly beneficial because, among other things, it reduces the need for resection (removal) of soft tissue at the treatment site. 
     Referring now to  FIGS. 11A and 11B , the retractor members  2  of any of the embodiments described above can include at least one sensor  1102  that is electrically conductive and located at or adjacent the distal end  12  of the retractor  2 . The sensor  1102  can be employed for neuromonitoring (e.g., for detecting the presence, proximity, health, and/or other attributes of nerve tissue) at the treatment site, such as to navigate the retractor  2  around (e.g., avoid) nerve tissue, to safely retract nerve tissue with the retractor  2 , and/or to assess the health of nerve tissue at the treatment site, as more fully described in the &#39;253 Reference. It should be appreciated that the sensor  1102  can include a single sensor or a plurality of sensors. The sensor  1102  can be in electrical communication with an electric lead  1104  that is located at or adjacent the proximal end  10  of the retractor  2  and is configured for transmitting electrical information obtained by the sensor to a control unit  1106 , which can employ a processor  1108  for interpreting the electrical information. 
     As shown in  FIG. 11A , in one such embodiment that employs a sensor  1102 , the retractor  2  can include a retractor body  3  that is constructed of an electrically conductive material. The retractor  2  can also include an electrically insulative sheath  1110  disposed over a major portion  3   i  of the retractor body  3 . The sheath  1110  can be configured to provide an exposed portion  3   j  of the retractor body  3  that defines the sensor  1102 . The exposed portion  3   j  can extend from the sheath  1110  to the distal end  12 . The sheath  1110  can also be configured to provide another exposed portion  3   k  of the retractor body  3  that defines the electric lead  1104 , which can extend from the sheath  1110  to the proximal end  10 . It should be appreciated that, as an alternative to the sheath  1110 , the retractor body  3  can be coated with a layer of insulative material, which layer can be formed or finished so as to provide an exposed portion of the retractor body  3  at or adjacent the distal end  12 , which exposed portion can define or carry the sensor  1102 . The coating can also be configured to provide an additional exposed portion of the retractor body  3 , such as at or adjacent the proximal end  12 , for providing the electric lead  1104 . 
     As shown in  FIG. 11B , in another embodiment that employs a sensor  1102 , retractor  2  can include a retractor body  3  that is constructed of an electrically insulative material, and the sensor  1102  can be disposed over or embedded within the retractor body  3  at or adjacent the distal end  12  thereof. The electric lead  1104  can also be disposed over or embedded within the retractor body  3 , such as at the proximal end  10  thereof. The retractor  2  can include an electrical transmission element, such as a wire or trace extending along or through the retractor body  3 , from the sensor  1102  to the electric lead  1104 . 
     The insulate materials described above can include parylene, silicone rubbers, fluoropolymers, and elastomers, by way of non-limiting examples. It should be appreciated that in other embodiments employing a sensor  1102 , the sensor  1102  can be in wireless communication with the control unit  1106  and/or processor  1108 . 
     Referring now to  FIGS. 12A through 12E , in yet other embodiments, an attachment device  1214  for the surgical access system  100  can include a tether  1211  extending from the proximal end  4  of the retractor body  3 . As shown in  FIG. 12A , the retractor body  3  can be carried by an instrument  1200 , which can include a distal elongate portion  1205  that extends along the longitudinal direction L and carries the retractor body  3 , such as by bracketing the lateral sides of the retractor body  3 . The distal elongate portion  1205  is configured for insertion within the access member  102  to engaging soft tissue with the retractor body  3 . The retractor body  3  can define a distal mount  1218 , such as a hook, which can extend from the outer surface  12  of the retractor body  3 . Additionally, the distal mount  1218  can be configured to engage the distal end  112  of the access member  102 . Additionally or alternatively, the distal mount  1218  can be configured to selectively engage any of a plurality of slots  1220  defined in the wall  104  of the access member  102 , as shown in  FIGS. 12D and 12E . 
     The tether  1211  can be a wire, suture member, string, or cord, by way of non-limiting examples. Alternatively, as shown in  FIG. 12C , the tether  1211  can be a band, such as an elastic band. The tether  1211  can be configured to secure to one or more receiving formations  1215  defined by or carried by the access member  102 . The receiving formations  1215  can be receptacles, channels, cleats, and the like, which can be defined on or carried by an exterior of the access member  102 . Alternatively, as shown in  FIG. 12D , the receiving formations  1215  can optionally be defined on or carried by an access member holder  1260  connected to the access member  102 . As shown in  FIG. 12E , alternatively or in addition to the receiving formations  1215 , the tether  1211  can be affixed to the proximal end  110  of the access member  102  with a fastener, such as a spring clip  1270 , for example. 
     Although the disclosure has been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, features of the various embodiments described herein can be incorporated into one or more and up to all of the other embodiments described herein. Moreover, the scope of the present disclosure is not intended to be limited to the particular embodiments described in the specification. As one of ordinary skill in the art will readily appreciate from that processes, machines, manufacture, composition of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present disclosure.