Abstract:
A torque-transmitting, variably-flexible device, comprising a hollow body having a proximal end, a distal end and a given length, a torque-transmitting element that extends substantially entirely over the given length of the hollow body, a steering element that steers the distal end of the hollow body, the steering element being comprised of steering tendons disposed within the hollow body, and stiffening tendons disposed within the hollow body to selectively maintain the hollow body in a relatively stiff condition, wherein the stiffening tendons are unassociated with the steering element of the device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is:
   a continuation-in-part of U.S. patent application Ser. Nos.:   
 
         [0003]    Ser. No. 11/367,607, filed on Mar. 2, 2006, now U.S. Pat. No. 8,092,374; 
         [0004]    Ser. No. 11/502,322, filed on Aug. 10, 2006, now U.S. Pat. No. 7,988,621; 
         [0005]    Ser. No. 11/804,843, filed on May 21, 2007, now U.S. Pat. No. 8,556,804; 
         [0006]    Ser. No. 11/823,247, filed on Jun. 27, 2007; 
         [0007]    Ser. No. 12/432,351, filed on Apr. 29, 2009, now U.S. Pat. No. 7,914,445; 
         [0008]    Ser. No. 13/006,745, filed on Jan. 14, 2011, now U.S. Pat. No.8,292,802; 
         [0009]    Ser. No. 13/006,760, filed on Jan. 14, 2011, now U.S. Pat. No. 8,298,137; 
         [0010]    Ser. No. 13/311,145, filed on Dec. 5, 2011, now U.S. Pat. No. 8,696,639; 
         [0011]    Ser. No. 13/622,240, filed on Sep. 18, 2012, now U.S. Pat. No. 8,708,894; and
   is a divisional of U.S. patent application Ser. No. 14/021,266, filed on Sep. 9, 2013,   the entire disclosures of which are all hereby incorporated herein by reference in their entireties.   
 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0014]    Not Applicable. 
     
    
     FIELD OF INVENTION 
       [0015]    The invention relates to a variably flexible insertion device and to a method for variably flexing an insertion device. The invention also relates to a method for transmitting torque and variably flexing a corrugated insertion device. The invention further relates to a torque-transmitting, variably-flexible, locking insertion device. The insertion device may be used to insert an instrument, in particular a scope, such as an endoscope or a colonoscope, into a patient. 
       BACKGROUND OF THE INVENTION 
       [0016]    Insertion devices for surgical instruments are known in the art. Prior art insertion devices of this general type have been quite complicated, cumbersome and difficult to use. Such devices have a relatively large diameter, a limited maximum length, a limited transmission of torque and present obstacles to insertion of instruments. For example, a disadvantage of such variably flexing insertion devices is that the device twists when applying torque to the proximal end and therefore the torque is not transmitted along the device toward the distal end. This makes it difficult or impossible to impart a circumferential movement along the device when needed to traverse the body. 
         [0017]    In addition, prior art devices of this general type cannot be connected to an instrument, such as an endoscope or a colonoscope, in such a manner as to be reliable and sufficiently torque-transmitting, while at the same time being easily releasable therefrom and variably flexible. The operator of the device must have the ability to manipulate the instrument when necessary with the insertion device and yet free the instrument easily when necessary. 
       SUMMARY OF THE INVENTION 
       [0018]    It is accordingly an object of the invention to provide a torque-transmitting, variably-flexible device, which comprises a hollow body having a proximal end, distal end and a given length, a torque-transmitting element that extends substantially entirely over the given length of the hollow body, a steering element that steers the distal end of the hollow body, the steering element being comprised of steering tendons disposed within the hollow body, and stiffening tendons disposed within the hollow body to selectively maintain the hollow body in a relatively stiff condition, wherein the stiffening tendons are unassociated with the steering element of the device. 
         [0019]    Other features that are considered as characteristic for the invention are set forth in the appended claims. 
         [0020]    Although the invention is illustrated and described herein as embodied in a torque-transmitting, variably flexible insertion device and a method for variably flexing an insertion device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
         [0021]    The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    Advantages of embodiments of the present invention will be apparent from the following detailed description of the preferred embodiments thereof, which description should be considered in conjunction with the accompanying drawings in which: 
           [0023]      FIG. 1  is a diagrammatic, side-elevational view of an exemplary embodiment of a variably flexible insertion device according to the invention; 
           [0024]      FIG. 2  is a view similar to  FIG. 1  showing details of the interior of the insertion device of the embodiment of  FIG. 1 ; 
           [0025]      FIG. 3  is an enlarged, fragmentary, perspective view showing inner and outer handles, locking pads and tendons of the insertion device of the embodiment of  FIG. 1 ; 
           [0026]      FIG. 4  is a view similar to  FIG. 3 , showing the inner and outer handles and a friction surface and grooves for the tendons; 
           [0027]      FIG. 5  is a perspective view of a portion of the insertion device of the embodiment of  FIG. 1 , showing details of the inner and outer handles; 
           [0028]      FIG. 6  is an enlarged, fragmentary, side-elevational view of a nose tip and tendons of the insertion device of the embodiment in  FIG. 1 ; 
           [0029]      FIG. 7  is a fragmentary, perspective view of the nose tip showing details of the tendons and vertebrae; 
           [0030]      FIG. 8  is a fragmentary, longitudinal-sectional view of the nose tip and vertebrae; 
           [0031]      FIG. 9  is an enlarged, fragmentary, perspective view of the tendons over a friction zone; 
           [0032]      FIG. 10  is a fragmentary, perspective view illustrating the tendons in transition and locking; 
           [0033]      FIG. 11  is a fragmentary, perspective view showing the locking pads for the tendons; 
           [0034]      FIG. 12  is a fragmentary, longitudinal-sectional view of the handle of the embodiment of  FIG. 1 ; 
           [0035]      FIG. 13  is a fragmentary, longitudinal-sectional view of a handle locking area; 
           [0036]      FIG. 14  is a cross-sectional view taken along a line XIV-XIV of  FIG. 3 , through the handle assembly during transition; 
           [0037]      FIG. 15  is a cross-sectional view taken along a line XV-XV of  FIG. 10 , through the vertebrae with the tendons; 
           [0038]      FIG. 16  is a cross-sectional view taken along a line XVI-XVI of  FIG. 3 , through the vertebrae with the tendons; 
           [0039]      FIG. 17  is a fragmentary, side-elevational view of the device of the embodiment of  FIG. 1  in a flexed condition, showing the nose tip, the vertebrae and the effect of bending on the tendons; 
           [0040]      FIG. 18  is a view similar to  FIG. 11  showing a slit hollow body with a zipper closure; 
           [0041]      FIG. 19  is a perspective view of a coil used with the device of  FIG. 18 ; 
           [0042]      FIG. 20  is a diagrammatic, side-elevational view of a torque-transmitting, variably-flexible, corrugated insertion device according to another exemplary embodiment of the invention, in which an outer jacket has been partly removed to show corrugations, tendons and vertebrae and in which the device has been steered to the right; 
           [0043]      FIG. 21  is a side-elevational view of the insertion device of the embodiment of  FIG. 20  in which corrugations are illustrated at the distal tip as in  FIG. 20 , and in which an outer covering of a handle has been removed; 
           [0044]      FIG. 22  is a perspective view showing stiffener zones of the insertion device of the embodiment of  FIG. 20  and illustrating corrugations at the distal tip; 
           [0045]      FIGS. 23 and 24  are fragmentary, side-elevational views of a steering assembly of the insertion device of the embodiment of  FIG. 20  with corrugations illustrated in different locations; 
           [0046]      FIG. 25  is an enlarged, fragmentary, longitudinal-sectional view of a distal tip region of the insertion device of the embodiment of  FIG. 20 ; 
           [0047]      FIG. 26  is a view of the insertion device similar to  FIG. 25 , in which tendons have been shown; 
           [0048]      FIG. 27  is an elevational view of a corrugated tube of the insertion device of the embodiment of  FIG. 20  in which straight and stepped cuffs have been shown; 
           [0049]      FIG. 28  is a fragmentary, longitudinal-sectional view of the insertion device of the embodiment of  FIG. 20  in which an inner liner, an inner handle and a corrugation cuff have been shown; 
           [0050]      FIG. 29  is a fragmentary, perspective view of the distal tip region of the insertion device of the embodiment of  FIG. 20 ; 
           [0051]      FIG. 30  is a fragmentary, perspective view of the distal tip region of the insertion device of the embodiment of  FIG. 20  in which the outer jacket has been removed to show the tendons, the vertebrae and the corrugations; 
           [0052]      FIG. 31  is a view of the insertion device similar to  FIG. 30 , in which the tip has been removed; 
           [0053]      FIG. 31A  is an enlarged, perspective view of a U-shaped tendon; 
           [0054]      FIG. 32  is a view of the insertion device similar to  FIGS. 30 and 31 , in which the tip and a termination bushing have been removed; 
           [0055]      FIG. 33  is a cross-sectional view of the insertion device, which is taken along a line IVX-IVX of  FIG. 30 , in the direction of the arrows; 
           [0056]      FIG. 34  is a further enlarged, perspective view of a snap vertebra of the insertion device; 
           [0057]      FIG. 35  is a perspective view of a continuous vertebra of the insertion device; 
           [0058]      FIG. 36  is a diagrammatic, side-elevational view of a steerable, variably-flexible insertion device according to another exemplary embodiment of the invention, which has been steered to the right; 
           [0059]      FIG. 37  is a view similar to  FIG. 36 , of the insertion device steered to the left; 
           [0060]      FIG. 38  is a perspective view of the insertion device of  FIGS. 36 and 37 ; 
           [0061]      FIG. 39  is a fragmentary, side-elevational view of a steering assembly of the insertion device of the embodiment of  FIG. 36 ; 
           [0062]      FIG. 40  is a perspective view of a stiffness zone assembly of the insertion device of the embodiment of  FIG. 36 ; 
           [0063]      FIG. 41  is a longitudinal-sectional view of a sliding tire valve and side tube assembly of the insertion device of the embodiment of  FIG. 36 ; 
           [0064]      FIG. 42  is an elevational view of an ergonomically constructed valve handle to be used with the insertion device of the embodiment of  FIG. 36 ; 
           [0065]      FIG. 43  is a longitudinal-sectional view of the handle of  FIG. 42 ; 
           [0066]      FIG. 44  is an elevational view of a torque braid of the insertion device of the embodiment of  FIG. 36 ; 
           [0067]      FIG. 45  is an enlarged, fragmentary, perspective view of the torque braid between an outer jacket and an inner sleeve covering a coil of the insertion device of the embodiment of  FIG. 36 ; 
           [0068]      FIG. 46  is a fragmentary, perspective view showing tendons intermittently woven through the torque braid; and 
           [0069]      FIGS. 47 ,  48 ,  49 , and  50  are cross-sectional views of the insertion device, which are taken along a line XII-XV of  FIG. 37 , in the direction of the arrows, but with the torque braid in various locations; 
           [0070]      FIG. 51  is a diagrammatic, perspective view of a torque-transmitting, variably-flexible, locking insertion device according to another exemplary embodiment of the invention; 
           [0071]      FIG. 52  is a perspective view similar to  FIG. 51 , showing a working length of the insertion device; 
           [0072]      FIG. 53  is an enlarged, perspective view of the insertion device of the embodiment of  FIG. 51 , showing details of a proximal end; 
           [0073]      FIG. 54  is a fragmentary, further enlarged, top-plan view of the proximal end of the insertion device of the embodiment of  FIG. 51 ; 
           [0074]      FIG. 55  is an even further enlarged, fragmentary, side-elevational view of the proximal end of the insertion device of the embodiment of  FIG. 51 ; 
           [0075]      FIG. 56  is a perspective view of the insertion device of the embodiment of  FIG. 51  with an outer jacket removed; 
           [0076]      FIG. 57  is a fragmentary, enlarged, side-elevational view of the proximal end and part of the working length of the insertion device with the outer jacket removed; 
           [0077]      FIG. 58  is a view similar to  FIG. 56 , of the insertion device with a lock in an actuated condition; 
           [0078]      FIGS. 59A and 59B  are even further enlarged, fragmentary, elevational views of a distal end of the insertion device in which a locking ring is respectively shown and omitted for clarity and in which the outer jacket has been removed; 
           [0079]      FIGS. 60A and 60B  are fragmentary, perspective views of the distal end of the insertion device in which the locking ring is respectively shown and omitted for clarity and in which the outer jacket has been removed; 
           [0080]      FIGS. 61A ,  61 B and  61 C are fragmentary, longitudinal-sectional views of the distal end of the insertion device with the outer jacket removed and respectively showing two locking rings, one locking ring and no locking ring; 
           [0081]      FIG. 62  is an exploded, perspective view of the insertion device of the embodiment of  FIG. 51 ; 
           [0082]      FIG. 63  is a fragmentary, longitudinal-sectional view of the proximal end and part of the working length of the insertion device of the embodiment of  FIG. 51 ; 
           [0083]      FIG. 64  is a greatly enlarged, fragmentary, side-longitudinal-sectional view of a proximal section of the insertion device of the embodiment of  FIG. 51 ; 
           [0084]      FIG. 65  is a fragmentary, top-longitudinal-sectional view of the proximal section of the insertion device of the embodiment of  FIG. 51 ; 
           [0085]      FIG. 66  is a fragmentary, side-longitudinal-sectional view of the proximal end of the insertion device of the embodiment of  FIG. 51 ; 
           [0086]      FIG. 67  is a fragmentary, top-longitudinal-sectional view of the proximal end of the insertion device of the embodiment of  FIG. 51  in the actuated condition; 
           [0087]      FIG. 68  is a fragmentary, top-longitudinal-sectional view of the proximal end of the insertion device similar to  FIG. 67 , in a non-actuated condition; and 
           [0088]      FIGS. 69A ,  69 B,  69 C and  69 D are enlarged, fragmentary, perspective views of the proximal end of the insertion device respectively showing a handle with a clamping plate, a body tube slid over the clamping plate, an end cap at the proximal end and a bobbin distally of the end cap. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0089]    Referring now to the figures of the drawings in detail and first, particularly to  FIG. 1  thereof, there is seen a variably flexible insertion device  1  according to an exemplary embodiment of the invention. The insertion device  1  has a hollow body with a proximal end  2  for manipulation by an operator and for receiving an instrument  32  such as an endoscope or colonoscope seen in  FIG. 5 . The insertion device  1  also has a distal end  3  for insertion into a patient and for protrusion of the instrument  32 . An outer handle  4  of the hollow body for the operator is disposed at the proximal end  2 . The handle  4  has a vacuum port  5  formed therein. An outer sleeve  6  of the hollow body is disposed between the outer handle  4  and a nose tip  7  of the hollow body at the distal end  3 . The outer sleeve  6  provides a flexible section with a given length extending beyond the handle  4 . 
         [0090]      FIG. 2  shows that the outer handle  4  contains an inner handle  30  of the hollow body having channel grooves  10  which permit movement of tendons  11 . The tendons  11  extend substantially entirely over the given length of the flexible section provided by the outer sleeve  6 . The tendons  11  may have a rounded or flattened cross section or a flattened cross section twisted along its length. A friction lock area  12  is disposed within the outer sleeve  6  for locking the tendons  11  in a manner to be discussed below. Vertebrae  13 - 17  are distributed along a flexible area  20  which is approximately 30 inches long. Whereas the vertebrae  14 - 17  allow movement of the tendons  11 , the first vertebra  13  closest to the distal end  3  is fixed to the tendons  11 . Although six vertebrae are shown, it is understood that more or fewer vertebrae may be provided, for example eight vertebrae, depending on the length of the device  1 . The number of tendons  11  is also variable, although twelve is used as an example. 
         [0091]    As seen in  FIG. 3 , a ring of locking pads  25  encircles the friction lock area  12 . Each tendon  11  is assigned a respective locking pad  25 , which is clearly shown in  FIG. 16 . The tendons  11  are disposed between the locking pads  25  and a friction surface  26  shown in  FIGS. 4 and 16 . The friction surface  26  is part of the inner handle  30  having the grooves  10  in which the tendons  11  move. 
         [0092]      FIG. 5  illustrates the outer handle  4  as well as the inner handle  30  with the channel grooves  10  for the tendons  11 . The outer handle  4  is shown as being transparent in  FIG. 5 , so as to be able to illustrate an entrance  32  for the surgical instrument  38 , such as an endoscope or colonoscope, a groove  33  for receiving an  0 -ring and the vacuum port  5 . 
         [0093]      FIG. 6  shows the region of the nose tip  7 . The tendons  11  are fixed and welded to the first vertebra  13 .  FIG. 7  also shows the tendons  11  fixed to the first vertebra  13  as well as the second vertebra  14  under which the tendons are free to move in the channel grooves  10  formed in the inner handle  30 . 
         [0094]    The sectional view of  FIG. 8  illustrates the outer sleeve  6 , the nose tip  7 , two tendons  11 , as well as the tendons being welded to the first vertebra  13  and being freely movable in the second vertebra  14 . An inner sleeve  35  of the hollow body is also shown in  FIG. 8 .  FIG. 8  additionally shows an end cap  37  to be snapped-on at the distal end to accommodate different sized instruments or scopes  38 . 
         [0095]      FIG. 9  shows how the tendons  11  are freely movable in the channel grooves  10  in the inner handle  30  and pass over the friction surface  26 . 
         [0096]      FIG. 10  also shows the friction locking pads  25 , the inner handle  30  with the grooves  10  and the tendons  11  passing through the grooves  10  and under the fifth vertebra  17 . The cross section of the vertebra  17  illustrated in  FIG. 15  additionally shows a coil  36  of the hollow body disposed within and supporting the inner sleeve  35 . The coil may be a wire which is TEFLON- or hydrophilic-coated to ease insertion of an endoscope or colonoscope. The stiffness or spring constant k of the coil  36  tends to maintain the device  1  in a straight condition. However, as will be explained in detail below, the device  1  does not remain straight when held horizontal in its flexible state. The coil  36  is used to maintain the round cross section of the device  1  while it is flexed. 
         [0097]    The view of  FIG. 11  shows the tendons  11  passing through the channel grooves  10  formed in the inner handle  30  and under the friction locking pads  25 . The tendons  11  are freely movable in the channel grooves  10 , except when pinched between the friction locking pads  25  and the friction surface  26  in the friction lock area  12 . 
         [0098]    The cross-sectional view of  FIG. 12  shows an O-ring  31  disposed in the groove  33 .  FIG. 14  shows a space  34  between the outer handle  4  and the inner handle  30 . The space  34  is sealed by the O-ring  31  and communicates with the vacuum port  5  for applying positive and negative pressure (vacuum) to the space. 
         [0099]      FIG. 13  is a cross-sectional view illustrating details of the friction lock area  12 . It may be seen that the tendons  11  which pass below the vertebrae  16 ,  17  are pinched between the friction locking pads  25  and the friction surface  26  in the friction area  12 . 
         [0100]    According to another embodiment of the invention which is illustrated in  FIG. 18 , the hollow body  4 ,  6 ,  7 ,  30 ,  35 ,  36  has a longitudinal slit  39  formed therein for radially loading the hollow body onto the instrument  38 . The slit has a closure  40 , such as a slide or press zipper used for plastic storage bags, permitting the device to be resealed after the hollow body has been loaded. The coil in this case is a ring wire, double wire, double loop or twin loop binding  41  seen in  FIG. 19 , such as is used for notebooks. 
         [0101]    The operation of the variably flexible insertion device  1  is best understood by making reference to  FIG. 17  in conjunction with the above-described figures. After the device  1  is forced into a flexed condition against the stiffness or spring constant k of the coil  36  as seen in  FIG. 17 , for example upon traversing the rectosigmoid junction, and it is desired to maintain that flexed condition for guiding an endoscope, such as a colonoscope, vacuum is applied to the space  34  through the vacuum port  5 . When suction is applied to create the vacuum, it causes the inner sleeve  35  and the outer sleeve  6  to firmly contact each other with the tendons  11  sandwiched and frictionally locked therebetween. Therefore, the vacuum port  5  acts as a device for transitioning the hollow body  4 ,  6 ,  7 ,  30 ,  35 ,  36  between the relatively flexible condition and the relatively stiff condition through the application of a vacuum. Most of the stiffness causing the device  1  to maintain its flexed condition is accomplished by this interaction of the inner and outer sleeves and the tendons. However, additional stiffness may optionally be accomplished by providing the friction locking pads  25  which contract and hold the tendons  11  against the friction surface  26  in the friction area  12 . The device  1  therefore maintains its flexed condition.  FIG. 17  shows that in the flexed condition, the tendons  11  at the outer periphery of the bend become shorter and the tendons  11  at the inner periphery of the bend become longer, since they are all fixed in place at the first vertebra  13 . 
         [0102]    The tendons or wires  11  are passive elements which are not in tension at any time. The tendons float within the hollow body when it is in the flexible condition, except at the distal end. The tendons are frictionally locked by the inner sleeve  35  and the outer sleeve  6  when the hollow body is in the stiff condition. However, in both the relatively flexible condition and the relatively stiff condition, the tendons have no active control imposed on them and are not pulled or constrained. 
         [0103]    When it is desired to resume flexibility of the device  1 , the vacuum in the space  34  is replaced by air at ambient or positive pressure. This causes the inner sleeve  35  and the outer sleeve  6  to release the tendons  11  and allows the stiffness or spring constant k of the coil  36  to place the device  1  into its normally flexible condition. If friction locking pads  25  are used, they also relax and expand, which in turn releases the tendons  11 . 
         [0104]    The device is intended to be used in a manner similar to prior art devices. Therefore, the device will be placed over the endoscope. The endoscope will then be inserted into the rectum. The device will then be pushed in its flexible condition, to follow the curvature of the scope. The device will then be stiffened, allowing the scope to be pushed forward with less pressure exerted on the colon of the patient. This procedure can be repeated until the scope reaches the cecum. 
         [0105]    An alternative use of the device is to aid in small bowel endoscopy. The device is placed over the endoscope. The endoscope is inserted into the patient transorally, through the stomach and then partially into the small bowel. The device is then pushed in its flexible condition, to follow the curvature of the scope. The device is then stiffened, allowing the scope to be pushed forward without the scope looping in the stomach. 
         [0106]    Another use of the device is for aiding in access to internal body parts, such as the gallbladder, through an opening of an internal body cavity, such as the stomach. The device is placed over the endoscope. The endoscope is inserted into the patient transorally, through the stomach and then up against the internal surface of the stomach. The device is then pushed in its flexible condition, to follow the curvature of the scope. The device is then stiffened, allowing the surgeon to create an opening in the stomach wall without the scope looping in the stomach. Once the opening is created, the device and the scope can be advanced outside the stomach. The device can then be stiffened to create a stable platform to perform surgical procedures outside of the stomach. The device could contain one or more features (i.e. balloons) for sealing the outer periphery of the device to the stomach wall to prevent gastric fluids from exiting the stomach. 
         [0107]    According to the other embodiment of the invention, the device is capable of being loaded on the instrument or scope after the scope is inserted into the patient. In this embodiment, the slit down the length of the device allows it to be loaded on the scope so that the scope is inserted radially into the hollow body. 
         [0108]    Referring now to  FIG. 20 , there is seen a torque-transmitting, variably-flexible, corrugated insertion device  100  according to another exemplary embodiment of the invention. The insertion device  100  has a hollow body with a proximal end  102  for manipulation by an operator and for receiving an instrument such as an endoscope or a colonoscope. The insertion device  100  also has a distal end  103  for insertion into a patient and for protrusion of the instrument. A handle  104  of the hollow body for control by the operator is disposed at the proximal end  102 . An outer jacket  105  of the hollow body extends to a tip  107 , which may be formed of rubber, at the distal end  103 , but only a portion of the outer jacket has been shown in order to illustrate other details of the device disposed within the outer jacket  105 . A flexible strain relief retainer  106  is disposed between the handle  104  and the outer jacket  105 . The outer jacket  105  and the flexible strain relief retainer  106  provide a flexible section with a given length extending beyond the handle  104 . The handle  104  has a sliding valve  28  and a septum valve assembly  29 , which will be explained in greater detail below with regard to  FIG. 21 . The handle  4  also has a vacuum connection or nipple  135  for controlling stiffness of the device, as will be explained below as well. A corrugated tube  130 , which is only illustrated in the region of the distal tip  107 , actually extends to the flexible strain relief retainer  106 . 
         [0109]    The insertion device  100  may be steerable or non-steerable. If the device is steerable, a steering assembly  110  is provided which includes six vertebrae  13 - 18  shown as being disposed along the hollow body. However, more or fewer vertebrae can be provided in dependence on the length, diameter and use of the hollow body. Eight tendons  11 ,  11 ′ are equally spaced apart about the circumference of the hollow body between the vertebra  17  and the handle  104 , although only five can be seen in  FIG. 20 . Four of the tendons which extend from a tendon termination bushing  131  at the tip  107  to the handle  104  are so-called steering tendons  11 ′. Other tendons which only extend between the vertebra  17  and the handle  104  are so-called non-steering tendons  11 . 
         [0110]    Each of the four steering tendons  11 ′ is attached at its proximal end to a respective knob  136  which slides within a respective slot  138  in the handle  104 . A stop  139  is also disposed on each tendon  11 ′. When a knob  136  is slid proximally, it pushes a stop  139  and pulls a tendon  11 ′ to steer the hollow body. In the condition shown in  FIG. 20 , the knob  136  at the bottom has been slid proximally so that the tip  107  of the hollow body has been steered downward. If different knobs  136  are moved, the hollow body will be steered in different directions. When the knobs  136  are forced distally, the knobs can freely slide independently of the tendons  11 ′ to prevent buckling of the tendons  11 ′. It will be readily understood that if two of the knobs are slid proximally, the tip  107  will move in a direction between the two directions that each one of the knobs would have moved the tip if moved individually. 
         [0111]    In  FIG. 21 , an outer covering of the handle  104  has been removed to show details of the sliding valve  28  and the septum valve assembly  29 . The handle  104  has an inner handle  119  disposed within an outer handle  118 , defining an annular vacuum plenum volume  124  therebetween which extends in longitudinal direction of the handle  104 . A vacuum inlet/outlet hole or port  125  is formed in the body of the outer handle  118  and communicates with the volume  124 . A sliding so-called tire valve thumb grip  120  encircles the outer handle  118  and is sealed thereto by O-ring seals having O-rings  121  in recesses  122  in the grip  120 . An O-ring seal is also disposed at the proximal end of the handle  104 . The grip  120  also has a vacuum inlet/outlet  123  for the connection or nipple  135 . When the grip  120  is slid toward an annular stop  126 , the vacuum inlet/outlet  123  is not in alignment with the vacuum inlet/outlet hole  125 . However, when the grip  120  is slid toward an annular stop  127 , the vacuum inlet/outlet  123  and the vacuum inlet/outlet hole  125  are aligned, providing communication between the connection or nipple  135  and the volume  124 . Therefore, during operation, the grip  120  is slid toward the stop  127  to apply vacuum to stiffen the hollow body or to vent the vacuum to the atmosphere or supply air at atmospheric pressure to make the hollow body flexible again. The grip  120  is slid toward the stop  126  to maintain the stiffened or flexible condition of the hollow body attained by vacuum or venting or air supply through the connection or nipple  135 . The septum valve assembly  29  is in the form of an end cap which is inserted into the proximal end of the outer handle  118  and provides a so-called septum seal for insertion of an instrument  44 , such as an endoscopy or a colonoscopy, represented by a dot-dash line. End caps with various sized openings may be used in dependence on the instrument being used. The instrument passes through the hollow body and emerges at the distal tip  107 . A diaphragm seal is provided between the septum valve assembly  29  and the inner handle  119 . 
         [0112]    If the insertion device  100  is non-steerable, the number of tendons  11  may also be varied as shown in  FIG. 22  to provide stiffness zones. For example, a stiffness zone A closest to the distal tip  107  has four tendons, a stiffness zone B has eight tendons and a stiffness zone C closest to the handle  104  has sixteen tendons. A zone with more tendons will be stiffer than a zone with fewer tendons. The number of tendons and their location within the zones as well as the number of zones can be increased or decreased, depending on the application of the device. Vertebrae  12 - 18 , which in this case are seven in number, are also shown. The four tendons in the zone A all end at the termination bushing  131  but are free to slide elsewhere. Four of the eight tendons in zone B, which do not extend to zone A, are fixed at the vertebra  14  between zones A and B, which is therefore referred to as a termination vertebra, but are free to slide elsewhere. Similarly, eight of the sixteen tendons in zone C, which do not extend into zones A and B, are fixed at the termination vertebra  16  between zones B and C but are free to slide elsewhere. 
         [0113]      FIG. 23  shows the device  100  with the handle  104  removed, from which it can be seen that the four steering tendons  11 ′ of the steering assembly  110  continue toward the handle from the tip  107 , whereas the non-steering tendons  11  only run from the termination vertebra  15  to the handle. It is also seen that as the insertion device is steered, the steering tendons  11 ′ on the outside of the bend become shorter and the steering tendons  11 ′ on the inside of the bend become longer.  FIG. 24  shows a similar view to  FIG. 23 , in which it can be seen how a greater number of vertebrae react to bending. In the case of  FIG. 24 , eight steering tendons  11 ′ extend to the termination bushing  131 , whereas six non-steering tendons  11  extend from the termination vertebra  18  to the handle. 
         [0114]    In the enlarged view of  FIG. 25 , a portion of the corrugated tube  130  in the region of the tip  107  and the termination bushing  131  are shown. The tendons  11 ,  11 ′, which have been omitted in  FIG. 25  for the sake of clarity, are shown in  FIG. 26  as extending through the vertebrae  13 ,  14  to the termination bushing  131 . A tip restrictor  132  can also be seen at the tip  107 . It may also be seen that an inner liner  133  extends within the corrugated tube  130 . One purpose of the inner liner is to provide a surface on which the instrument will pass smoothly within the corrugated tube. The corrugated tube  130  may be formed of nylon or another suitable material. The inner liner  133  is made from a sheet of white plastic material which has an adhesive coating on one side. The inner liner  133  is rolled around an inflatable mandrel and heated in an oven, to form a bonded seam  42  (shown in  FIGS. 30-32 ) and is sealed to an inner surface of the corrugated tube  130 . The corrugations of the corrugated tube  130  have peaks and valleys. As viewed from within the corrugated tube  130 , the inner liner  133  adheres to the peaks and extends somewhat into the valleys of the corrugations as dimples. Therefore, as the insertion device bends, the inner liner  133  stays tight along the corrugations on the outside of the bend and crinkles at the inside of the bend. The peaks and valleys of the corrugations also need not be of equal length along the length of the corrugated tube  130 . For example, 70% of the length may be peaks and 30% valleys or 80% of the length may be peaks and 20% valleys. These variations will add to the adhesion of the inner liner to the corrugated tube and reduce the formation of dimples. However, a 50/50 corrugation ratio is shown in the figures. The outer jacket  105  may be formed of polyurethane or another suitable material which is similarly a flat sheet that is rolled and seamed. The outer jacket  105  and the inner liner  133  both extend to the termination bushing  131 , which may be formed of polycarbonate. 
         [0115]    The corrugated tube is cuffed in order to prevent leakage paths for the vacuum applied within the hollow body and to protect the material of the inner liner.  FIG. 27  illustrates two types of molded corrugation cuffs  134 , namely a straight cuff on the left and a stepped cuff on the right, of the figure, both with a 50/50 corrugation ratio.  FIG. 28  shows the inner handle  119  which is attached to a corrugation cuff  134 , as well as the inner liner  133  that is sealed to the corrugated tube  130  and to the inner handle  119  to prevent a vacuum leakage path. 
         [0116]    The perspective view of  FIG. 29  illustrates the insertion device  100  in the region of the tip  107 , including the outer jacket  105  extending to the tip, which is not shown in the other figures. 
         [0117]    The fragmentary, perspective view of  FIG. 30  illustrates the insertion device  100  in the region of the tip  107 , with the outer jacket removed to reveal the termination bushing  131  at the tip  107 , the corrugated tube  130 , the vertebrae  13 ,  14 , the tendons  11  or  11 ′ and the inner liner  133 . It is seen that the tendons slide through channels  137  in the vertebrae. 
         [0118]    In  FIG. 31 , not only the outer jacket  105  but also the tip  107  have been removed to show how the tendons  11 ,  11 ′ are anchored in the termination bushing  131 . As can been seen, each tendon  11 ,  11 ′ passes through a respective hole  140  in the termination bushing  131 . Each two tendons together have a U-shape in the form of a large staple having a crosspiece  141  extending between two of the holes  140 . This avoids the necessity of welding ends of tendons to a terminating vertebra or ring. The U-shaped tendons and crosspiece are best seen in  FIG. 31A . 
         [0119]    In  FIG. 32 , not only the outer jacket  105  and the tip  107  but also the termination bushing  131  have been removed to show a portion of the inner liner  133  which is sealed on the inner surface of the termination bushing  131  for vacuum sealing and smooth movement of the instrument or scope  44 . The crosspieces  141  of the tendons  11 ,  11 ′ as well as the seam  42  of the inner liner are also clearly shown. 
         [0120]      FIG. 33  is a cross-sectional view of the insertion device  100  which is taken through the flexible tip restrictor  132 , as seen in the direction of the vertebra  13 . Therefore, the outer jacket  105 , the vertebra  13  with the tendons  11 ,  11 ′, the corrugated tube  130  with the peaks and valleys and the tip restrictor  132 , can be seen. 
         [0121]    Representative vertebrae  12 - 18  are shown in  FIGS. 34 and 35 . The vertebra of  FIG. 34  is a so-called latch ring constructed for snap installation. The vertebra is formed of elastic material which permits it to be expanded at a parting line and opened at a gap  43 , so that it can be snapped over the corrugated tube  130  between two peaks thereof. Therefore, the vertebra can be installed at any location desired along the corrugated tube for support of the tendons. The vertebra shown in  FIG. 35  is intended to be placed at an end of the corrugated tube  130 , where no expansion and snapping into place are required. 
         [0122]    The operation of the variably flexible insertion device  100  will now be described below by making reference to the above-described figures. If the steerable embodiment is used, the device  100  is flexed against the stiffness of the corrugated tube  130 , for example upon traversing the rectosigmoid junction, by sliding one or more of the knobs  136 . In either the steerable or non-steerable embodiment, if it is desired to maintain that flexed condition for guiding an endoscope, such as a colonoscopy, vacuum is applied at the connection or nipple  135 . When suction is applied to create the vacuum, it causes the inner sleeve  133  and the outer jacket  105  to approach each other with the corrugated tube  130  and the tendons  11 ,  11 ′ sandwiched and frictionally locked therebetween. Therefore, the vacuum connection or nipple  135  acts as a device for transitioning the hollow body  104 ,  107 ,  119 ,  105 ,  133 ,  130  between a relatively flexible condition and a relatively stiff condition through the application of a vacuum. As long as the vacuum is applied, the device  100  maintains its flexed condition. The positions of the knobs  136  in  FIGS. 20 ,  21 ,  23  and  24  show that in the flexed condition, the tendons  11 ′ at the outer periphery of the bend become shorter and the tendons  11 ′ at the inner periphery of the bend become longer, since they are all fixed in place at the termination bushing  131 . 
         [0123]    The tendons or wires are passive elements which are not in tension at any time. The tendons float within the hollow body when it is in the flexible condition, except where they are fixed to termination vertebrae or the termination bushing  31  at the distal end. The tendons are frictionally locked by the inner sleeve  133  and the outer jacket  105  when the hollow body is in the stiff condition. However, in both the relatively flexible condition and the relatively stiff condition, the tendons have no active control imposed on them and are not pulled or constrained. 
         [0124]    When it is desired to resume flexibility of the device  100 , the vacuum is vented or replaced by air at ambient or positive pressure. This causes the inner sleeve  133  and the outer jacket  105  to release the tendons and allows the stiffness of the corrugated tube  130  to place the device  100  into its normally flexible condition. 
         [0125]    In each surgical procedure using the device, the knobs and tendons are used to steer the insertion device within the body as needed, while the corrugated tube allows the device to be twisted as needed. 
         [0126]    Referring back to the figures of the drawings in detail and, in particular, to  FIG. 36  thereof, there is seen a steerable, variably-flexible insertion device  200  according to another exemplary embodiment of the invention. The insertion device  200  has a hollow body with a proximal end  202  for manipulation by an operator and for receiving an instrument such as an endoscope or a colonoscope. The insertion device  200  also has a distal end  203  for insertion into a patient and for protrusion of the instrument. A handle  204  of the hollow body for control by the operator is disposed at the proximal end  202 . The handle  204  has a vacuum connection or nipple  205  for controlling stiffness of the device, as will be explained below. An outer jacket  241  of the hollow body, which is disposed between the handle  204  and a tip  207  of the hollow body at the distal end  203 , is not shown in  FIG. 36 . The outer jacket  241 , which is shown in  FIG. 45 , provides a flexible section with a given length extending beyond the handle  204 . Whereas  FIG. 36  shows the hollow body steered to the right,  FIG. 37  shows it steered to the left and  FIG. 38  shows the hollow body in perspective. 
         [0127]    A steering assembly  210  of the device  200  includes five vertebrae  13 - 17  shown as being disposed along the hollow body. However, more or fewer vertebrae can be provided in dependence on the length, diameter and use of the hollow body. Eight tendons are shown as being equally spaced apart about the circumference of the hollow body. A first four of those tendons, identified as non-steering tendons and indicated by reference numeral  11 , extend only between the handle  204  and the vertebra  17  where they are fixed in place. A second four of those tendons, identified as steering tendons and indicated by reference numeral  11 ′, are spaced apart by 90° circumferentially and extend between the handle  204  and the distal-most vertebra  13  where they are fixed in place. Once again, a greater or lesser number of tendons may be used, as needed. The tendons may have a rounded or flattened cross section or a flattened cross section twisted along its length. The vertebrae to which the tendons are fixed may be referred to as weld rings since the tendons may be welded thereto. For example, all of the tendons  11 ′ are fixed to the vertebra  13 , such as by welding. At the vertebra  16 , for example, the steering tendons  11 ′ are permitted to slide, but the non-steering tendons  11  are welded or otherwise fixed in place. When welding is used for fixation, the tendons and vertebrae are normally made of stainless steel. However, the tendons and vertebrae may also be formed of plastic which is bonded or adhesively connected where desired. Both metal and plastic tendons and vertebrae may be used in one device. 
         [0128]    Four knobs  206  are each slideably disposed within a respective slot  208  in the handle  204 . Each of the steering tendons  11 ′ extend between the vertebra  13  and a respective one of the knobs  206 . Each steering tendon  11 ′ extends through a respective knob  206  and is connected to a respective stop  209 . When a knob  206  is slid proximally, it pushes a stop  209  and pulls a steering tendon  11 ′ to steer the hollow body. In the condition shown in  FIG. 36 , the knob  206  at the right has been slid proximally so that the tip  207  of the hollow body has been steered to the right. In the condition shown in  FIG. 37 , the knob  206  at the left has been slid proximally so that the tip  207  of the hollow body has been steered to the left. A similar result shown in  FIG. 38  has been accomplished by sliding one of the knobs  206  proximally. When the knobs  206  are forced distally, the knobs can freely slide independently of the steering tendons  11 ′ to prevent buckling of the steering tendons  11 ′. It will be readily understood that if two of the knobs are slid proximally, the tip  207  will move in a direction between the two directions that each one of the knobs would have moved the tip if moved individually.  FIG. 39  shows the device  200  with the handle  204  removed, from which it can be seen that the steering tendons  11 ′ of the steering assembly continue toward the handle from the tip  207 , whereas the non-steering tendons  11  stop. 
         [0129]    It is also possible, as shown in  FIG. 40 , to provide stiffness zones within the steering assembly  210 . For example, a stiffness zone A closest to the distal tip  207  has four tendons, a stiffness zone B has eight tendons and a stiffness zone C closest to the handle  204  has sixteen tendons. A zone with more tendons will be stiffer than a zone with fewer tendons. The number of tendons and their location within the zones as well as the number of zones can be increased or decreased, depending on the application of the device. The vertebrae are also shown. The four tendons in the zone A are all fixed at the upper most vertebra but are free to slide elsewhere. Four of the eight tendons in zone B, which do not extend to zone A, are fixed at the vertebra between zones A and B but are free to slide elsewhere. Similarly, eight of the sixteen tendons in zone C, which do not extend into zones A and B, are fixed at the vertebra between zones Band C but are free to slide elsewhere. 
         [0130]      FIG. 41  shows a cross-sectional view of the handle  204  of  FIGS. 36-38 , in which the connection or nipple  205 , knobs  206  and slots  208  are not shown. The handle  204  has an inner handle  219  disposed within an outer handle  218 , defining an annular vacuum plenum volume  224  therebetween which extends in longitudinal direction of the handle  204 . A vacuum inlet/outlet hole or port  225  is formed in the body of the outer handle  218  and communicates with the volume  224 . A sliding so-called tire valve thumb grip  220  encircles the outer handle  218  and is sealed thereto by O-ring seals having O-rings  221  in recesses  222  in the grip  220 . The grip  220  also has a vacuum inlet/outlet  223  for the connection or nipple  205 . When the grip  20  is slid toward an annular stop  226  as shown, the vacuum inlet/outlet  223  is not in alignment with the vacuum inlet/outlet hole  225 . However, when the grip  220  is slid toward an annular stop  227 , the vacuum inlet/outlet  223  and the vacuum inlet/outlet hole  225  are aligned, providing communication between the connection or nipple  205  and the volume  224 . Therefore, during operation, the grip  220  is slid toward the stop  227  to apply vacuum to stiffen the hollow body or to vent the vacuum to the atmosphere or supply air at atmospheric pressure to make the hollow body flexible again. The grip  220  is slid toward the stop  226  to maintain the stiffened or flexible condition of the hollow body attained by vacuum or venting or air supply through the connection or nipple  205 . 
         [0131]    And end cap  228  is inserted into a proximal end of the outer handle  218  for insertion of an instrument, such as an endoscope or a colonoscope. End caps with various sized openings may be used in dependence on the instrument being used. The instrument passes through the hollow body and emerges at the distal tip  207 . A diaphragm seal or so-called septum  229  is disposed between the end cap  228  and the inner handle  219 . A dot-dash line  230  represents an instrument inserted through the handles. 
         [0132]      FIGS. 42 and 43  show a handle  204  with an outer vacuum valve handle  235  which is ergonomically configured with a so-called handlebar shape to be gripped by the hand of an operator of the device. A tire valve thumb grip  220  is also provided in the embodiment of  FIGS. 42 and 43 , but has been omitted for clarity. The outer handle  235  is an alternative to the outer handle  218 . As can be seen from the cross section of  FIG. 43 , a vacuum source may be connected to a port  236  in the outer handle  235  and the vacuum inlet/outlet  223  of the tire valve thumb grip  220  may communicate with a vacuum inlet/outlet hole  237  leading to an annular vacuum plenum volume  239  between the outer handle  235  and an inner handle  238 . When the tire valve thumb grip  220  is slid so that the vacuum inlets/outlets  223  and  237  are misaligned, vacuum is supplied from the port  236  to the vacuum plenum volume  239 . When the tire valve thumb grip  220  is slid so that the vacuum inlets/outlets  223  and  237  are aligned, the plenum  239  is vented to the atmosphere. An end cap  234  is also shown. 
         [0133]      FIG. 44  illustrates a torque sheath or braided inner liner  240  of the insertion device  200 . The torque braid  240  is a woven tube formed of fabric, plastic, metal or a combination thereof, such as a metallized material. Steel or a polymer, such as polyethylene terephthalate or PET (sold under the trademark MYLAR) or PEEK (polyether ether ketone) are particularly useful. The purpose of the torque braid  240  is to transmit torque applied by the operator of the device at the proximal end  202  along the length of the hollow body up to the tip  207 . Therefore, the torque braid must be non-linearly compliant, that is it has a limited elongation in the linear direction. 
         [0134]    As is shown in the perspective view of  FIG. 45 , the torque braid  240  may be disposed in a space  244  between an outer jacket  241  and an inner sleeve  242 . In the illustrated embodiment, the torque braid  240  is disposed above the vertebra  15 , but the tendons have been omitted for clarity. The torque braid  240  may be placed in various locations, as will be described below with reference to  FIGS. 47-50 . The purpose of the torque braid  240  is to allow twisting of the hollow body as well as steering of the hollow body by the tendons while inserting the insertion device into the body. The torque braid  240  is typically provided over the full length of the hollow body, but may also be omitted at the tip  207  for additional flexibility or doubled, for instance, near the handle  204  for additional stiffness. 
         [0135]      FIG. 45  also shows a coil  243  of the hollow body which is provided within the inner sleeve  242  of the hollow body for supporting the inner sleeve. The coil may be a wire which is TEFLON- or hydrophilic-coated to ease insertion of an endoscope or colonoscope. The stiffness or spring constant k of the coil  243  tends to maintain the device  200  in a straight condition and is used to maintain the round cross section of the device  200  while it is flexed. 
         [0136]      FIG. 46  shows an alternative embodiment of the torque braid  240  and the tendons  11 ,  11 ′, in which the tendons are intermittently woven through the torque braid to eliminate the need for the vertebrae  13 - 17 . The tendons  11 ,  11 ′ travel under the torque braid  240  for about 2 inches and then are woven through one loop of the torque braid  240  to create weave points. This is repeated along the length of the device. The weave points act like the vertabrae in “attaching” the tendons  11 ,  11 ′ to the body of the device but letting the tendons slide through. Using the torque braid in this way eliminates the need for the vertebrae thus decreasing the outer diameter of the device, lowering the cost of the device and simplifying the structure thereof. It is noted that the tendons are shown as being flexed as they weave through the torque braid for clarity of the illustration. In actuality there will be some amount of flex in both the torque braid and the tendons, but mostly on the part of the torque braid. The tendons could also be woven in the opposite way, that is laid on top of the braid and woven down into it. 
         [0137]      FIGS. 47-50  are cross-sectional views of the device, in which the torque braid  240  is placed in various locations. In each of the figures, as seen from the exterior toward the interior, the insertion device  200  includes the outer jacket  241 , the space  244 , the vertebrae  13 - 17  (reference numeral  15  is used as an example), the inner sleeve  242  and the coil  243 , although the latter is merely shown in outline form for the sake of clarity. It is also seen that the vertebrae  13 - 17  have channels  245  formed therein permitting movement of the tendons  11 ,  11 ′ which are not fixed in place. 
         [0138]    In the embodiment of  FIG. 47 , the torque braid  240  is disposed between the coil  243  and the inner sleeve  242 . In the embodiment of  FIG. 48 , the torque braid  240  is disposed between the inner sleeve  242  and the vertebra  15 . In the embodiment of  FIG. 49 , the torque braid  240  is disposed between the vertebra  15  and the outer jacket  241 . In the embodiment of  FIG. 50 , the torque braid  240  may be disposed within the coil  243 . 
         [0139]    The operation of the variably flexible insertion device  200  will now be described below by making reference to the above-described figures. The device  200  is flexed against the stiffness or spring constant k of the coil  243 , for example upon traversing the rectosigmoid junction, by sliding one or more of the knobs  206 . If it is desired to maintain that flexed condition for guiding an endoscope, such as a colonoscope, vacuum is applied at the connection or nipple  205  in the embodiment of  FIG. 41  or at the vacuum port  236  in the embodiment of  FIG. 43 . When suction is applied to create the vacuum, it causes the inner sleeve  242  and the outer jacket  241  to firmly contact each other with the tendons  11 ,  11 ′ sandwiched and frictionally locked therebetween. Therefore, the vacuum connection or nipple  205  or the vacuum port  236  acts as a device for transitioning the hollow body  204 / 235 ,  207 ,  219 / 238 ,  241 ,  242 ,  243  between a relatively flexible condition and a relatively stiff condition through the application of a vacuum. As long as the vacuum is applied, the device  200  maintains its flexed condition. The positions of the knobs  206  in  FIGS. 36-38  show that in the flexed condition, the tendons  11 ′ at the outer periphery of the bend become shorter and the tendons  11 ′ at the inner periphery of the bend become longer, since they are all fixed in place at the first vertebra  13 . 
         [0140]    The tendons or wires are passive elements which are not in tension at any time. The tendons float within the hollow body when it is in the flexible condition, except where they are fixed to vertebra, such as at the distal end. The tendons are frictionally locked by the inner sleeve  242  and the outer jacket  241  when the hollow body is in the stiff condition. However, in both the relatively flexible condition and the relatively stiff condition, the tendons have no active control imposed on them and are not pulled or constrained. 
         [0141]    When it is desired to resume flexibility of the device  200 , the vacuum is vented or replaced by air at ambient or positive pressure. This causes the inner sleeve  242  and the outer jacket  241  to release the tendons and allows the stiffness or spring constant k of the coil  243  to place the device  200  into its normally flexible condition. 
         [0142]    In each surgical procedure using the device, the knobs and tendons are used to steer the insertion device within the body as needed, while the torque braid allows the device to be twisted as needed. 
         [0143]    Referring back to the figures of the drawings in detail and, in particular, to  FIGS. 51 and 52  thereof, there is seen a torque-transmitting, variably-flexible, locking insertion device  300  according to the invention having a working length. The insertion device  300  has a hollow body with a proximal end  302  for manipulation by an operator and for receiving an instrument  340  such as an endoscope or a colonoscope, shown in  FIG. 63 . The insertion device  300  also has a distal end  303  for insertion into a patient and for protrusion of the instrument. A handle  304  of the hollow body for control by the operator is disposed at the proximal end  302 . An outer jacket or sleeve  305  of the hollow body extends to a tip  306 , which may be formed of rubber, at the distal end  303 . As will be explained below, the handle  304  has an end cap  308 , an actuator or bobbin  309  for locking an instrument, a sliding valve or slider  310  and a forward stop  311 . The handle  304  also has a vacuum connection or nipple  312  for controlling stiffness of the device, as will be explained below as well. A corrugated tube  315  in the region of the distal tip  306 , which is illustrated in other figures, extends to the coupler  335 . 
         [0144]      FIGS. 53 ,  54  and  55  are enlarged perspective, top and side views showing the insertion device  300 , from which the end cap  308 , the actuator or bobbin  309 , the handle  304 , the sliding valve or slider  310  with the nipple  312 , the forward stop  311  and the strain relief retainer, can be seen more clearly.  FIG. 53  also shows the outer jacket  305  and the distal tip  306 . 
         [0145]      FIGS. 56 and 58  are perspective views of the entire insertion device  300  and  FIG. 57  is a fragmentary side view of the proximal end and part of the working length of the insertion device, in which the outer jacket  305  has been removed. It can therefore be seen that the corrugated tube  315  extends distally beyond the strain relief retainer to the tip  306  and that vertebrae  16  are clipped between several of the corrugations. Although only five vertebrae are shown in  FIGS. 56 and 58 , as many as twelve or more may be provided, depending on the working length and the application for which the insertion device is intended. The vertebrae may have slits formed radially therein to aid in slipping them over the corrugated tube. The last vertebra in the distal direction is a locking ring or termination vertebra  17 . Whereas  FIGS. 56 and 57  show the insertion device in the unlocked condition,  FIG. 58  shows it in the locked condition, which will be discussed in more detail below.  FIGS. 56 ,  57  and  58  also show staples or tendons  318  extended axially along the outer periphery of the corrugated tube  315 . 
         [0146]    As is seen in the fragmentary side, perspective and longitudinal-sectional views of  FIGS. 59A and 59B ,  60 A and  60 B and  61 A,  61 B and  61 C, the tendons or staples  318  are looped through holes or slits  322  in the vertebrae  16  and the locking ring  17 . The locking rings  17  have been omitted in  FIGS. 59B and 60B  to show details of the tendons or staples  318 . The tendons or staples  318  have ends  319  extending proximally, as shown in  FIG. 62 . The tendons or staples  318  may be fixedly connected to the locking ring  17 , such as by adhesive, weldments or solder joints. However,  FIGS. 59B and 61A ,  61 B and  61 C show that the tendons or staples  318  have a U-shape with legs passing through the holes  322  in the vertebrae  16  and cross pieces  320  disposed just distally beyond the locking ring  17 . It can be seen particularly clearly in  FIG. 61A  that the cross pieces  20  of the tendons or staples  318  are captured and prevented from migrating distally by two locking rings  17  between which the cross pieces H are sandwiched in a valley or trough between two peaks or crests of the corrugated tube  315 . 
         [0147]    The number and location of the tendons or staples  318  and the vertebrae  16  axially and circumferentially may be chosen in such a way as to vary the stiffness of the insertion device  300  in zones. For example, more tendons or staples  318  and/or more vertebrae  16  may be placed in one zone along the working length than in another zone. The zone with more tendons or staples and/or vertebrae will be stiffer. Additionally, some of the tendons or staples may not extend over the entire working length and some may be fixed to vertebrae along the working length, all of which also varies stiffness in zones. As the insertion device flexes, some of the tendons or staples which are not fixed to particular vertebrae slide in the holes or slits  322 . 
         [0148]    The exploded view of  FIG. 62  and the assembled sectional view of  FIG. 63  show the end cap  308  at the proximal end, which surrounds a rear bushing  316 . It may be seen that a marker band  328  is disposed between the actuator or bobbin  309  and the end cap  308 . A clamping plate  330 , which is also disposed within the actuator or bobbin  309 , has three partial-plates  331   a ,  331   b ,  331   c  between which three springs  332  are disposed. A body tube  333 , having slots  51 , is disposed distally of the clamping plate  330 . 
         [0149]    A coupler  335 , having grooves  323  extended axially on the periphery thereof, carries a septum seal  337  and an O-ring  338  provides a seal between the coupler  335  and the handle  304 , which is slid over the coupler  335 . Other marker bands  329  are disposed between the handle  304  and the sliding valve or slider  310  and the forward stop  311  is disposed over the distal end of the handle  304 . O-rings  324  provide a seal between the slider  310  and the handle  304 . An O-ring  334  is disposed between the forward stop  311  and the handle  304 . It may also be seen that a heat shrink tubing  339  covers the coupler  335  and an inner liner or sleeve  336  is disposed within the corrugated tube  315 . Moving distally, the corrugated tube  315  carrying the vertebrae  16 , the tendons or staples  318 , the locking ring  17  and the distal tip  306 , is shown as well. 
         [0150]    The inner sleeve  336  provides a surface over which the instrument  340  will pass smoothly within the corrugated tube  315 . The corrugated tube  315  may be formed of nylon or another suitable material. The inner sleeve  336  may be made from a sheet of polyester film, which has an adhesive coating on one side. The inner sleeve  336  is rolled around an inflatable mandrel and heated in an oven, to form a bonded seam and is sealed to an inner surface of the corrugated tube  315 . The corrugations of the corrugated tube  315  have peaks and valleys, as mentioned above. As viewed from within the corrugated tube  315 , the inner sleeve  336  adheres to the peaks and extends somewhat into the valleys of the corrugations as dimples. Therefore, as the insertion device bends, the inner sleeve  336  stays tight along the corrugations on the outside of the bend and crinkles at the inside of the bend. The peaks and valleys of the corrugations also need not be of equal length along the length of the corrugated tube  315 . For example, 70% of the length may be peaks and 30% valleys or 80% of the length may be peaks and 20% valleys. These variations will add to the adhesion of the inner sleeve  336  to the corrugated tube  315  and reduce the formation of dimples. However, a 50/50 corrugation ratio is shown in the figures. 
         [0151]    The outer jacket  305  may be formed of polyurethane or another suitable material which is similarly a flat sheet that is rolled and seamed. The outer jacket  305  extends to the distal tip  306  and the inner sleeve  336  terminates with the end of the corrugated tube  315 , the ends of which are “cuffed” to allow attachment of components. 
         [0152]    The sectional views of  FIGS. 64 and 65  show greater detail of the construction of the slider or sliding valve  310  having the nipple  312 . The slider  310 , which encircles the handle  304 , has a sliding so-called tire valve thumb grip  313  and is sealed thereto by the O-rings  324  which are disposed in recesses  314  in the handle  304 . 
         [0153]    It may be seen that the handle  304  and the coupler  335  define an annular vacuum plenum volume  341  therebetween which extends in longitudinal direction of the handle  304 . The O-ring  2  provides a seal at the proximal end of the volume  341 . A vacuum inlet/outlet hole or port  342  is formed in the body of the handle  304  and communicates with the volume  341 . The sliding valve or slider  310  also has a vacuum inlet/outlet  343  for the connection or nipple  312 . When the slider  310  is slid toward an annular stop  344 , the vacuum inlet/outlet  343  is not in alignment with the vacuum inlet/outlet hole  342 . However, when the slider  310  is slid toward an annular stop  345 , the vacuum inlet/outlet  343  and the vacuum inlet/outlet hole  342  are aligned, providing communication between the connection or nipple  312  and the volume  341 . Therefore, during operation, the slider  310  is slid toward the stop  345  to apply vacuum to stiffen the hollow body. The slider  310  is slid toward the stop  344  to vent the vacuum to atmospheric pressure making the hollow body flexible again. 
         [0154]    When vacuum is applied to the volume  341  in the manner described above, the outer jacket  305  and the corrugated tube  315  approach each other with the staples or tendons  318  sandwiched and frictionally locked therebetween. Therefore, the vacuum connection or nipple  312  acts as a device for transitioning the hollow body  304 ,  306 ,  335 ,  305 ,  336 ,  315  between a relatively flexible condition and a relatively stiff condition through the application of a vacuum. As long as the vacuum is applied, the insertion device  300  maintains its condition, whether flexed or straight. When it is desired to resume flexibility of the insertion device  300 , the vacuum is vented or replaced by air at ambient or positive pressure. This causes the corrugated tube  315  and the outer jacket  305  to release the tendons or staples  318  and the corrugated tube  315  and allows the inherent stiffness of the corrugated tube  315  to place the insertion device  300  into its normally flexible condition. 
         [0155]    The tendons, staples or wires  318  are passive elements which are not in tension at any time. The tendons or staples float within the hollow body  304 ,  306 ,  335 ,  305 ,  336 ,  315  when it is in the flexible condition, except where they are fixed to the locking rings  17 . The tendons or staples are frictionally locked by the corrugated tube  315  and the outer jacket or sleeve  305  when the hollow body is in the stiff condition. However, in both the relatively flexible condition and the relatively stiff condition, the tendons or staples have no active control imposed on them and are not pulled or constrained. 
         [0156]    As mentioned above, a comparison between  FIGS. 56 and 58  reveals that the actuator or bobbin  309  in  FIG. 56  is adjacent the end cap  308  in a non-actuated condition, while in  FIG. 58  the actuator or bobbin  309  is in an actuated condition, in which it has been moved over an extension  347  of the handle  304  and against a collar  348  of the handle  304 .  FIGS. 66 and 68  also show the actuator or bobbin  309  in the non-actuated condition, whereas  FIG. 67  shows the actuator or bobbin in the actuated condition, but in greater detail. 
         [0157]    As is seen in  FIGS. 62-63 ,  66 - 68  and  69 A,  69 B and  69 C, the three partial-plates or partial-shells  331   a ,  331   b ,  331   c  of the clamping plate  330  have detents  350  protruding therefrom.  FIGS. 67 ,  68  and  69 A,  69 B and  69 C in particular show that the springs  332  bias the partial-plates and therefore the detents  350  through slots  351  in the body tube  333  and into corresponding recesses  352  in the inner peripheral surface of the actuator or bobbin  309  in the non-actuated condition. When a sliding, so-called tire valve thumb grip  353  of the actuator or bobbin  309  is pushed by the operator of the device and the actuator or bobbin is slid distally toward the collar  348  of the handle  304 , the detents  350  slide out of the recesses  352  against the force of the springs  332 . This causes the partial-plates  331   a ,  331   b ,  331   c  to move toward each other radially and against the instrument  340 , such as an endoscope or a colonoscope represented by a dot-dash line in  FIG. 63 , for holding the instrument in place. When the actuator or bobbin  309  is slid proximally, the detents  350  once again fall into the recesses  352  due to the force of the springs  332 , so that the partial-plates  331   a ,  331   b ,  331   c  move radially outwardly and release the instrument  340 . Therefore, the actuator or bobbin  309  and the clamping plate  330  form a locking and unlocking device to be activated by the operator for locking the handle  304  to and unlocking the handle  304  from the instrument  340 . 
         [0158]      FIGS. 66 ,  67  and  68  also show the septum seal or valve assembly  337  in greater detail, as well as the end cap  308  which is inserted into the proximal end of the handle. End caps  308  with various sized openings may be used in dependence on the instrument being used. The instrument passes through the hollow body and emerges at the distal tip  306 . It may be seen that the septum seal or septum valve assembly  337  has a diaphragm  337 ′ resting in a recess in the coupler  335 . 
         [0159]    A comparison of  FIGS. 69A ,  69 B,  69 C and  69 D also shows that in  FIG. 69A  merely the handle  304  with the extension  347  and the collar  348  as well as the partial-plates  331   a ,  331   b ,  331   c  are shown, while the body tube  333  has been slid over the partial-plates in  FIG. 69B , the end cap  308  has been added at the proximal end in  FIG. 69C  and the actuator or bobbin  309  has been added distally of the end cap in  FIG. 69D .