Patent Publication Number: US-2011060183-A1

Title: Multi-instrument access devices and systems

Description:
This application claims the benefit of U.S. Provisional Application No. 61/153,644, filed Feb. 19, 2009, and U.S. Provisional Application No. 61/159,805, filed Mar. 13, 2009. This application is also a continuation-in-part of U.S. application Ser. No. 12/209,408, filed Sep. 12, 2008, which claims the benefit of U.S. Provisional Application No. 60/971,903, filed Sep. 12, 2007. Each of the aforementioned patent applications is incorporated herein by reference. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to the field of access devices through which medical instruments may be introduced into an incision or puncture opening formed in a body wall. 
     BACKGROUND 
     Surgery in the abdominal cavity is frequently performed using open laparoscopic procedures, in which multiple small incisions or ports are formed through the skin and underlying muscle and peritoneal tissue to gain access to the peritoneal site using the various instruments and scopes needed to complete the procedure. The peritoneal cavity is typically inflated using insufflation gas to expand the cavity, thus improving visualization and working space. Further developments have lead to systems allowing such procedures to be performed using only a single port. 
     In single port surgery (“SPS”) procedures, it is useful to position a device within the incision to give sealed access to the operative space without loss of insufflation pressure. Ideally, such a device provides sealed access for multiple instruments while avoiding conflict between instruments during their simultaneous use. The present application describes multi-instrument access devices suitable for use in SPS procedures and other laparoscopic procedures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 through 14  illustrate a first embodiment of a multi-instrument access device, in which: 
         FIG. 1  is a perspective view a first embodiment of the multi-instrument access device, together with a clamp attachable to the multi-instrument access device for use in coupling the device to a supportive arm attached to an operating table or other operating room structure; 
         FIG. 2A  is a partially exploded perspective view of a distal portion of the main tube; 
         FIG. 2B  is a partially exploded perspective view of the proximal ends of the passive access tubes; 
         FIG. 3  is a partially exploded perspective view of the main tube and proximal fitting of the system of  FIG. 1 . The proximal fitting is shown in transverse cross-section; 
         FIG. 4  is a longitudinal cross-sectional perspective view of the main tube and proximal fitting; 
         FIG. 5  is a perspective view of the proximal fitting; 
         FIG. 6A  is a perspective view of the instrument delivery tubes and actuators; 
         FIG. 6B  is a plan view of the instrument delivery tube shown in  FIG. 6A ; 
         FIG. 6C  is a plan view similar to  FIG. 6B  showing an alternate instrument delivery tube; 
         FIG. 7A  is a longitudinal cross-section view of one of the members of the proximal fitting, showing the coupling member engaged in a first longitudinal position; 
         FIG. 7B  is similar to  FIG. 7A  and shows the coupling member in a second longitudinal position; 
         FIGS. 8A-8C  are elevation views of the proximal end of the proximal fitting and show the coupling members engaged in different ones of the longitudinal slots; 
         FIG. 9A  is a perspective view similar to  FIG. 1  but showing the instrument delivery tubes in a closed axial position; 
         FIG. 9B  is a perspective view similar to  FIG. 9A  but showing the instrument delivery tubes in an intermediate axial position; 
         FIG. 10A  is similar to  FIG. 9A  but shows the system using the alternate instrument delivery tubes shown in  FIG. 6C  in the closed axial position; 
         FIG. 10B  is a plan view of the instrument delivery tubes of the embodiment of  FIG. 10A ; 
         FIG. 10C  is similar to  FIG. 10B  but shows the instrument delivery tubes in the intermediate axial position; 
         FIG. 10D  is similar to  FIG. 10B  but shows the instrument delivery tubes in the fully deployed position; 
         FIG. 11A  is a longitudinal cross-section view of a proximal portion of an instrument delivery tube, an actuator, and a distal portion of a control tube; 
         FIG. 11B  is an exploded view of the actuator of  FIG. 11A ; 
         FIG. 12A  is a perspective view showing instruments in use in the multi-access system; 
         FIG. 12B  is similar to  FIG. 12A  and shows deflection of an instrument used in an instrument delivery tube; 
         FIG. 13  is a perspective view of a proximal portion of an instrument delivery tube, an alternative actuator, and a distal portion of a control tube; 
         FIG. 14  is a perspective view of the alternative actuator of  FIG. 13 . 
         FIGS. 15-21  show a second embodiment of a multi-instrument access system in which: 
         FIG. 15  is a perspective view of the multi-instrument access device, showing the instrument delivery tubes in the closed position; 
         FIG. 16  is similar to  FIG. 15  but shows the instrument delivery tubes in an expanded or deployed position; 
         FIG. 17  schematically illustrates positioning of the base through an incision in an abdominal wall; 
         FIG. 18  is a perspective view of the base; 
         FIG. 19  is a perspective view of the seal and associated features, without the instrument delivery tubes; 
         FIG. 20  is an exploded view of the seal and associated features of  FIG. 19 ; 
         FIG. 21  is a perspective view showing an instrument delivery tube and actuator; 
         FIGS. 22 through 29  are figures showing a third embodiment of a multi-instrument access system in which: 
         FIG. 22  is a perspective view showing the multi-instrument access system in the deployed position; 
         FIG. 23  is a perspective view of the upper housing, base and detachable ports of the system of  FIG. 10 ; 
         FIG. 24  is a partially exploded view of the components of  FIG. 23 ; 
         FIG. 25  is an exploded view of the ports and plate; 
         FIG. 26  is a perspective view of the upper housing of the third embodiment, and may also be used in a modified version of the second embodiment; 
         FIG. 27  is a cross-section view of the upper housing; 
         FIG. 28  is a close-up view of a portion of the third embodiment, with the detachable ports removed to allow the bushings to be seen; 
         FIG. 29  is a perspective view of a bushing. 
         FIGS. 30-32B  are figures illustrating a third embodiment, in which: 
         FIG. 30  is a perspective view of the proximal housing and instrument delivery tubes; 
         FIG. 31A  is a perspective view of the proximal housing; 
         FIG. 31B  is a cross-section view taken along the plane designated  31 B- 31 B in  FIG. 31A ; 
         FIG. 32A  is a perspective view of a portion of the instrument delivery tube, a guide, and a portion of the corresponding post; 
         FIG. 32B  is similar to  FIG. 32A  but shows the instrument delivery tube axially rotated from the position shown in  FIG. 32A ; 
         FIG. 32C  is similar to  FIG. 32A  but shows the instrument delivery tube advanced longitudinally from the position shown in  FIG. 32A . 
     
    
    
     DETAILED DESCRIPTION 
     The accompanying figures illustrate multi-instrument access devices. In a first embodiment shown in  FIG. 1 , the access device  10  includes a base or main tube  12  positionable within an opening (e.g. an incision or puncture) formed in a body wall, namely through the skin and underlying tissue, to give access to a body cavity such as the peritoneal cavity. In some procedures, the opening may be formed through the umbilicus for purposes of cosmesis. During use, the tube remains disposed through the body wall opening and serves as the conduit through which the distal ends of multiple instruments are passed for use within the body cavity. In the illustrated embodiment, the main tube  12  provides access for introduction of up to four instruments into the body cavity via a pair of deflectable instrument delivery tubes  16 , and a pair of passive access tubes  26 ,  28 . Modifications to these embodiments within the scope of the invention can provide access for fewer or more than four instruments. 
     Main tube  12  is a rigid tube preferably having a single lumen. The outer diameter of the tube is preferably between 14-25 mm. The passive access tubes  26 ,  28  have proximal ends positioned external to the proximal end of the main tube  12  and distal ends disposed within the main tube  12  as shown in  FIG. 2A . The portions of the access tubes  26 ,  28  extending through the main tube  12  may be integral with the proximal portions visible in  FIG. 1 , or each of the access tubes  26 ,  28  may be formed of one or more separate tubes longitudinally connected or coupled to one another. As shown in  FIG. 2B , cross-slit seals  25  seal the lumen of the access tubes  26 ,  28 , and septum type lead seals  27  (shown exploded from the access tubes) are positioned to seal against the shafts of instruments positioned within the tubes  26 ,  28 . In the illustrated embodiment, the cross-slit seals  25  are part of a first cap that attaches to the seals, and the septum seals  27  are part of a second cap disposed on the first cap. 
     Referring again to  FIG. 1 , the distal end of the main tube  12  may include a partitioning element  14  that assists in maintaining the relative transverse positions of the instrument delivery tubes  16  and the shafts of instruments passing through the passive access tubes  26 ,  28 .  FIG. 2A  shows the partitioning element  14  exploded from the main tube  12 . In this embodiment, the partitioning element  14  defines first exit ports  30  through which the instrument delivery tubes  16  extend as shown in  FIG. 1 , and second and third exit ports  32 ,  34  longitudinally aligned with the passive access tubes  26 ,  28 . A standoff  40  also extends through the main tube  12  and is coupled to the partitioning element  14  using a fastener  42 . 
     In this embodiment, the partitioning element also forms an atraumatic distal tip for the main tube  12  due to the convex curvature of its outer surface. 
     Referring to  FIG. 3 , a proximal seal  44  partially or fully disposed within the proximal portion of the main tube  12 . The instrument delivery tubes  16  (not shown) and the passive access tubes  26 ,  28  (shown in cross-section) extend through corresponding openings in the proximal seal  44 . O-rings  45  may be positioned at the openings in the proximal seal  44  to seal around the shafts of the instrument delivery tubes  16  and/or the passive access tubes  26 ,  28 . 
     As shown in the longitudinal cross-section of  FIG. 4 , the proximal end of the main tube  12  extends into a proximal fitting  48 . An annular seal  46  also disposed within the proximal fitting  48  forms a seal between the outer surface of the main tube  12  and the surrounding wall of the proximal fitting  48 . A threaded fastener  50  ( FIG. 3 ) extends through an opening in the proximal fitting  48  and is engaged with the bore of the standoff  40  so as to retain the proximal fitting  48  against the proximal end of the main tube  12 . 
     The proximal fitting includes a base  52  ( FIG. 5 ) through which the instrument delivery tubes  16  and the passive access tubes  26 ,  28  extend. The base includes first openings  56  which accommodate the instrument delivery tubes  16  (not shown), and second and third openings  58 ,  60  which accommodate the inner tubes  26 ,  28 . Members  54  extend proximally from the base  52  on opposite sides of the openings  56 ,  58 ,  60 .  FIG. 5  illustrates that each member  54  includes a plurality of longitudinally extending channels  62   a ,  62   b ,  62   c  each having an opening at the proximal face of the member  54 . Circumferential slots  64   a ,  64   b ,  64   c ,  64   d  are formed in each member such that each longitudinal channel  62   a - c  intersects with each circumferential slot  64   a - d.    
     Referring again to  FIG. 1 , the instrument delivery tubes  16  extend through the proximal fitting  48  and the main tube  12 . In the illustrated embodiment, two such instrument delivery tubes are used, although alternative embodiments might use only one instrument delivery tube, while other embodiments might use three or more. Each instrument delivery tube  16  has a pre-shaped fixed curve or angle in its distal region  66 . 
     Referring to  FIG. 6A , each instrument delivery tube  16  includes a rigid section  18  and a flexible section  20  extending from the distal end of the rigid section  18 . Actuators  22  on the proximal portion of the access device  10  control deflection of the flexible distal sections  20  of the instrument delivery tubes  16  to allow manipulation of the operative ends of the instruments disposed within the instrument delivery tubes  16 . As will be described in detail below, the distal ends of instruments to be deployed into the body cavity via the instrument delivery tubes are inserted into control tubes  24  on the actuators  22  and then advanced into and through the instrument delivery tubes. Manipulating the proximal handles of the instruments in turn moves the control tubes  24 , causing corresponding deflection of the distal ends of the instruments. 
     Features of the instrument delivery tubes will next be described with respect to  FIGS. 6A and 6B . Each instrument tube  16  includes a rigid tube  18  which may be formed of stainless steel or other rigid tubing. Each rigid tube  18  may be a singular tube, or a series of tubes coupled together. The stiffener tubes may all have the same size and/or geometry, or two or more different sizes and/or geometries may be used. 
     As shown in  FIG. 6B , each rigid tube  18  is manufactured to have a fixed, preformed shape that includes a generally straight main section  70  and a distal region  66  which includes a bend to create a curved or angled section  68 . The curvature of the bend in the curved or angled section may be continuous or compound, and it can be formed to occupy a single plane or multiple planes. The shape of the rigid tubes  18  separates the distal regions  66  of the instrument delivery tubes, allowing instruments passed through the instrument delivery tubes  16  to be used at common treatment site when the instrument delivery tubes  16  are in the deployed position. 
     The curved section  68  shown in  FIG. 6B  has an elongated S-shape, with a more proximal section that curves downwardly relative to the longitudinal axis of the main section  70  and a more distal section that curves slightly upwardly. It should be noted that the terms “downwardly”, “upwardly” etc are used with reference to the drawings and not with reference to particular structures inside or outside the body cavity. The distal region  66  may additionally have a second straight section  72  distal to the curved or angled section  68 . In the  FIG. 6A  embodiment, the longitudinal axis of the straight section  72  is shown parallel to that of the straight main section  70 , however it may alternatively diverge towards or away from the longitudinal axis of the base  12 . 
     For the instrument delivery tube shown in  FIG. 6B , the longitudinal axes of the straight shaft  70 , curve  68  and distal end section  72  lie within a single plane, while a proximal bend section  74  of the tube  18  curves laterally out of that plane as well as downwardly. The proximal curvature of the proximal bend section  74  angles the actuators  22  away from one another in order to prevent interference between the handles of instruments used in the instrument delivery tubes  16  and instruments used in the passive tubes  26 ,  28 . 
     Various alternative shapes for the tube  18  other than those shown in the illustrated embodiments may instead be used. For example, as shown in  FIG. 6C , the bend may form a section  68   a  having a single curve or an angle extending from the straight shaft  70 , rather than an s-shaped curve. 
     The instrument delivery tubes  16  also include flexible inner tubes  20  extending through the rigid tubes  18 . Each inner tube  20  has distal and proximal sections  76 ,  78  extending beyond the distal and proximal ends, respectively, of the corresponding rigid tube  18 . The inner tubes  20  can be made with or without a pre-formed curve or angle. 
     Each inner tube  20  includes a lumen for receiving an instrument that is to be used within the body. A plurality of actuation elements such as pull wires or cables  72  extend through pullwire lumens in the wall of the inner tube  20  and are anchored near its distal end in the distal section  76 . In the preferred embodiment, each instrument delivery tube has four such wires arranged at 90 degree intervals. Other embodiments can utilize different numbers of pullwires, such as three pullwires equally spaced around each inner tube  20 . 
     As will be discussed in detail below, the pullwires for each of the flexible tubes  20  are coupled to a corresponding one of the actuators  22  ( FIG. 1 ), which act on the pull-wires to deflect the distal sections  76  of the flexible tubes  20 . The inner tubes  20  are therefore constructed to be sufficiently flexible to allow the required deflection for instrument manipulation, while preferably also being resistant to kinking. In one embodiment, each flexible tube  20  is a composite tube formed using a PFTE inner liner lining the lumen, a thermal plastic sheath (having the pull wire lumens formed through it) overlaying the liner, a reinforcing layer over the thermal plastic sheath, and a second thermal plastic sheath over the reinforcing layer. In an alternate embodiment, the second thermal plastic sheath is eliminated and the reinforcing layer serves as the outer layer of the sheath. In yet another embodiment, the reinforcing layer may comprise the most inner layer of the tube. Various other embodiments, including those provided without reinforcing layers, or those having additional layers of reinforcing material or other materials can also be used. 
     Each such delivery tube  16  is longitudinally slidable and selectively retainable in a plurality of predetermined longitudinal positions to lengthen or shorten the amount of the instrument delivery tube extending from the main tube  12  into the body cavity. The instrument delivery tubes are also axially rotatable and selectively retainable in a plurality of predetermined axial orientations, allowing the user to choose the appropriate axial position of the curved distal region  66 . 
     With regard to axial orientation, the instrument delivery tubes  16  can be retained in at least two pre-determined axial positions: (a) a closed or insertion position ( FIGS. 9A ,  10 A and  10 B) and (b) a fully open or deployed position ( FIGS. 1 and 10D ). The illustrated embodiment additionally includes the intermediate position shown in  FIGS. 9B and 10C  as a third pre-determined axial position at which the instrument delivery tubes can be retained. 
     In a preferred insertion position, the curved or angled distal regions  66  have a position that minimizes the maximum lateral distance between them. Thus, in  FIG. 9A , the distal regions  66  are side by side and the curves of the distal regions  66  curve in parallel to one another. A similar arrangement is seen with the alternative instrument delivery tube shape shown in  FIG. 10A . In the fully open or deployed position shown in  FIGS. 1 and 10D , the curved or angled distal regions  66  are widely spaced apart. In this position, the lateral distance between the rigid sections of the instrument tubes in a direction orthogonal to the longitudinal axis of the main tube is at its maximum, and may be longer than the diameter of the main tube  12 . In this position, the distal regions  66  of the two instrument delivery tubes  16  may share a common plane. For example, when viewed along the longitudinal axis of the main tube  12 , the curved distal regions  66  may extend to 3 o&#39;clock and 9 o&#39;clock positions. 
     The third axial position ( FIG. 9C ) is an intermediate position in which the curved or angled distal regions are separated by an amount less than in the fully deployed position. In this position, the curved distal regions  66  of the two instrument delivery tubes  16 , when viewed along the longitudinal axis of the main tube  12 , may extend in the 2 and 9 o&#39;clock positions, or in the 1 and 11 o&#39;clock positions, for example. Although the illustrated system has three predetermined axial positions for each instrument delivery tubes, alternative systems may have only two predetermined axial positions, or they may have four or more such positions. 
     The system includes features allowing the user to retain the position of the instrument delivery tube at the selected axial or longitudinal position. In some embodiments, each instrument delivery tube  16  and/or its associated actuator  22  includes a member positionable in engagement with the proximal fitting  48  in order to fix the position of the instrument delivery tube  16  relative to the main tube  12 . In the illustrated embodiment, this member takes the form of a coupling member  36  ( FIG. 6A ) insertable into a select one of the longitudinal channels  62   a - c  ( FIG. 5 ) of the proximal fitting. Referring to  FIG. 7A , a catch  38  is positioned at the distal end of the coupling member  36 . The catch  38  extends laterally from a longitudinally extending spring element  39 . The spring element  39  outwardly biases the catch  38  towards the adjacent circumferential grooves  64   a - d.  In the illustrated embodiment, the spring element  39  is defined by a longitudinal slot  41  in the coupling member  36 . 
     When the catch  38  is disposed within a circumferential groove of a corresponding channel, such as groove  64   c  of channel  62   c  as in  FIG. 7A , the spring bias of the catch  38  biases the catch into the groove and thus temporarily fixes the longitudinal position of the instrument delivery tube relative to the main tube  12 . When the member  36  is advanced or retracted within the channel, the spring element  39  is caused to deflect as shown in  FIG. 7B  in response to contact between the catch  38  and the material between the circumferential grooves  64   c ,  64   b , thus allowing the catch  38  to disengage from the groove  64   c . Positioning the catch  38  in alignment with a selected one of the other grooves will cause the catch  38  to spring outwardly into engagement with the selected groove, again temporarily fixing the instrument delivery tube at a second longitudinal position. 
     Each instrument delivery tube  16  is disposed in the main tube  12  with a portion of its straight section within the main tube  12  and with its curved or angled region  66  position distally of the main tube  12 . Before the system is introduced into a body cavity, the coupling member  36  is preferably coupled to the proximal fitting  48 . More specifically, the coupling member  36  is inserted into whichever of the longitudinal channels  62   a ,  62   b ,  62   c  corresponds to the desired axial orientation for the instrument delivery tube. For most applications, the coupling elements  36  for both instrument delivery tubes will be inserted into longitudinal channels  62   a , as shown in  FIG. 8A , in preparation for insertion of the system into the body cavity. This arrangement positions the curved distal regions of the instrument delivery tubes as shown in  FIG. 9A  or  10 A, thus placing their distal portions in a streamlined arrangement for easy insertion into the body. 
     The user may also pre-select a longitudinal position for the instrument delivery tube  16  by advancing the catch  38  into engagement with a select one of the circumferential channels  64   a - 64   d  as discussed above with reference to  FIGS. 7A and 7B . In doing so, the user is selecting how much of the distal end of the instrument delivery tube will extend from the main tube  12 . Selecting the most proximal channel  64   a  will cause the shortest length of instrument delivery tube  16  to extend from the main tube  12 , whereas selecting distal-most channel  64   d  will cause the longest length of instrument delivery tube  16  to extend from the main tube  12 . If the user wishes to change the longitudinal position of an instrument delivery tube  16  during a procedure, s/he may do so by advancing or retracting it to the desired position and causing the catch  38  to engage the adjacent circumferential groove as discussed in connection with  FIGS. 7A and 7B . 
     During the course of a procedure, the user may also choose to change the axial rotation of a given instrument delivery tube. For example, after the system has been inserted into to the body, the user may choose to rotate at least one of the instrument delivery tubes out of the position shown in  FIG. 9A  and into the position shown in  FIG. 9B  or  FIG. 1 . 
     To make this adjustment, the user extracts the coupling member  36  from a first one of the longitudinal channels  62   a ,  62   b ,  62   c  and re-inserts the coupling member  36  into a selected second one of the longitudinal channels corresponding to the desired axial position. Once the coupling member  36  is in the desired longitudinal channel, it is advanced until the catch  38  engages with the circumferential groove corresponding to the desired longitudinal placement of the instrument delivery tube  16 . Inserting the coupling members  36  into channels  62   b  as shown in  FIG. 8B  will position the instrument delivery tubes in the positions illustrated in  FIG. 9B  or  10 C. Inserting the coupling members  36  into channels  62   c  as shown in  FIG. 8C  will position the instrument delivery tubes in the positions shown in  FIG. 1  or  10 D. While these figures show the two instrument delivery tubes at the same axial and longitudinal positions, it is important to note that the instrument delivery tubes are independently adjustable both axially and longitudinally. Thus, each instrument delivery tube may be placed at a different axial and/or longitudinal position from that of the other instrument delivery. 
     In the illustrated embodiment, the longitudinal channels and circumferential slots enable the instrument delivery tubes  16  to be axially rotated between discrete axial positions and, once in a chosen axial orientation, to be longitudinally advanced/retracted between discrete longitudinal positions relative to the proximal fitting. Alternate embodiments might, however, be configured to allow axial rotation of an instrument delivery tube without altering the longitudinal position. Embodiments of this type will be described in connection with the third and fourth embodiments. 
       FIG. 11A  shows a cross-section view of the proximal end of one of the instrument delivery tubes  16  and the corresponding actuator assembly  22 . In general, the actuator assembly  22  includes a distal element  82 , a proximal element  94 , and a spring  96  extending between the distal and proximal elements. The rigid control tube  24  is coupled to the proximal element  94 . The control tube  24  includes a lumen for receiving a medical instrument that is to be deployed through a corresponding instrument delivery tube  16 . The control tube  24  may have a lubricious lining formed of PTFE or other suitable material so as to allow instruments inserted through the control tube to slide with ease. 
     Distal element  82  is mounted to the proximal end of the rigid tube  18  of the instrument delivery tube  16 . The distal element includes a lumen  83 . The proximal end of the rigid tube  18  is disposed in a fixed position within the lumen  83 , with the proximal end  78  of the flexible inner tube  20  extending further proximally within the lumen  83 . A plurality of openings or slots  84  (one visible in  FIG. 11A ) is formed in the distal element  82 . Each slot  84  extends from the lumen  83  to the exterior of the distal element  82 . 
     In a proximal portion of the distal element  82 , the lumen  83  is surrounded by an inner cylindrical wall  86 , which is itself surrounded by an outer cylindrical wall  88 . The outer wall  88  defines a proximally facing cylindrical interior or receptacle, and also defines a cylindrical gap  92  between the two walls  86 ,  88 . As best seen in  FIG. 6A , a plurality of through holes  90  extend from the proximal end of the gap  92  ( FIG. 11A ) to the exterior of the proximal fitting  82 . The through holes  90  and the slots  84  are radially aligned and correspond in number to the number of pullwires in the corresponding instrument delivery tube  16 . 
     Referring again to  FIG. 11A , proximal element  94  includes a wall  106  defining a distally-facing cylindrical interior or receptacle  108 . A lumen  110  extends from the interior  108  to the proximal face of the proximal element  94 . A plurality of pullwire lumen  112  extend through the proximal element  94 , preferably in parallel to the lumen  110 . 
     The spring  96  is coupled between the proximal element  94  and the distal element  82 . In the illustrated embodiment, the distal end of the spring is disposed in the proximally-facing receptacle defined by outer wall  88  of the distal element  82 , and the proximal end of the spring is disposed in the distally-facing receptacle  108  of the proximal element  94 . 
     The spring  96  is a rigid spring formed of stainless steel or other suitable materials. Components extending through the spring define a sealed instrument passage between the proximal and distal elements  94 ,  82 . A seal, such as the cross-slit seal  100  shown in  FIG. 11A , is positioned in the lumen  83 . This seal prevents loss of insufflation pressure through the actuator assembly  22  during times when there is not an instrument disposed in the corresponding instrument delivery tube. A length of flexible tubing, such as a Tygon tube  102 , extends proximally from the seal  94 . A connector  104  couples, and creates a seal between, the inner wall  86  and the tube  102 . 
     The proximal end of the tube  102  extends into the lumen  110  of the proximal element  94 . A tubular coupling  114  forms a sealed connection between the tube  102  and the control tube  24 , which has a distal end disposed within the lumen  110 . A seal  116  is positioned on the proximal end of the control tube  24 . Seal  116  is preferably an elastomeric septum-type seal having an opening proportioned to seal against the shaft on an instrument positioned through the control tube  24 . 
     The mechanism by which the actuator assemblies  22  control deflection of the flexible distal region of the corresponding instrument delivery tube will be next be described. As discussed in connection with  FIG. 6B , pullwires  80  are anchored within the deflectable distal portion  76  of each flexible tube  20 , and extend from the proximal portion  78  of the flexible tube  20  which, as noted in the discussion of  FIG. 11B , is disposed within the distal element  82  of the actuator  22 . The pullwires  80  then extend from the distal element  82  and are anchored to the proximal element  94 . While other arrangements can be used, in the arrangement illustrated in  FIG. 11 , the pullwires  80  extend from the flexible tube  20 , exit the distal element  82  via the slots  84 , re-enter the distal element  82  via the throughholes  90 , and extend through the spring  96  into the proximal element  94 . The pullwires  80  are coupled to adjustment screws  118  on the proximal element  94 . The adjustment screws are rotatable to adjust the sensitivity of the actuator by increasing or decreasing the tension on the pullwires. 
     Some prior art surgical access systems allow for pivotal motion of the shafts of instruments or instrument delivery cannulas relative to the longitudinal axis of the access port disposed within the incision, creating a fulcrum at some point along the shaft of the instrument. In preferred embodiments it is desirable to provide the access system with features that restrain the shafts of the instrument delivery tubes  16  against pivotable movement relative to the main tube  12 , instead retaining the shafts of the instrument delivery tube such that the angular orientation of each instrument delivery tube remains fixed relative to the longitudinal axis of the main tube or base  12 . With this arrangement, the straight proximal sections  70  of the instrument delivery tubes remain in parallel to one another and the curved section  68  of the rigid tubes are prevented from pivoting within the body. Thus, movement at the distal regions  66  of the instrument delivery tubes is limited to deflection of the flexible tube  20 , axial rotation as described with reference to  FIGS. 8A-8C , and longitudinal movement as described with reference to  FIGS. 7A and 7B . 
     In the first embodiment, restraint against pivotable movement of the instrument delivery tubes  16  is provided by the connection between the proximal fitting  48  and the coupling members  36 , and/or by the elongate bores  56  in the base  52  of the proximal fitting, and/or by the walls of the main tube  12  and/or the openings  30  in the partition  14 . 
     To use the system, an incision is formed through the skin and underlying tissue. The distal end of the main tube  12  is inserted through the incision and into the body cavity. For the insertion step, the instrument delivery tubes  16  are preferably positioned as shown in  FIGS. 9A and 10A  for ease of insertion. The body cavity is inflated using a source of inflation gas as is common in laparoscopy. An insufflation port may be provided in one of the instrument delivery tubes or ports  26 ,  28  or elsewhere in the device to allow a source of gas to be coupled to the access device for use in inflating the body cavity. As discussed, seals are provided for each port  16 ,  26 ,  28  to seal the ports against loss of inflation pressure around the shafts of instruments positioned in the ports, as well as to minimize loss of inflation through ports not occupied by instruments at any given time. 
     The surgeon will select instruments needed to perform a procedure within the body cavity. For example, referring to  FIG. 12 , a first instrument  120  is chosen through deployment and use through a first one of the instrument delivery tubes  16 , and a second instrument (not shown) is selected for use through a second one of the instrument delivery tubes. A third instrument  122 , which may be one with a rigid shaft, is positioned through the port  26 , with its distal end passing into the body cavity through opening  32  in the partition  14 . A fourth instrument  124  (e.g. a rigid endoscope) is advanced into the body cavity through port  28  and opening  34 . 
     To deploy an instrument through an instrument delivery tube  16 , the distal end of the instrument I is inserted into to the port  116  at the proximal end of the control tube  24 . The instrument is advanced to pass the distal end through the actuator  22  and through the instrument delivery tube  16  until it extends from the distal end of the flexible tube  20 . The instrument  120  may then be use for diagnosis or treatment at a treatment site in the body cavity. 
     When it becomes necessary for the surgeon to deflect or articulate the distal end of the instrument  120 , s/he intuitively moves the handle of that instrument, causing the control tube  24  and thus the proximal element  94  to move with it. The instrument  120  may be provided with a rigid section  126  extending from the handle to optimize force transfer from the instrument  120  to the control tube  24 . Movement of the control tube will cause the proximal element  94  of the actuator  22  to move relative to the distal element  82 , causing the spring  96  to bend and tensioning the pullwires in accordance with the angle of the proximal element relative to the distal element. The pullwires deflect the distal portion  76  of the flexible tube  20  portion of the instrument delivery tube  16 , causing corresponding deflection of the distal end of the shaft of the instrument disposed within the instrument delivery tube. Thus, to lower the distal end of the instrument as shown in  FIG. 12B , the user will raise the instrument handle  120 , moving the proximal portion  94  upwardly relative to the distal portion  82 . This will thus apply tension to the lower pullwires, causing downward deflection of the instrument delivery tube as well as the distal end of the instrument. Lateral movement of the instrument shaft to the right will tension the corresponding side pullwire to cause the distal portion of the instrument delivery tube to bend to the left. The actuator system allows combinations of vertical and lateral deflection, giving 360° deflection to the instrument delivery tube. The user may additionally advance/retract the tool longitudinally within the instrument delivery tube, and/or axially rotate the instrument within the instrument delivery tube when required. 
     Instruments suitable for use with the instrument delivery tubes include those described in co-pending U.S. application Ser. No. ______, filed Jul. 28, 2009, (Attorney Docket No. TRX-2100), entitled Flexible Dissecting Forceps, and U.S. application Ser. No. ______, filed Jul. 28, 2009, (Attorney Docket No. TRX-2400), entitled Flexible Medical Instruments, each of which is incorporated herein by reference. 
     It should be noted that the deflectable instrument delivery tubes and actuators described in connection with  FIGS. 10-12B  may be used with any other type of access system suitable for use in giving access to a body cavity. For example, the instrument delivery tubes and actuators may be used in trocars or other laparoscopic ports or access devices now known or developed in the future. Moreover, the instrument delivery tubes may be provided with alternative actuation systems for the pullwire. Various pullwire actuation systems are known to those skilled in the art and may be adapted for use with the instrument delivery tubes  16 . 
       FIG. 13  shows the proximal portion of an instrument delivery tube  16  equipped with one type of alternative actuator  22   a . In this embodiment, the features of the instrument delivery tube  16  are similar to those described earlier and thus will not be repeated. Details of the actuator  22   a  are most easily seen in the exploded view of  FIG. 14 . The actuator  22   a  includes a control tube  24   a  having proximal entry port/lead seal  116   a  for receiving a medical instrument that is to be deployed through the instrument delivery tube  16   a . A proximal gimbal portion  128  is positioned distally of the control tube  24   a  and includes a proximal opening  130  which receives the distal end of the tube  24   a . The proximal gimbal portion  128  also includes a distally facing socket  132 . A distal gimbal portion  134  includes a proximally facing ball  136  disposed within the socket  132  and a tubular housing  138  extending distally from the ball  136 . The ball  136  has a proximally-facing opening  142 . A valve  144 , which may be a cross-slit duck bill valve, is disposed within the tubular housing  138 . The valve  144  functions to seal the actuator against loss of inflation pressure when no instruments are positioned through it. 
     A fitting  146  ( FIG. 13 ) connects the instrument delivery tube  16   a  to the proximal gimbal section  134 . Pullwires  80  exiting the proximal end of the instrument delivery tube  16  exit the distal gimbal section  138  through slots  148  and into engagement with the proximal gimbal section  128 . The pullwires are coupled to the proximal gimbal section  128  and secured using nuts  118  in a manner similar to that described with the first embodiment. In a slight modification to the  FIG. 13  embodiment, nuts  118   a  are replaced by ball pivot mounts  118   a  as shown in  FIG. 21  to create a universal joint for each pullwire. Each pullwire  80  is attached by a tensioning nut housing  119  to a ring  121  that encircles the corresponding ball pivot mount  118   a  and that has full freedom to move in any direction over the surface of the ball pivot. 
     Referring again to  FIG. 15 , a Tygon tube (not shown) may extend through the actuator, coupled to the control tube  24   a  and the instrument delivery tube  16   a  in a manner similar to that described in connection with  FIG. 10  to maintain a sealed lumen from the proximal end of the control tube  24   a  to the distal end of the instrument delivery tube  16   a.    
     During use of the actuation system, the shaft of an instrument (e.g. instrument  120  shown in  FIG. 12A  is inserted through the control tube  24   a  ( FIG. 13 ), proximal gimbal portion  132 , distal gimbal  134  portion etc. and through the instrument delivery tube  16   a  such that its operative end exits into the body cavity. To deflect the distal end of the instrument, the user moves the handle of that instrument, causing the control tube  24   a  to move with it. The socket of proximal gimbal portion  128  will move over the ball surface of the distal gimbal portion  134 , thus tensioning the pullwires in accordance with the angle of the proximal gimbal portion relative to the distal gimbal portion. The distal portion of the instrument will deflect accordingly as a result of the action of the gimbal on the pullwires of the instrument delivery tube. 
     Referring again to  FIG. 1 , the access system includes a mount  150  allowing the system to be engaged by a clamp on a supportive arm for supporting the system  10  without requiring the system  10  to be held in place by operating room personnel. In the illustrated embodiment, the mount  150  includes a collar  152  disposed on the proximal fitting  48  or tube  12  and an arm  154  extending from the collar  152 . An adjustment screw  156  allows the grip of the collar on the tube  12  to be tightened or loosed. A spherical coupling  158  is disposed on the arm  154 . The spherical coupling  158  is shaped to be received and engaged by a connector  160  provided on an arm  161  mounted to the operating table (not shown) or to another operating room fixture such as the ceiling or a cart. 
     The illustrated clamp  160  comprises a collar having semi-annular segments  162 . Each segment  162  includes a first end  164  coupled to the other one of the segments, and a second end  166  hinged to a latch  168 . The collar has an unlatched position shown in  FIG. 1  in which the latch  168  is pivoted outwardly to separate the ends  166  of the semi-annular segments  162 . The latch is inwardly pivotable to place the collar in a latched position, in which the ends  166  are drawn closer together and retained in the closed position by the latch  168 . 
     To couple the spherical coupling  158  to the clamp  160 , the clamp is placed in the unlatched position and disposed around the mount  158 . The user places the system  10  in the desired three-dimensional orientation and then closes the latch  168  to capture the spherical mount  158  between the segments  162 . 
     If the tube  12  needs to be rotated around its longitudinal axis during a procedure or preparation for a procedure in order to collectively adjust the positions of the instrument delivery tubes and passive tubes, the collar  152  of the mount  50  is loosened, the tube  12  is axially rotated, and the collar is retightened. 
       FIG. 15  shows a second embodiment of a multi-instrument access device  200 . The access device  200  includes a base  212  positionable within an opening (e.g. an incision or puncture) formed in a body wall, through the umbilicus or elsewhere. An upper housing or seal  214  is attachable to the base  212  and positioned such that it is disposed outside the body wall during use.  FIG. 17  schematically illustrates the base  212  in an incision in a body wall. 
     Referring to  FIG. 18 , base  212  is a generally hollow or tubular member having a wall  225  defining a lumen  218  and a distal flange  216  surrounding the distal opening of the lumen. The flange and distal opening may be circular, elliptical, or any other shape suitable for insertion into an opening in the body wall. The base  212  is preferably constructed of a flexible material that allows the base  212  to be pinched or flattened into a smaller profile for insertion through the opening in the body wall, and that will preferably restore the base to its original shape and size after compression is released. 
     Flange  216  has a width that will define a sufficient margin around the border of the opening in the abdominal wall to prevent its inadvertent withdrawal from the opening during use. Although flange  216  is shown as a fully circumferential member, alternate elements that are not fully circumferential (e.g. two or more flange segments), may alternatively be used to perform the same retention function. By including a broad flange, the base is able to retract peritoneal tissue away from the base port, keeping the tissue from obstructing access, preventing tools and/or implants from inadvertently slipping between the abdominal wall and the peritoneal tissue. The flange  216  may also form a seal around the incision to help maintain insufflation pressure within the abdominal cavity. 
     The base  212  and upper housing/seal  214  are preferably separate pieces attachable to each other during use. The seal  214  includes a first engaging portion which in this embodiment takes the form of a flange  226 . The base  212  includes a second engaging portion positioned to engage the first engaging portion. In the illustrated embodiment, the second engaging portion includes a ring  228  on the base  212 . The flange  226  of the seal  214  seats against and makes sealing contact with the ring  228 . Clips  232  (preferably two or more) on the ring  228  are used to secure the base  212  to the seal  214 . 
     The base  212  may be placed in the opening in the body wall before the seal  214  is coupled to the base. This is particularly beneficial where an initial step in the procedure may involve an instrument or implant that is too large for the ports  220 . For example, where the access device  200  is to be used to implant a lap band or a Swiss lap band of the type used to induce weight loss, the lap band may be dropped through the lumen  218  in the base  212  and into the operative space. Then, once the seal  214  has been coupled to the base  212 , the implant may be retrieved from within the operative space using an instrument passed through the seal  214 . To position the flexible base  212  in the incision, it is folded or pinched and inserted into the opening O in the abdominal wall W and advanced until distal flange  216  is disposed beneath the abdominal wall W. The base  212  is allowed to unfold such that the wall surrounding the base contacts the edges of the opening O, keeping the opening open for access by instruments. 
     As shown in  FIG. 17 , a proximal flange  224  (or equivalent structure) is positioned to contact the skin surrounding the opening in the abdominal wall, to prevent the access device from inadvertently being pushed into the body cavity during use. This structure may be provided on the distal portion of the seal  214  or on the proximal portion of the base  212 . 
     Referring again to  FIG. 15 , seal  214  includes a plurality of ports  220   a ,  220   b  extending proximally from the base  212 . The ports  220   a , b are tubular elements having proximal openings  222 . The ports  220   a ,  220   b  are configured to receive instruments for use in performing a procedure within the body cavity. Valves (not shown in  FIG. 15 ) are positioned within the ports  220   a ,  220   b  so as to maintain insufflation pressure within the abdominal cavity during use of the access device  200 . These valves may include a duckbill valve for preventing loss of pressure when no instruments are disposed in the ports  220   a ,  220   b  as well as annular seals or septum seals for sealing against the shafts of instruments passed through the ports  220   a ,  220   b . The ports  220   a ,  220   b  may be flexible to allow them to pivot relative to the base  212  when instruments deployed through them are being used in the body cavity. 
     The other two ports  220   c  are provided to have instrument tubes  16   b  extending through them or coupled to them. The ports  220   c  may comprise passages through the upper housing, such as openings into the interior of the seal  214 . Each instrument tube  16   b  extends through a port  220   c  and through the seal and base, and extends out the distal opening in the base. Each instrument tube  16   b  is provided with a pre-shaped curve in its distal region  252 . The instrument tubes have a closed position shown in  FIG. 15  in which the distal regions  252  are positioned to minimize the lateral distance between them. In the closed position, the distal regions  252  may cross as shown. The instruments tubes further have an open or deployed position shown in  FIG. 16  in which the curved distal regions are oriented such that instruments passed through the lumens of the instrument tubes can access a target treatment site. In this position, the longest lateral distance between the instrument tubes may be longer than the diameter of the wall of the base. 
     In one configuration, each instrument tube  16   b  includes a rigid stiffener tube  254  having the pre-shaped curve. The rigid tubes may all have the same size and/or geometry, or two or more different sizes and/or geometries may be used. The curve in any given instrument tube may be continuous or compound, and it can be formed to occupy a single plane or multiple planes. 
     In one embodiment shown in  FIG. 21 , each rigid tube  254  has a generally straight main section  255   a , and a pre-shaped curve  255   b  that generally curves outwardly from the main section  255   a  and that then (optionally) curves slightly inwardly. The curve(s) of the distal section may lie within the plane containing the main section  255   a  as shown, or the curve(s) may exit that plane. The curvature of the rigid stiffener tubes  254  serves to orient the distal sections  252  towards one another such that instruments passed through the instrument delivery tubes  16   b  can access a common treatment site when the instrument delivery tubes  16   b  are in the deployed position. The rigid stiffener tubes may be formed of stainless steel or other rigid tubing. 
     Flexible inner tubes  257  extend through the rigid stiffener tubes  254 . Each inner tube  257  has a distal section  257   a  that extends distally from the corresponding rigid tube, and a proximal section  257   b  that extends proximally from the corresponding rigid tube. The inner tubes  212  can be made with or without a pre-formed shape. 
     Each inner tube  257  includes a lumen for receiving an instrument that is to be used within the body. Also provided on each inner tube is a plurality of pull wires  276  extending through pullwire lumens and anchored near the distal end of the inner tube  257 . In the preferred embodiment, each instrument delivery tube has four wires such arranged at 90 degree intervals. Other embodiments can utilize different numbers of pullwires, such as three pullwires equally spaced around each inner tube  257 . 
     The set of pullwires for each of the inner tubes  257  is coupled to a corresponding actuator  259 , which may be manipulated to deflect the distal sections  257   a  of the flexible tubes  257  as discussed in connection with the first embodiment. The actuators  259  may be similar to the actuators described with reference to  FIG. 11  or  14 , or alternative actuators may be used. By deflecting the distal sections of the instrument delivery tubes  257 , the flexible instruments extending through them are deflected within the body into desired positions and orientations. 
     The rigid tubes of the instrument delivery tubes  16   b  are axially rotatable to a closed or insertion position, shown in  FIG. 15 , in which the instrument tubes have a more streamlined orientation for passage through the incision during insertion and withdrawal of the access system. Various mechanisms may be used for axially rotating the instrument tubes. In the embodiment illustrated in  FIGS. 15-21 , the rigid tubes  254  of the instrument delivery tubes are mounted at their proximal ends to gear members  278  or to bushings  277  attached to the gear members. The gear members  278  have teeth at their outer periphery. A rotatable collar  261  which has teeth along its inner periphery is positioned surrounding the gear members, such that teeth of the gear members  278  mesh with teeth of the rotatable collar  261 . With this arrangement, rotation of the collar will cause simultaneous rotation of the rigid tubes  254  and thus the instrument delivery tubes  16   b  between the deployed and the insertion positions. The connection between the gear members or bushings and the rigid tube prevent pivotable movement of the rigid tubes relative to the base. 
     Referring to  FIG. 20 , the outer circumference of the collar  261  is exposed through a slot  279  in the upper housing  214  to permit a user to rotate the collar  261  relative to the upper housing  214 . Support members connecting the portion of the upper housing disposed above the slot to the portion of the housing below the slot are not visible in the drawings. In an alternative embodiment, the collar  261  may be positioned between the upper housing  214  and the base  216 . In either case, seals may be positioned above and below the collar to minimize loss of insufflation pressure between the collar and the upper housing and/or base. 
     A plate  280  may be positioned beneath the gear members and the collar  261  so as to support the collar. In one embodiment, the plate may be arranged to seat within the proximal end of the base  212 , such as on the ledge  229  within the proximal opening of the base shown in  FIG. 18 . Alternatively, the plate may be mounted within the distal portion of the upper housing or seal  214 . Holes  281  are arranged on the plate to receive the stiffener tubes  254 , and holes  282  are similarly positioned to receive instruments inserted through the ports  220   a ,  220   b . As with the first embodiment, the rigid tubes  254  of the instrument delivery tubes in the second embodiment are mounted to the system in a manner that prevents them from pivoting relative to the housing  212 ,  214 . In this embodiment, restriction against pivoting is provided by the connection between the proximal ends of the rigid tubes and the gear members  278 . 
     The second embodiment preferably includes a mount (not shown) such as the mount  150  of  FIG. 1  allowing the system to be engaged by a clamp on a supportive arm attached to an operating table, ceiling mount, side cart, or other structure. 
     A third embodiment is shown in  FIGS. 22 through 29  and has many features similar to those shown in the  FIG. 15-21  embodiment. However the  FIG. 22-29  embodiment, includes a different mechanism for axially rotating the instrument delivery tubes and it has an alternative upper housing configuration. 
     Referring to  FIG. 22 , the system  310  of the third embodiment includes a base  312  and an upper housing  314 . The features of the base  312  may be similar to those described in connection with the first embodiment, as shown in  FIGS. 23 and 24 . 
     The proximal section of each rigid tube  354  is moveably coupled to the upper housing  314 . As with the first and second embodiments, active ports in the form of deflectable instrument delivery tubes  16   b  are supported by the upper housing  314 . The instrument delivery tubes  16   b  and associated actuators share many features with those of the first embodiment, including rigid tubes  354  and flexible tubes  357  extending through the rigid tubes  354 . However, in the instrument delivery tubes of the second embodiment, the rigid tubes  354  extend fully to the actuator rather than leaving an exposed portion of the flexible tube  357  as was shown in  FIG. 21 . 
     Referring to  FIG. 26 , the upper housing  314  includes a lower plate section  328  having individual or interconnecting openings  330 . The instrument delivery tubes  16   b  extend through of the openings  330 . Rigid, proximally-extending support members  332  extend from the lower plate section as shown. The members  332  are shaped to receive and rigidly support the proximal portions of the rigid tubes as shown in  FIG. 28 , and to prevent pivotal movement of the rigid tubes  354 . The members may be tubular, or they might have a partially tubular or open construction as shown. In the illustrated embodiment, each member  332  includes an opening  334  through which an instrument delivery tube may be inserted. Each member includes an inner surface having a guide slot  336  with a longitudinal portion  338  and a circumferential portion  340 . 
     A bushing  342  mounted to the shaft of each stiffening tube  354  includes a protrusion  346  that extends into the L-shaped slot  336 . The position of the protrusion relative to each stiffening tube is such that when the stiffening tubes are in the closed position (as in  FIG. 15A ), the protrusion is positioned within the circumferential portion of the guide slot  336 , away from the longitudinal portion. To axially rotate the instrument delivery tubes to the deployed positions, the user will rotate the rigid tubes  354 , causing them to axially rotate. When the rigid tubes have been rotated sufficiently to position the protrusion of the bushing into alignment with the longitudinal portion of the guide slot the instrument delivery tubes may be longitudinally advanced further into the body if desired. The longitudinal position of the instrument delivery tubes may be altered during the course of the procedure in this manner. 
     A pair of tubular ports  320   a ,  320   b  extend from the upper housing section  314  and through two of the openings  330  in the lower plate section  328 . The ports  320   a ,  320   b  are passive ports for receiving instruments to be inserted into the body cavity. These ports may take the form of detachable ports each of which might have a duckbill valve and annular instrument seal similar to those described above in connection with the second embodiment. The ports  320   a ,  320   b  may be of equal size, or the sizes may differ between the ports. 
     Referring to  FIG. 25 , the distal end of each port  320   a ,  320   b  includes a circumferential groove  318  proximally offset from the distal end of the port. A plate  324  disposed within the system, such as on the ledge  329  discussed in the first embodiment ( FIG. 18 ), includes openings  326  for receiving the ports. To mount a port  320   a  to the plate, the distal end of the port is inserted into one of the openings. The port is pressed downwardly to cause groove  318  to contact the portion of the wall surrounding the opening in the plate, thereby forming a seal around the opening. It should be noted that the other openings  328  in the plate are positioned so that the instrument delivery tubes may extend through them. 
     Referring to  FIGS. 23 and 24 , the spherical mount  160  is positioned on a collar that is rotatably positioned on the base or upper housing, allowing the entire system to be axially rotated relative to the mount if repositioning is needed. 
     A fourth embodiment of an access system  400  is shown in  FIG. 30 . The access system  400  is similar to that of the third embodiment in that it is designed to restrict or prevent longitudinal movement of the instrument delivery tubes when they are in the closed position (e.g. similar to that shown in  FIG. 9A ), and to allow longitudinal movement once the instrument delivery tubes have been axially rotated into the deployed position such as that shown in  FIG. 30 . As with the first through third embodiments, the instrument delivery tubes are restricted against pivotal movement relative to the main access cannula or base. 
     System  400  includes a proximal housing  402  which may be coupled or attachable to a distal housing or cannula positionable in an incision. The distal housing may be similar to that of any of the previously described embodiments (e.g. main tube  12  of  FIG. 1  or base  212  of  FIG. 15 ). 
     Referring to  FIG. 31 , the proximal housing  402  includes a proximal surface  404 . A pair of bores  406  extend through the housing  402  from the proximal surface  404 . The bores  406  function as access ports for instruments to be used in the body cavity. 
     As shown in  FIG. 31B , each bore includes a valve  408  such as a cross-slit or duck bill valve recessed below the surface  404 . The valves  408  function to seal the bores during times when the bores are not occupied by instruments. Septum seals  410  are positioned proximal to the valves  408  and serve to seal against the shafts of instruments passed through the ports. 
     Two additional bores  412  extend through the proximal housing  402 . As shown in  FIG. 30 , instrument delivery tubes  16  are disposed in the bores  412 . The instrument delivery tubes  16  may be similar to those described in connection with the first, second and third embodiments, or alternate instrument delivery tubes may instead be used. 
     Posts  414  extend proximally from the surface  404 , in parallel to the instrument delivery tubes. Each post includes a distal section  415 , a reduced diameter section  416 , and a proximal head  418  that is broader than the reduced diameter section  416 . 
     Guides  420  are mounted to the shaft of each instrument delivery tube  16 . Each guide  420  includes a cutout  422  extending through the guide in the longitudinal direction. The cutout curves in parallel to the cylindrical outer surface of the instrument delivery tube. The cutout has a sort of “apostrophe” shape, with a main section  424  and an enlarged generally cylindrical section  426  is positioned at one end of the main section  424 . The radial width of the main section  424  is narrower than the diameter of the head  418  or the distal section  415  of the post  414 , whereas the enlarged section  426  is shaped and sized to allow the head  418  and distal section  415  to pass through. 
     As with the prior embodiments, the instrument delivery tubes  16  are axially rotatable. Axial rotation of the instrument delivery tubes  16  likewise rotates the guides  420 , thus changing their positions relative to the posts  414 . When an instrument delivery tube  16  is axially positioned such that the longitudinal axis of the guide&#39;s enlarged cutout section  426  is aligned with the longitudinal axis of the post  414  (see  FIG. 32A ), the distal portion  66  of the instrument delivery tube is in the fully deployed position shown in  FIG. 30 . When an instrument delivery tube is in the deployed position, the enlarged section  426  of the cutout in the guide  420  is axially aligned with the post  414 , allowing for longitudinal movement of the instrument delivery tube as illustrated in  FIG. 32C  since the enlarged section  426  is sufficiently large to slide over the head  418  and distal section  415  of the post  414 . 
     The instrument delivery tube  16  may be axially rotated towards the closed position when the reduced diameter section  416  of the post  414  is disposed within the cutout  422 . Axial rotation of the instrument delivery tube  16  such that the end of the cutout  424  opposite from the enlarged section  426  receives the post  414  as is shown in  FIG. 32B  places the distal portions  66  of the instrument delivery tubes in a closed position similar to that shown in  FIG. 9A . Note that when the longitudinal axis of the enlarged section of the cutout  426  is axially offset from the longitudinal axis of the post  414  as in  FIG. 32A , the head  418  and distal section  415  of the post  414  limit or prevent longitudinal movement of the instrument delivery tube since they cannot pass through the main section  424  of the cutout. Thus, in the preferred embodiment, when the instrument delivery tubes are in the closed position, they are restricted against longitudinal movement. 
     While certain embodiments have been described above, it should be understood that these embodiments are presented by way of example, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention. This is especially true in light of technology and terms within the relevant art(s) that may be later developed. 
     Any and all patents, patent applications and printed publications referred to above, including for purposes of priority, are incorporated herein by reference.