in the following detailed description of the preferred embodiments , reference is made to the accompanying drawings , which form a part hereof , and within which are shown by way of illustration specific embodiments by which the invention may be practiced . it is to be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the invention . referring to fig1 , there is shown a sagital view of a patient undergoing an endoscopic biopsy of the pineal gland , illustrating only one example in which the endsoscopic sheath and retractor 5 of the present invention might be utilized during endoscopic surgery . in the example shown , a extra - ventricular trajectory is taken . endosurgical port a is shown , through which endoscopic sheath 5 is inserted . this allows the surgeon to view the internal tissues and organs in the surgical area . sheath 5 of the present invention is inserted through the opening or port a made in the patient &# 39 ; s body . a pair of endosurgical forceps may be inserted through surgical port a to aid in the positioning of the endoscopic sheath 5 . as illustrated in fig1 - 3 , the inflatable retractor 10 of sheath 5 is used to constrain and retract the cerebrum and cerebellum to permit endosurgical access to the pineal region . it should be noted , however , that the principles of the present invention are not limited to any particular surgical procedure but may be applied to a wide variety of procedures and applications , including direct surgery . referring now to fig2 - 4 , there is shown one embodiment of endoscopic sheath 5 with inflatable retractor 10 of the present invention . fig2 illustrates retractor 10 mounted on outer cannula 20 suitable for use in endoscopic procedures . the length of outer cannula 20 is primarily dependent upon the type of procedure in which the retractor is to be used . inner cannula 25 has a proximal or control end 25 b , and a distal or insertion end 25 a . both outer cannula 20 and inner cannula 25 are preferably made of a material which will remain free from degradation , are easily sterilized , and are biocompatible . the shape of the distal or insertion end 25 a is chosen to aid in preventing the puncture or other injury to internal organs and tissue when sheath 5 is being manipulated inside the patient &# 39 ; s body . proximal end 25 b remains outside the patient &# 39 ; s body during the procedure . suspension strands 40 connect inner cannula 25 to outer cannula 20 , thereby allowing the movement of inner cannula 25 in three axis once outer cannula 20 is secured . suspension strands 40 are preferably adapted to return inner cannula 25 to a home position , substantially parallel to outer cannula 20 , when no force is applied to inner cannula 25 . this arrangement allows inner cannula 25 to be freely moveable thereby enabling manipulation of the endoscopic device away from delicate structures . in addition to the cannula - housing shown in fig2 - 4 , the present invention is also compatible with standard trocar - induced cannulas frequently utilized in endoscopic surgery . as such , the cannulas provide a port into the patient &# 39 ; s body and a short tube for the insertion of endoscopic instruments . thus , the principles of the present invention are not to be limited to any particular housing , cannula , or method of insertion into the patient &# 39 ; s body . still referring to fig2 , the inflatable retractor 10 consists of a long , inflatable balloon or membrane with an anatomical configuration designed to retract structures specific to the surgical procedure . the membrane of retractor 10 is comprised of a soft , flexible material which preferably does not absorb liquid and is easily sterilized , such as silastic , rubber , vinyl , polyethylene , or other polymeric material . a small - diameter hollow tube made of non - collapsible , flexible material which is connected to the membrane of retractor 10 at its proximal end . this hollow tube permits the entry and exit of gas or liquid to and from the inflatable membrane . the proximal end of the tube connects to an inflation and venting device ( not shown ). this device can be any of a variety of devices , including , for example , a bulb - type or piston - type syringe , a gas cartridge , or a fluid pump . the operation of the inflatable endoscopic retractor as used in a biopsy of a pineal - region tumor will now be explained , as illustrated in fig2 through 4 . the body is first prepared by creating a burr - hole within the skull of the patient . endoscopic sheath 5 is inserted into the patient &# 39 ; s body through the burr - hole in the selected trajectory . the trajectory may be a natural anatomical compartment , for example : csf cisterns in closed procedures , or through brain tissue in open transventricular procedures . in this example , trocar 100 is positioned within inner cannula 25 prior to insertion . an endoscope ( not shown ) may also be inserted into the body to aid in visualizing the internal structures and to ensure the proper positioning . for example , a pair of forceps suitable for use in endoscopic surgery may be inserted to aid in the positioning of the sheath 5 . trocar 100 is removed leaving inner cannula 25 free for insertion of an endoscope , for example . distal end 25 a of inner cannula 25 can be placed in optimum position under vision by the endoscope . in this example , trocar 100 is positioned within inner cannula 25 prior to insertion . an endoscope ( not shown ) may also be inserted into the body to aid in visualizing the internal structures and to ensure the proper positioning . a pair of forceps 70 suitable for use in endoscopic surgery may be inserted to aid in the positioning of the sheath 5 . trocar 100 is removed leaving inner cannula 25 free for insertion of an endoscope , for example . distal end 25 a of inner cannula 20 can be placed in optimum position under vision by the endoscope . as illustrated in fig3 , retractor 10 is mounted to outer cannula 20 and positioned , under direct view or with the help of an endoscope , within the patient &# 39 ; s body . the membrane of retractor 10 may be slightly inflated to aid in its maneuvering . retractor 10 can now be inflated against the surrounding neurovascular structure to reposition them away from endoscopic manipulations . with retractor 10 inflated and distal end 25 a of inner cannula 25 positioned near the structure of interest , here the pineal region tumor , the endoscopic procedure can be performed while protecting the surrounding neurovascular structures . retractor 10 is deflated , and the endoscope and sheath 5 are safely removed when the procedure is completed . furthermore , the endoscopic sheath of the present invention provides for inspection of the working trajectory as the endoscopic devices are removed . it will be seen that the objects set forth above , and those made apparent from the foregoing description , are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention , it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense . it is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described , and all statements of the scope of the invention which , as a matter of language , might be said to fall therebetween . now that the invention has been described ,
an endoscopic sheath having a biomimetic retractor for retracting organs and tissues in the body . the inflatable retractor comprises an inflatable balloon configured to retract specific organs and tissues at the site of the endoscopic procedure , with attached inflation and deflation means . in one embodiment , the inflatable retractor is attached to an outer tube or cannula . a second , inner cannula is placed within the outer cannula and attached thereto by a plurality of substantially elastic strands . the strands center the inner cannula while allowing it to be manipulated in any direction .