this disclosure relates to a surgical instrument assembly and system for use with delicate tissues and methods of using the instrument assembly . the instruments are designed for use during surgery on delicate tissues , such as brain and breast tissues , although they may be used in any medical context . the instrument assembly includes several portions , such as , an introducer portion , a tissue access channel retractor portion (“ channel portion ”) having at least one handle portion , and a stylette portion . these instrument portions are formed to maximize the surface area of the retractor , which distributes pressure approximately equally though out the surrounding tissues and minimizes effective localized retraction pressure on the tissues in contact or immediately surrounding the instrument . in one embodiment , the surgical instrument assembly can be a retractor in the form of an arch or arc shape , into which an arch or arc shaped wedge introducer may be inserted for surgical access to the external portions or surfaces of the brain . in another embodiment , the surgical instrument assembly can be a retractor in the form of a wedge with a tapered elliptical cross sectional shape , into which a tapered elliptical cross sectional introducer may be inserted for surgical access to the external portions or surfaces of the brain . alternatively , the external retractor and wedge introducer may be used to insert medical / cosmetic devices into or under delicate tissues . the surgical instrument assembly system may also employ the external retractor as an external brain support buttress channel portion to lift the brain mass upward with respect to the cranium to provide stability and prevent the gelatinous brain materials from shifting during surgery . in the capacity of a brain support buttress channel portion (“ buttress portion ”) also provides improved visualization and improved access to the surgical area by lifting the brain matter upward in the cranium . the formation of the instrument assembly also eliminates the need to “ pull ” a retractor against tissue portion to clearly visualize the surgical area by initially providing a sufficient work area via the channel retractor . the use of the tissue access channel retractor portion of the instrument assembly eliminates or greatly lowers the possibility of accidental over - retraction . by avoiding excess retraction , dainage to the surrounding tissues is also avoided , including possible brain damage . while other closed curve configurations may be used , the preferably elliptical or arch shaped architecture formation of the instrument assembly portions is such that medical staff is afforded binocular vision , rather than the monocular vision typically found in similar devices . this elliptical architecture also provides far greater clearance for lighting access to illuminate the target surgical area and allows full visualization of that area . the forward edge of the channel retractor is preferably tapered to gently separate tissue to obtain a surgical area and minimizes disruption of the tissue . the surgical instrument assembly system may also be useful as an inserter instrument for breast implants . the dimensions of the surgical instrument assembly may vary and be modified according to an intended use . generally , the surgical work space formed by the introducer portion 40 can have diameters of in the range of approximately 10 millimeters (“ mm ”) to approximately 100 mm , and more typically in the range of approximately 25 mm to approximately 75 mm in its closed configuration . the open configuration of the introducer portion 40 may extend the diameter of the distal end 42 of the introducer portion 40 several millimeters , and may generally be determined by amount of extension desired by the surgical team during use as it is introduced into the lumen 22 of the retractor 20 , and may include a flexible band portion 14 to enhance its flexibility . the open configuration may also be determined by the overall desired circumference and diameter of the surgical instrument assembly for a particular use and may be manufactured in a variety of useful sizes to be available as is practical . the surgical instrument assembly may be formed of any biocompatible material which will provide sufficient stability and strength necessary to provide a surgical work area . the biocompatible material may be disposable or sterilize - able for repeated use . in one embodiment , the surgical instrument assembly may be formed of a lightweight plastic material for ease of manipulation and / or the material may be transparent to allow direct visualization of underlying brain tissue thorough the instrument assembly portions . the surgical instrument assembly system also enables integration with stereotactic neuro - navigation computer guidance systems to enhance visualization of the surgical area of the brain . fig1 illustrates in diagrammatic fashion the surgical instrument assembly system 10 adjacent a surgical aperture in the cranium of an intubated patient . an external retractor system 100 is also spaced from the lower skull , and will be described later in the specification . fig2 is an enlarged perspective view of the surgical instrument assembly system 10 as shown in fig1 . the instrument assembly system 10 is comprised of two components , a retractor 20 , and an introducer 40 . fig3 illustrates the relationship of introducer 40 to retractor 20 , prior to assembly . it is desirable that the introducer is easily fixed to and removable from the retractor both prior to and during the surgical procedure . as also shown in fig3 , the surgical instrument assembly system may be formed by any method , including injection molding , as a single piece , or may be formed of two or more pieces which are permanently fixedly attached to each other . the distal end 42 of the introducer portion 40 is preferably a solid , rounded cone shape which may or may not include an opening 52 to the surrounding tissues as opposed to a cannula structure which always provides a distal opening . the distal end 42 preferably includes a gently increasing circumference 54 , which increases and expands towards the proximal end 56 of the introducer portion 42 . the introducer portion 40 has a main body 50 , and may be divided into two approximate handle halves 46 , having v - shaped cutouts 48 between the handle halves . the halves of the proximal end 56 are an integral unit , the term “ halves ” is used as a descriptor only and does not describe separable parts , as opposed to two disassemblable halves . the proximal end 56 may include at least one handle portion 46 which extends outwardly at an angle of approximately 90 degrees . a handle portion 46 may be useful to allow a medical team member to physically insert , manipulate or hold the handle portion 46 , or a conventional surgical fixation cable may be attached to the handle portion 12 . at least one of the handle portions 46 include at least one indentation or groove 44 to accept or snap into an additional portion of the surgical instrument assembly 10 . fig4 - 8 show a variety of views of the retractor portion 20 of this disclosure , including retractor 20 having a hollow working channel 22 and handle 28 . the retractor 20 is generally formed to dimensions and shapes to coincide with the introducer portion 40 that may be slideably inserted into the brain access work channel 22 of the retractor portion 20 . the retractor portion 20 is generally shorter in length than the introducer portion 40 to allow the distal end 42 of the introducer portion 40 to interact with the surrounding housing 21 tissues . as best seen in fig6 and 7 , the retractor portion 20 is formed as a hollow elliptical rounded wedge having a tapered distal leading edge 24 . the proximal edge of the retractor 20 includes a slightly rounded lip 26 and a handle portion 28 . at least one tab 30 is formed in wedge 21 , just distal of lip 26 . tab 30 will positively align with groove 44 of introducer 40 to prevent or inhibit unnecessary movement or slipping of the instrument assembly components best seen in sectional view fig1 . the handle portion 28 allows the retractor portion 20 to be fixed in space with the use of a standard or conventional neurosurgical fixation cable device . fig9 illustrates a side view of a retractor 20 , having a proximal end 26 of the surgical instrument assembly and optionally having a handle portion 28 perpendicular to the proximal end 26 ; and an elliptical length of the retractor 21 extends to the rounded distal end 24 . fig1 is a frontal view of the retractor 20 , showing the lumen 30 and the handle portion 28 . fig1 is a cross - sectional view of the retractor 20 of the rounded shape of the retractor 20 to avoid damage to delicate tissues . fig1 is a top plan view of the retractor 20 , emphasizing the groove like cut - out hole 30 which can allow the introducer 40 to integrally fit and temporarily lock / snap into hole 30 , thereby causing both the retractor 20 and introducer 50 to function as one , while desired by the medical team . fig1 is an enlarged view of the grooved hole 30 . fig1 is a cross - sectional view of the tab 44 of the introducer 20 while it is engaged within the grooved hole 30 of the retractor 20 . shown in fig1 is a proximal end view of assembled instrument where the handle portions 46 overlying lip 26 of retractor 20 , and v - shaped cutouts 48 residing in lumen 22 . handle 28 of retractor 20 is molded integral with lip 26 , providing both rigidity and strength . fig1 also shows that where a base of handle 28 is attached to retractor 20 , handle 28 may optionally merge in a cascading shaped dip 28 a , interrupting the continuous curve of the proximal end of hollow retractor 20 . such a cascading dip 28 a allows for easier finger access into the working channel of hollow retractor 20 . fig1 - 20 illustrate diagrammatically the method if installing surgical instrument assembly 10 into the aperture 12 in cranium 14 . as seen in fig1 , instrument assembly 10 is inserted into aperture 12 . distal end 42 of introducer 40 is abutting brain tissue 60 . as instrument assembly 10 is introduced , distal end 42 of introducer 40 begins to spread tissue or lobes 62 and 64 of brain 60 , as shown in fig1 . fig1 is an elevational view of the installed surgical instrument assembly 10 , taken along arrows 18 - 18 of fig1 . upon installation , handles 46 of introducer 40 may be flexed inward , thereby releasing the tab 30 of retractor 20 from the groove 44 of introducer 40 . fig1 illustrates introducer 40 during removal from lumen 22 of retractor 20 . fig2 shows surgical instruments 70 within lumen 22 of retractor 20 , examining brain tissue 60 . fig2 is a diagrammatic perspective view of an embodiment of the surgical instrument assembly 10 , adjacent an aperture 12 located at the temple region of a patient &# 39 ; s cranium 14 . in this embodiment , the overall length of surgical instrument assembly 10 is sufficient to transversely penetrate the cranium and brain tissue 60 . surgical instrument assembly 10 is shown installed in fig2 . fig2 is a perspective view of the external retracting buttress channel 100 . external buttress channel instrument assembly 100 is comprised of buttress channel component 200 , and wedge introducer component 400 . external buttress channel component 200 has a generally arched , hemi - elliptical architecture , where it is wider along the base than it is tall or high . the buttress channel component 200 includes a smooth , tapered leading edge 202 . a handle fixation member 204 is approximately perpendicular to the rounded lip 206 of the proximal end 208 . the handle member 204 may be employed as an attachment point to a standard neurosurgical armature fixation device . the external buttress channel component 200 may be used to lift , support or manipulate the brain within the skull cavity to provide additional or improved vision of the surgical area , as seen in fig2 . also seen in fig2 is the external wedge introducer portion 400 for the external buttress channel component 200 . buttress channel 200 is designed to gain access to external structures along , around or beneath the brain by elevating the surfaces of the brain to allow access to surgical locations on or near the surface of the brain tissues . in operation , prior to insertion , introducer portion 400 is attached to buttress channel 200 such that sloping distal end 402 protrudes from the distal open end 210 of buttress channel 200 . this pushes away brain tissue at the outer brain surface 66 gently during insertion . after insertion , introducer portion 400 is withdrawn to leave a working channel of decreasing hemi - oval cross section from proximal end 208 to distal end 210 . radial surface of buttress channel 200 supports the outer surface 66 of the brain tissue 60 , best seen in fig2 . note that surface of wedge introducer 400 conforms to the inside of buttress channel surface ; proximal end 208 and handle member 204 conform to proximal end 406 and fixation member 408 of introducer 400 respectively . fixation member 204 of buttress channel 200 is designed to be attached to a standard neurosurgical armature fixation device . fig2 and 26 are diagrammatic view of the instruments working on an external tumor , where the further surgical instruments 70 are inserting into the operating space formed by the instrument assembly system to allow the surgical team to work on the tissues as necessary . fig2 is a diagrammatic view of an embodiment , which may be installed through the forehead as necessary for surgical procedures . fig2 is a diagrammatic view of the instrument assembly installed into breast tissue 68 , where it may be used for insertion of implants 72 and the like . fig2 shows use of an arched buttress channel 200 and wedge introducer component 400 which may be used , for example , for access to brain tissue or for inserting an inflatable prosthesis into breast tissue . fig2 is a perspective exploded view of a surgical kit . the kit 600 includes an injection - molded or vacuum - formed housing 602 , providing cavities 604 to receive components of the surgical instrument assembly system 10 and the external retracting buttress channel system 100 . a stylette 80 may also be included . upon placement of all desired components within the housing 602 , the sterile kit will be sealed with a tyvek sheet 606 . upon removal of sheet 606 by the surgeon , the sterile components of kit 600 can be utilized and employed as required in a surgical operation . in the foregoing description , certain terms and visual depictions are used to illustrate the preferred embodiment . however , no unnecessary limitations are to be construed by the terms used or illustrations depicted , beyond what is shown in the prior art , since the terms and illustrations are exemplary only , and are not meant to limit the scope of the present invention . it is further known that other modifications may be made to the present invention , without departing the scope of the invention , as noted in the appended claims .
surgical methods providing access to delicate tissue , such as brain tissue or breast tissue , through a transcutaneous incision . a method may include making an incision adjacent a region containing delicate tissue , and providing a surgical assembly having : a retractor having a hollow sleeve extending from a proximal end to a distal end , and an introducer having a proximal end installed within the hollow sleeve and a distal end extending beyond the distal retractor end . the surgical assembly is advanced into the region containing delicate tissue , and the distal introducer end gently displaces the delicate tissue as the surgical assembly is advanced to thereby avoid damage to the delicate tissue . the introducer is removed from the retractor to leave the distal retractor end at a surgical site located in the physical region containing delicate tissue . one or more surgical instruments are then used through the hollow sleeve .