preferred embodiments of the presently disclosed expansion assembly insertion apparatus will now be described in detail with reference to the drawing figures wherein like reference numerals identify similar or identical elements . in the drawings and in the description which follows , the term “ proximal ”, as is traditional will refer to the end of the surgical device or instrument of the present disclosure which is closest to the operator , while the term “ distal ” will refer to the end of the device or instrument which is furthest from the operator . referring now in detail to the drawing figures , as seen in fig1 , a radially expandable dilation assembly is generally designated with the reference numeral 10 . radially expandable dilation assembly 10 includes a tubular sheath 12 having a proximal end 14 , a distal end 16 and an axial lumen 15 extending therethrough . axial lumen 15 defines a longitudinal axis “ x ” and further defines a first cross - sectional area extending therethrough . proximal end 14 is tapered radially outward in the proximal direction and is secured to a handle 18 . handle 18 includes an aperture 20 extending therethrough and interconnected with lumen 15 of tubular sheath 12 . tubular sheath 12 may be made from any material which is capable of receiving an expansion assembly to effect radial expansion of sheath 12 , as described in more detail hereinafter . sheath 12 preferably includes an inelastic braid covered by an elastic membrane , as described in commonly assigned u . s . pat . no . 5 , 431 , 676 , the full disclosure of which is incorporated herein by reference . suitable expandable sleeves 10 may be obtained commercially from united states surgical , a division of tyco healthcare , ltd ., as part of the step ™ introducer system . a pneumoperitoneum needle assembly 30 including a tubular needle 32 and a stylet 34 is illustrated in fig2 . tubular needle 32 includes a hub 36 having a male bayonet connector 38 at a proximal end thereof . preferably , stylet 34 is spring loaded in a proximal connector 40 which includes a male bayonet fitting 42 . male bayonet fitting 42 is receivably coupled to female bayonet fitting ( not illustrated ) of hub 36 . an insufflation valve 44 is connected to the proximal end of stylet 34 and a port 46 is formed in a distal end thereof . port 46 permits the introduction of insufflation gas through valve 44 to be released through stylet 34 . in use , stylet 34 is mounted within needle 32 with bayonet fitting 42 attached to hub 36 . the distal end of stylet 34 in turn extends from a distal end 48 of needle 32 such that stylet 34 will retract into needle 32 when needle assembly 30 is engaged against tissue , as described in more detail below . referring now to fig3 , an expansion assembly 50 is shown and described . expansion assembly 50 includes an expansion member 52 ( i . e ., a cannula tube ) and a proximal hub 54 . expansion member 52 includes a threaded connector 56 at its proximal end which can be removably secured to a fitting 58 in the distal end of proximal hub 54 . preferably , expansion member 52 defines a second cross - sectional area which is larger than the first cross - sectional area of tubular sheath 12 . with reference to fig4 , an obturator 70 including a shaft 72 having a tapered distal end 74 and a handle 76 is shown and described . as will be described in greater detail below , obturator 70 is intended to be placed within a central lumen of cannula assembly 50 in order to facilitate insertion of expansion assembly 50 into radially expandable dilation assembly 10 . turning now to fig5 , an expansion assembly insertion apparatus in accordance with the present disclosure , having an expansion assembly 50 and a dilation assembly 10 operatively mounted thereto , is shown generally as reference numeral 100 . insertion apparatus 100 includes a proximally extending fixed handle 102 , a trigger 104 pivotably coupled to fixed handle 104 at pivot pin 118 , and a distally extending spine member 106 . spine member 106 has a distal end 108 and a proximal end 110 defining a longitudinal axis “ x ′”. proximal end 110 of spine member 106 is slidably received within fixed handle 102 through an aperture 102 a formed in a distal end of fixed handle 102 . while a generally rectangular cross - section for spine member 106 has been depicted it is contemplated that spine member 106 can have a circular , elliptical , square or other polygonal cross - section . distal end 108 of spine member 106 is provided with a yoke or engaging feature 112 operatively coupled thereto . yoke 112 defines a u - shaped clevis 114 having a pair of legs 116 , 117 . preferably , clevis 114 includes a distal pair of legs 116 a , 117 a and a proximal pair of legs 116 b , 117 b . legs 116 , 117 define an axis which is substantially parallel to the longitudinal “ x ′” axis of spine member 106 . in use , u - shaped clevis 114 of yoke 112 receives handle 18 of dilation assembly 10 therein . in particular , handle 18 includes a pair of diametrically opposed tabs 18 a , 18 b wherein either tab 18 a or 18 b is positioned between distal and proximal legs 116 a and 116 b while the other of tab 18 a or 18 b is positioned between distal and proximal legs 117 a and 117 b . as best seen in fig6 , fixed handle 102 includes an actuation mechanism for the mechanical operation of insertion apparatus 100 . the actuation mechanism includes a linkage member 120 having a first end 120 a which is pivotably coupled to trigger 104 at a pivot point 122 and a second end 120 b which is slidably received within fixed handle 102 and pivotably coupled to a driving lever 130 . driving lever 130 is located and / or suspended on spine member 106 which passes through an aperture or opening 132 formed in driving lever 130 . a compression spring 134 disposed between driving lever 130 and an inner surface of fixed handle 102 urges driving lever 130 in a distal direction and to remain orthogonal relative to spine member 106 . the force of spring 134 urges trigger 104 against a backing member 126 , via linkage member 120 , of fixed handle 102 thus providing a standby condition . in the standby condition , driving lever 130 is positioned substantially perpendicular to the direction of motion , indicated by the arrow “ p ”, of spine member 106 when in operation . motion of trigger 104 about the pivot pin 118 causes spine member 106 to move against the bias of spring 134 , as will be described in greater detail below . the actuation mechanism further includes a braking lever 136 having an opening 138 through which spine member 106 passes . one end 140 of braking lever 136 is pivotably positioned in a recess 142 formed in fixed handle 102 such that braking lever 136 may pivot within constraints defined by the surfaces of recess 142 and by the binding of braking lever 136 with spine member 106 when the edges of opening 138 in braking lever 136 engage the surfaces of spine member 106 . at least one compression spring 144 is disposed between a wall 146 in fixed handle 102 and braking lever 136 . spring 144 effectively biases the free end of braking lever 136 distally away from driving lever 130 . the biased position of braking lever 136 is limited by the binding and / or cocking interference between opening 138 of braking lever 136 and the surfaces of spine member 106 . in the embodiment illustrated in fig6 , braking lever 136 extends in the direction of fixed handle 102 so that its distal end 148 can be suitably gripped by the thumb of a user . it should be noted that in the standby position illustrated in fig6 , driving lever 130 is substantially perpendicular to the longitudinal “ x ′” axis of spine member 106 , whereas the portion of braking lever 136 which engages spine member 106 is transversely oriented to the longitudinal “ x ′” of spine member 106 at a slight angle . in this condition , if a force is applied to yoke 112 ( fig5 ) in the direction indicated by arrow “ p ”, slide member 106 is free to move through fixed handle 102 . since braking lever 136 is free to pivot against the bias of spring 144 when force is applied on yoke 112 , in the direction of arrow “ p ”, braking lever 136 presents no obstacle to the motion of spine member 106 and yoke 112 and thus may be advanced continuously through fixed handle 102 . however , in the standby position , as illustrated in fig6 , if a force is applied to yoke 112 in the direction opposite to the direction indicated by arrow “ p ”, the edges of opening 138 in braking lever 136 bind against the surfaces of spine member 106 and it is not possible to withdraw the moving yoke 112 further away from fixed handle 102 . compression of spring 144 , by pressing on braking lever 136 with a finger in the direction of the arrow “ p ”, allows withdrawal of spine member 106 and yoke 112 to be extended away from fixed handle 102 . compression of spring 144 brings distal end 148 of braking lever 136 into perpendicularity with the direction of intended motion of spine member 106 , and thus spine member 106 is then free to slide in either direction through opening 136 in braking lever 136 . the preferred method of use of expansion assembly insertion apparatus 100 is to squeeze trigger 104 ( toward fixed handle 102 ) to incrementally advance spine member 106 and yoke 112 through fixed handle 102 . when trigger 104 is squeezed , pivoting occurs about pivot pin 118 and second end 120 b of linkage member 120 also moves substantially in the direction of arrow “ p ”. this causes driving lever 130 to pivot about its first end 131 so that driving lever 130 is no longer perpendicular to the direction “ p ” of intended motion of spine member 106 . pivoting of driving lever 130 compresses spring 134 and also causes the end edges of aperture 132 , formed in driving lever 130 to bind against the surfaces of spine member 106 . binding occurs because driving lever 130 is no longer perpendicular to the direction “ p ” of intended motion of spine member 106 . further motion of trigger 104 causes driving lever 130 to translate in the direction of arrow “ p ”. this motion further compresses spring 134 and in the process , by means of the binding and / or cocking interference between driving lever 130 and spine member 106 , advances spine member 106 and its connected yoke 112 through fixed handle 102 . the maximum distance of advancement of yoke 112 , with one squeeze of trigger 104 , is limited to when spring 134 is fully compressed or trigger 104 strikes the surface of fixed handle 102 . after trigger 104 is fully pivoted about pivot pin 118 , release of trigger 104 causes the return of trigger 104 to the stand by condition due to spring 134 urging driving lever 130 to a perpendicular position and pressing linkage member 120 into trigger 104 . returning to fig5 , fixed handle 102 is further provided with at least one , preferably a pair of resilient c - shaped cuffs 124 affixed to a distal end thereof . cuffs 124 define a longitudinal axis which is substantially aligned with the axis of clevis 114 defined by legs 116 , 117 . in use , cuffs 124 are configured to receive proximal hub 54 of cannula assembly 50 therein by a snap - fit type engagement . in addition , fixed handle 102 is provided with a backing member 126 as described above . backing member 126 preferably extends transversely from fixed handle 102 beyond the longitudinal axis of cuffs 124 . accordingly , in operation , backing member 126 preferably acts as a stop for a proximal end surface of expansion assembly 50 when expansion assembly 50 is mounted to expansion assembly insertion apparatus 100 . while insertion apparatus 100 has been shown and described herein as including a trigger 104 for incrementally approximating clevis 114 toward cuffs 124 , it is envisioned and within the scope of the present disclosure that any operation member may be used to accomplish that same function . for example , the operation member may include a ratchet mechanism , a screw drive , a pneumatic drive or the like to advance clevis 114 toward cuffs 124 . referring now to fig7 - 10 , a preferred method of operation of expansion assembly insertion apparatus 100 , will be described . initially , as seen in fig . radially expandable dilation assembly 10 , having pneumoperitoneum needle assembly 30 inserted therein , is introduced through a patient &# 39 ; s abdomen “ a ” ( or other body location ) by engaging sharpened distal end 48 of needle assembly 30 against the tissue of the patient &# 39 ; s abdomen “ a ” and advancing the sleeve / needle combination forward until tubular sheath 12 of dilation assembly 10 extends across the tissue of abdomen “ a ”. needle assembly 30 is then removed , and an expansion assembly 50 including an obturator 70 disposed therewithin is introduced through tubular sheath 12 of dilation assembly 10 , with the aid of expansion assembly insertion apparatus 100 thereby resulting in radial expansion of tubular sheath 12 ( see fig9 ). in particular , yoke 112 of insertion apparatus 100 is preferably first hooked onto handle 18 of dilation assembly 10 as described above . next , expansion assembly 50 , including obturator 70 , is loaded into insertion apparatus 100 by coupling proximal hub 54 of expansion assembly 50 to cuffs 124 as described above . finally , insertion apparatus 100 is actuated by repeatedly squeezing trigger 104 , as described above , in order to incrementally advance expansion assembly 50 and obturator 70 through dilation assembly 10 . as expansion assembly 50 and obturator 70 are moved distally through tubular sheath 12 , dilation assembly 10 is radially expanded from the first cross - sectional area to the second cross - sectional area . finally , as illustrated in fig1 , obturator 70 is removed from expansion member 52 , leaving an access channel through abdominal wall “ a ” for the introduction of a variety of other surgical instruments through the access channel . an ergonomic feature of insertion apparatus 100 is the substantially longitudinally oriented fixed handle 102 and trigger 104 . in other words , fixed handle 102 is preferably aligned with the longitudinal axis of spine member 106 while trigger 104 is preferably pivotable to a closed position which is substantially aligned with the longitudinal axis of spine member 106 . thus , the longitudinal axis of insertion apparatus 100 is oriented in a substantially orthogonal direction with respect to the longitudinal axis of the forearm of the surgeon . accordingly , the application of the insertion force by the surgeon preferably occurs by the surgeon gripping fixed handle 102 and trigger 104 and pivoting his forearm about his elbow such that is hand travels in a direction substantially co - linear with the longitudinal axis of insertion apparatus 100 . turning now to fig1 , an exemplary package or “ kit ” containing various combinations of system components is illustrated . providing such kits is a particularly convenient way to facilitate inventory maintenance of the components necessary to reconstruct the access systems of the present disclosure . it will be appreciated , of course , that complete systems could be sold in kits , as well as each of the individual components can be sold in their own kits . in many cases , it will be desirable to combine the pairs of components or multiple pieces of a single component together in one package , particularly where the components are sized to match each other . the kits will include conventional package elements , typically pouches , envelopes , trays , boxes , foam inserts and other containers of a type commonly used for sterile or non - sterile packaging of surgical instruments . the packages will typically also include a “ package insert p ” which is a written instruction sheet with instructions on use , warnings , etc . as seen in fig1 , an exemplary kit 200 , for providing access to a target surgical site , includes a package 202 , typically non - sterile since the reusable components can be subsequently sterilized and at least one of the following items : a radially expandable dilation assembly 10 ; a pneumoperitoneum needle assembly 30 ; a stylet 34 ; an expansion assembly 50 ; and an obturator 70 . kit 200 further includes an expansion assembly insertion apparatus 100 . although the foregoing disclosure has been described in some detail by way of illustration and example , for purposes of clarity or understanding , it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims .
apparatus for forming and enlarging a percutaneous penetration are disclosed . the apparatus includes an elongate dilation member including a radially expandable member having a first cross - sectional area ; and an elongate expansion member including a tubular element having a second cross - sectional area which is larger than the first cross - sectional area . the apparatus further includes an advancing apparatus having a first arm with a first engaging feature for engaging the handle of the dilation member ; a second arm with a second engaging feature for engaging the handle of the expansion member ; and an operation member ; the first arm and the second arm being connected so that operation of the operation member approximates the first engaging feature and the second engaging feature together .