turning to the drawings , wherein like numerals denote like components throughout the several views , in fig1 , a surgical stapling and severing instrument 10 includes a handle portion 12 that is manipulated to position an implement portion 14 including a fastening end effector , depicted as a staple applying assembly 16 , distally attached to an elongate shaft 18 . the implement portion 14 is sized for insertion through a cannula of a trocar ( not shown ) for an endoscopic or laparoscopic surgical procedure with an upper jaw ( anvil ) 20 and a lower jaw 22 of the staple applying assembly 16 closed by depression of a closure trigger 24 toward a pistol grip 26 of the handle portion 12 , which advances an outer closure sleeve 28 of the elongate shaft 18 to pivot shut the anvil 20 . once inserted into an insufflated body cavity or lumen , the surgeon may rotate the implement portion 14 about its longitudinal axis by twisting a shaft rotation knob 30 that engages across a distal end of the handle 12 and a proximal end of the elongate shaft 18 . thus positioned , the closure trigger 24 may be released , opening the anvil 20 so that tissue may be grasped and positioned . once satisfied with the tissue held in the staple applying assembly 16 , the surgeon depresses the closure trigger 24 until locked against the pistol grip 26 , clamping tissue inside of the staple applying assembly 16 . then a firing trigger 32 is depressed , drawn toward the closure trigger 24 and pistol grip 26 , thereby distally advancing a firing member , depicted as including a proximal firing rod 34 attached to a distal firing bar 36 , that is supported within a frame ground 38 that connects the handle portion 12 to the staple applying assembly 16 . the firing bar 36 engages an elongate staple channel 40 and actuates a staple cartridge 42 contained therein , both forming the lower jaw 22 . the firing bar 36 also engages the closed anvil 20 . after releasing the firing trigger 32 to retract the firing bar 36 , depression of a closure release button 44 unclamps the closure trigger 24 so that the closure sleeve 28 may be retracted to pivot and open the anvil 20 to release the severed and stapled tissue from the staple applying assembly 16 . in fig2 , the staple applying assembly 16 is closed upon compressed tissue 46 . in fig2 – 3 , the firing bar 36 has a proximal portion 48 that is attached to a distal e - beam 50 that translates within the staple applying assembly 16 . as depicted with the firing bar 36 retracted , a vertical portion 52 of the e - beam 50 resides essentially aft of the staple cartridge 42 , as after a new staple cartridge 42 has been inserted into the elongate staple channel 40 . an upper pin 54 that extends laterally from an upper portion of the vertical portion 52 of the e - beam 50 initially resides within an anvil pocket 56 recessed near a proximal pivoting end of the anvil 20 . as the e - beam 50 is distally advanced during firing , the vertical portion 52 passes through a narrow longitudinal anvil slot 58 ( fig1 , 11 ) formed in an undersurface 60 of the anvil 20 , a proximally open vertical slot 62 formed in the staple cartridge 42 and an underlying longitudinal channel slot 64 formed in the elongate staple channel 40 . in fig2 , 11 , the narrow longitudinal anvil slot 58 ( fig2 ) communicates upwardly to a laterally widened longitudinal anvil channel 66 sized to slidingly receive the upper pin 54 . the longitudinal channel slot 64 communicates downwardly to a laterally widened longitudinal channel track 68 that receives a lower foot 70 , which is sized to slide therein and is attached at a bottom of the vertical portion 52 of the e - beam 50 . a laterally widened middle pin 72 extending from the vertical portion 52 of the e - beam 50 is positioned to slide along a top surface of a bottom tray 74 of the staple cartridge 42 , which in turn rests upon the elongate staple channel 40 . a longitudinal firing recess 75 formed in the staple cartridge 42 above the bottom tray 74 is sized to allow the middle pin 72 to translate through the staple cartridge 42 . a distal driving surface 76 of the vertical portion 52 of the e - beam 50 is positioned to translate through the proximally open vertical slot 62 of the staple cartridge 42 and distally drive a wedge sled 78 proximally positioned in the staple cartridge 42 . the vertical portion 52 of the e - beam 50 includes a cutting surface 80 along a distal edge above the distal driving surface 76 and below the upper pin 54 that severs the clamped tissue 46 simultaneously with this stapling . with particular reference to fig1 , it should be appreciated that the wedge sled 78 drives upwardly staple drivers 82 that in turn drive upwardly staples 83 out of staple apertures 84 formed in a staple body 85 of the staple cartridge 42 to form against the undersurface 60 of the anvil 20 ( fig2 ). in fig2 , 11 , advantageously , the illustrative spacing , denoted by arrow 86 ( fig2 ), between the upper pin 54 is compliantly biased toward a compressed state wherein 0 . 015 inches of compressed tissue 46 is contained in the staple applying assembly 16 . however , a larger amount of compressed tissue 46 up to about 0 . 025 inches is allowed by an inherent flexure of the e - beam 50 . excessive flexure , of perhaps up to 0 . 030 inches , is avoided should the length of staples be insufficient to form with the additional height . it should be appreciated that these dimensions are illustrative for a staple height of 0 . 036 inches . the same would be true for each category of staple , however . in fig4 . a first version of a compliant e - beam 50 a includes top and bottom horizontal slits 90 , 92 from a distal edge of the vertical portion 52 a , perhaps formed by electro drilling machine ( edm ). the vertical portion 52 a thus contains a vertically compliant top distally projecting arm 94 containing the upper pin 54 , a knife flange 96 containing the cutting surface 80 , and a lower vertical portion 98 containing the distal driving surface 76 , middle pin 72 and lower foot 70 . the horizontal slits 90 , 92 allow a compliant vertical spacing by allowing the top distally arm 94 to pivot upwardly to adjust to increased force from compressed tissue 46 ( not shown ). in fig5 – 6 , a second version of a compliant e - beam 50 b includes left and right lower relieved areas 110 , 112 formed into an upper pin 54 b to each side of the vertical portion 52 , leaving left and right lower bearing points 114 , 116 respectively . the outboard position of the bearing points 114 , 116 provides a long moment arm to exert the force to flex . it should be appreciated given the benefit of the present disclosure that the dimensions of the relieved areas 110 , 112 and the choice of materials for the compliant e - beam 50 b may be selected for a desired degree of flexure , given the staple size and other considerations . in fig7 , a third version of a compliant e - beam 50 c is as described above in fig5 – 6 with further flexure provided by left and right upper narrow relieved areas 120 , 122 formed into opposite top root surfaces of an upper pin 54 c proximate to the vertical portion 52 . in fig8 , a fourth version of a compliant e - beam 50 d is as described for fig2 – 3 with an added feature of a composite / laminate vertical portion 52 d that includes a central resilient vertical layer 130 sandwiched between left and right vertical layers 132 , 134 that support respectively left and right portions 136 , 138 of an upper pin 54 d . as the left and right portions 136 , 138 are flexed either up or down , the resulting bowing of the left and right vertical layers 132 , 134 are accommodated by a corresponding compression or expansion of the central resilient vertical layer 130 . in fig9 , a fifth version of a compliant e - beam 50 e is as described for fig2 – 3 with an added feature of a discrete upper pin 54 e formed of a more flexible material that is inserted through a horizontal aperture 140 through a vertical portion 52 e . thus , left and right outer ends 142 , 144 of the discrete upper pin 54 e flex in accordance with loading forces . alternatively or in addition to incorporating flexure into an upper pin 54 , in fig1 – 11 , a sixth version of a compliant e - beam 50 f as described for fig2 – 3 further includes resilient pads 150 that are attached to upper surfaces 152 of the bottom foot 70 . the resilient pads 150 adjust the spacing of the upper pin 54 in accordance to the compression force experienced at the bottom foot 70 . in fig1 , a seventh version of a compliant e - beam 50 g is as described above for fig2 – 3 with the added feature of a bottom foot ( shoe ) 70 g having an upwardly aft extended spring finger 160 that resiliently urges the e - beam 50 g downwardly to adjust vertical spacing in accordance with loading force . in fig1 , an eighth version of a compliant e - beam 50 h is as described above in fig2 – 3 with the added feature of an oval spring washer 170 resting upon the bottom foot 70 encircling the vertical portion 52 and having an upwardly bowed central portion 172 that resiliently urges the e - beam 50 h downwardly to adjust vertical spacing in accordance with loading force . while the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail , it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail . additional advantages and modifications may readily appear to those skilled in the art . for example , while a manually operated surgical stapling and severing instrument 10 is depicted for clarity , it should be appreciated that robotically manipulated and / or controlled fastening devices may incorporate a force controlled firing bar . for another example , a compliant e - beam consistent with aspects of the present invention may include engagement to an anvil similar to the engagement in the illustrative versions of two structures that slide against opposite sides of the elongate staple channel . similarly , a compliant e - beam may engage a lower jaw by having a laterally widened portion that slides internally within a channel formed in a lower jaw structure . as yet an additional example , in the illustrative version , the staple cartridge 42 is replaceable so that the other portions of the staple applying assembly 16 may be reused . it should be appreciated given the benefit of the present disclosure that applications consistent with the present invention may include a larger disposable portion , such as a distal portion of an elongate shaft and the upper and lower jaws with a staple cartridge permanently engaged as part of the lower jaw . as yet another example , the illustrative e - beam advantageously affirmatively spaces the upper and lower jaws from each other . thus , the e - beam has inwardly engaging surfaces that pull the jaws together during firing in instances where a larger amount of compressed tissue tends to spread the jaws . thereby the e - beam prevents malformation of staples due to exceeding their effective length . in addition , the e - beam has outwardly engaging surfaces that push the jaws apart during firing in stances where a small amount of tissue or other structure attributes of the instrument tend to pinch the jaws together that may result in staple malformation . either or both functions may be enhanced by applications consistent with aspects of the invention wherein inherent flexure in the e - beam adjusts to force to allow a degree of closing of the jaws or of opening of the jaws .
a surgical instrument for being endoscopically or laparoscopically inserted into a surgical site for simultaneous stapling and severing of tissue includes force adjusted spacing between an upper jaw and a lower jaw so that the height of staple formation corresponds to the thickness of the tissue , yet does not exceed the height range that may be accommodated by the length of the staples . in particular , resilient structures are formed into an e - beam firing bar that includes a cutting surface that severs tissue between a top pin that engages the anvil and a middle pin and lower foot that engage the lower jaw . the resilience responds to the force exerted by clamped tissue to vary the spacing .