1.  Field of the Invention
The present invention generally concerns surgical cutting and fastening instruments and, more particularly, motor-driven surgical cutting and fastening instruments. 
2.  Description of the Related Art
Endoscopic surgical instruments are often preferred over traditional open surgical devices since a smaller incision, or incisions, associated with endoscopic surgical techniques tends to reduce the post-operative recovery time and complications.  Consequently, significant development has gone into a range of endoscopic surgical instruments that are suitable for precise placement of a distal end effector at a desired surgical site through a cannula of a trocar.  These distal end effectors engage the tissue in a number of ways to achieve a diagnostic or therapeutic effect (e.g., endocutter, grasper, cutter, staplers, clip applier, access device, drug/gene therapy delivery device, and energy device using ultrasound, RF, laser, etc.). 
Known surgical staplers include an end effector that simultaneously makes a longitudinal incision in tissue and applies lines of staples on opposing sides of the incision.  The end effector includes a pair of cooperating jaw members that, if the instrument is intended for endoscopic or laparoscopic applications, are capable of passing through a cannula passageway.  One of the jaw members receives a staple cartridge having at least two laterally spaced rows of staples.  The other jaw member defines an anvil having staple-forming pockets aligned with the rows of staples in the cartridge.  The instrument includes a plurality of movable wedges which, when driven distally, pass through openings in the staple cartridge and engage drivers supporting the staples to effect the firing of the staples toward the anvil. 
An example of a surgical stapler suitable for endoscopic applications is described in U.S. Pat.  No.  5,465,895, the disclosure of which is hereby incorporated by reference in its entirety, which discloses an endocutter with distinct closing and firing actions.  A clinician using this device is able to close the jaw members upon tissue to position the tissue prior to firing.  Once the clinician has determined that the jaw members are properly gripping tissue, the clinician can then fire the surgical stapler with a single firing stroke, or multiple firing strokes, depending on the device.  Firing the surgical stapler causes severing and stapling of the tissue.  The simultaneous severing and stapling avoids complications that may arise when performing such actions sequentially with different surgical tools that respectively only sever or staple.