Surgical stapler with expandable jaw

A surgical stapler comprising:

• an elongate shaft having a proximal end and a distal end and defining a longitudinal axis between the proximal end and the distal end;
• a handle assembly disposed at the proximal end of the elongate shaft;
• an actuation mechanism actuatable by the handle assembly, the actuation mechanism comprising an actuation beam extending through at least a portion of the elongate shaft;
• a jaw assembly disposed at the distal end of the elongate shaft, the jaw assembly comprising:
• a first jaw defining a first clamping surface;
• a second jaw defining a second clamping surface;
• and
• a plurality of staples positioned in the first jaw;
• wherein the jaw assembly is actuatable by longitudinal movement of the actuation beam between a closed position in which the first clamping surface contacts the second clamping surface, an open position in which the second clamping surface extends at an angle transverse to the first clamping surface, and a stapling position in which the first clamping surface extends parallel to the second clamping surface and is spaced apart from the second clamping surface.