A surgical stapler (10) comprising: a shaft portion having a proximal end and a distal end； first and second cartridge channels (140a, 140b) extending through the shaft portion, each of the first and second cartridge channels having a distal end defining a U-shaped member (208)； a pivot member (157) pivotably coupled to the distal end of the shaft portion, the pivot member being fixedly coupled to the first cartridge channel (140a) by a first post (172) and fixedly coupled to the second cartridge channel (140b) by a second post (172)； and a tool assembly (114) including an anvil (182) and a cartridge assembly (180), the cartridge assembly including a cartridge body (184) and a plurality of staples (186), the cartridge body having a first leg (188) supported in the U-shaped member of the first cartridge channel and a second leg (188) supported in the U-shaped member of the second cartridge channel； wherein the first and second cartridge channels are movable axially in opposite directions to pivot the pivot member (157) in relation to the shaft portion and effect articulation of the tool assembly.
