A closed member is provided for applying a closed motion to the movable jaw of the surgical instrument.In at least one embodiment, the closed member comprises a closed body defining an outer surface and an inner surface.The closed body further defines an upper portion having an upper wall thickness between the outer surface and the inner surface and a lower portion having a lower wall thickness between the outer surface and the inner surface.The upper wall thickness is different from the bottom wall thickness.The cam surface is formed on the upper portion to selectively cam contact with a portion of the movable jaw.外科用器具の可動顎部に閉鎖運動を適用するための閉鎖部材が提供される。少なくとも１つの形態では、閉鎖部材は、外側表面及び内側表面を画定する閉鎖本体を備える。閉鎖本体は、外側表面と内側表面との間の上壁厚さを有する上部分と、外側表面と内側表面との間の下壁厚さを有する下部分とを更に画定する。上壁厚さは、下壁厚さとは異なる。カム表面が、可動顎部の一部分と選択的にカム接触するように上部分に形成される。
