A surgical instrument, comprising: a handle; an elongate shaft extending from said handle, wherein said elongate shaft defines a shaft axis; an end effector comprising a plurality of detents; an articulation joint, wherein said end effector is rotatably coupled to said elongate shaft by said articulation joint about an articulation axis; an articulation knob rotatable between an unarticulated position and articulation positions; a first articulation member attached to a first side of said end effector and to said articulation knob; a second articulation member attached to a second side of said end effector and to said articulation knob; and an articulation lock comprising a lock member configured to move between a locked position where said lock member is engaged with a said detent of said end effector and an unlocked position where said lock member is disengaged from said end effector, wherein said lock member is movable between said locked position and said unlocked position by said articulation knob, and wherein said first articulation member and said second articulation member are moved in opposite directions to articulate said end effector about said articulation axis when said articulation knob is moved from said unarticulated position toward a said articulated position, characterized in that said lock member comprises a carriage including a protrusion configured to engage said articulation knob, and wherein said carriage surrounds a portion of said articulation knob, wherein said articulation knob comprises a plurality of knob detents, and wherein a said knob detent engages said protrusion and moves said carriage and said lock member proximally when said articulation knob is moved from said unarticulated position toward a said articulated position. a handle; an elongate shaft extending from said handle, wherein said elongate shaft defines a shaft axis; an end effector comprising a plurality of detents; an articulation joint, wherein said end effector is rotatably coupled to said elongate shaft by said articulation joint about an articulation axis; an articulation knob rotatable between an unarticulated position and articulation positions; a first articulation member attached to a first side of said end effector and to said articulation knob; a second articulation member attached to a second side of said end effector and to said articulation knob; and an articulation lock comprising a lock member configured to move between a locked position where said lock member is engaged with a said detent of said end effector and an unlocked position where said lock member is disengaged from said end effector, wherein said lock member is movable between said locked position and said unlocked position by said articulation knob, and wherein said first articulation member and said second articulation member are moved in opposite directions to articulate said end effector about said articulation axis when said articulation knob is moved from said unarticulated position toward a said articulated position, characterized in that said lock member comprises a carriage including a protrusion configured to engage said articulation knob, and wherein said carriage surrounds a portion of said articulation knob, wherein said articulation knob comprises a plurality of knob detents, and wherein a said knob detent engages said protrusion and moves said carriage and said lock member proximally when said articulation knob is moved from said unarticulated position toward a said articulated position.