A surgical instrument, comprising: an elongate shaft; a surgical end effector coupled to said elongate shaft by an articulation joint, wherein said articulation joint is configured to facilitate selective articulation of said surgical end effector relative to said elongate shaft, and wherein said surgical end effector comprises: a first jaw; a second jaw, wherein said second jaw is configured to move relative to said first jaw between an open position and a closed position; and a firing member supported for axial travel within said surgical end effector between a starting position and an ending position, and wherein said surgical instrument further comprises: an upper flexible spine assembly attached to a top portion of said firing member, said upper flexible spine assembly comprising an upper series of upper vertebra members that are loosely coupled together by an upper flexible coupler member that extends through each of the upper vertebra members and is attached to a top of the firing member; a lower flexible spine assembly attached to a bottom portion of said firing member, said lower flexible spine assembly comprising a lower series of lower vertebra members that are loosely coupled together by a lower flexible coupler member that extends through each of the lower vertebra members and is attached to a bottom of the firing member; a rotary drive configured to move said firing member between said starting position and said ending position, said rotary drive comprising a rotary drive screw configured to drivingly interface with the upper series of upper vertebra members and the lower series of lower vertebra members; wherein the articulation joint comprises a movable exoskeleton, wherein said movable exoskeleton comprises a series of movably interfacing annular rib members, wherein each said movably interfacing annular rib member comprises a proximal end and a distal end, wherein said proximal end of one said movably interfacing annular rib member is configured to movably interface with said distal end of an adjacent said movably interfacing annular rib member to facilitate relative movement therebetween in multiple directions, wherein each said movably interfacing annular rib member comprises a central opening, and wherein said central opening in each said movably interfacing annular rib member in said series of movably interfacing annular rib members cooperate to form a passage through said series of movably interfacing annular rib members for receiving a portion of said rotary drive therethrough. an elongate shaft; a surgical end effector coupled to said elongate shaft by an articulation joint, wherein said articulation joint is configured to facilitate selective articulation of said surgical end effector relative to said elongate shaft, and wherein said surgical end effector comprises: a first jaw; a second jaw, wherein said second jaw is configured to move relative to said first jaw between an open position and a closed position; and a firing member supported for axial travel within said surgical end effector between a starting position and an ending position, and wherein said surgical instrument further comprises: a first jaw; a second jaw, wherein said second jaw is configured to move relative to said first jaw between an open position and a closed position; and a firing member supported for axial travel within said surgical end effector between a starting position and an ending position, and wherein said surgical instrument further comprises: an upper flexible spine assembly attached to a top portion of said firing member, said upper flexible spine assembly comprising an upper series of upper vertebra members that are loosely coupled together by an upper flexible coupler member that extends through each of the upper vertebra members and is attached to a top of the firing member; a lower flexible spine assembly attached to a bottom portion of said firing member, said lower flexible spine assembly comprising a lower series of lower vertebra members that are loosely coupled together by a lower flexible coupler member that extends through each of the lower vertebra members and is attached to a bottom of the firing member; a rotary drive configured to move said firing member between said starting position and said ending position, said rotary drive comprising a rotary drive screw configured to drivingly interface with the upper series of upper vertebra members and the lower series of lower vertebra members; wherein the articulation joint comprises a movable exoskeleton, wherein said movable exoskeleton comprises a series of movably interfacing annular rib members, wherein each said movably interfacing annular rib member comprises a proximal end and a distal end, wherein said proximal end of one said movably interfacing annular rib member is configured to movably interface with said distal end of an adjacent said movably interfacing annular rib member to facilitate relative movement therebetween in multiple directions, wherein each said movably interfacing annular rib member comprises a central opening, and wherein said central opening in each said movably interfacing annular rib member in said series of movably interfacing annular rib members cooperate to form a passage through said series of movably interfacing annular rib members for receiving a portion of said rotary drive therethrough.