Surgical instruments with flexible firing member actuator constraint arrangements

A surgical instrument, comprising:

• an elongate shaft assembly;
• a surgical end effector coupled to said elongate shaft assembly by an articulation joint, wherein said articulation joint is configured to facilitate selective articulation of said surgical end effector relative to said elongate shaft assembly in multiple articulation planes;
• a firing member supported for axial travel within said surgical end effector between a starting position and an ending position;
• and
• a firing system configured to selectively move said firing member between the starting position and the ending position, wherein said firing system comprises:
• an upper flexible firing assembly comprising:
• a flexible upper hollow member comprising an upper proximal end and an upper distal end, wherein said upper proximal end is supported within said elongate shaft assembly for axial travel in two directions, wherein said flexible upper hollow member spans said articulation joint and said upper distal end is fixed to said surgical end effector;
• and
• a flexible upper push coil operably interfacing with a source of axial drive motions, wherein said flexible upper push coil is slidably constrained in said flexible upper hollow member for axial movement therein, wherein said flexible upper push coil spans said articulation joint inside of said flexible upper hollow member and operably interfaces with an upper portion of said firing member to apply upper axial drive motions thereto to move said firing member from the starting position to the ending position, and wherein said firing system further comprises:
• a lower flexible firing assembly comprising:
• a flexible lower hollow member comprising a lower proximal end and a lower distal end, wherein said lower proximal end is supported within said elongate shaft assembly for axial travel in the two axial directions, wherein said flexible lower hollow member spans said articulation joint and said lower distal end is fixed to said surgical end effector, wherein said upper proximal end of flexible upper hollow member and said lower proximal end of said flexible hollow lower member are configured to move equal distances relative to each other in opposite axial directions when said surgical end effector is articulated relative to said elongate shaft assembly;
• and
• a flexible lower push coil operably interfacing with said source of axial drive motions, wherein said flexible lower push coil is slidably constrained in said flexible lower hollow member for axial movement therein, wherein said flexible lower push coil spans said articulation joint inside of said flexible lower hollow member and operably interfaces with a lower portion of said firing member to apply lower axial drive motions thereto to move said firing member from the starting position to the ending position.