Articulating surgical instruments

A surgical instrument comprising:

• a handle;
• and
• an elongated shaft assembly extending distally from the handle, wherein the elongated shaft assembly includes an articulable portion with an articulation direction, the elongated shaft assembly comprising:
• a first tubular member;
• a second tubular member;
• a locking tubular member with a flexible portion with a preferential bending direction and a direction of bending resistance, wherein the direction of bending resistance is parallel to a plane extending between a first spine and a second spine located on opposite sides of the locking tubular member, wherein the first tubular member, the second tubular member, and the locking tubular member are coaxially located, wherein the locking tubular member is moveable relative to the first tubular member and/or the second tubular member, wherein the locking tubular member permits articulation of the elongated shaft assembly when movement of the locking tubular member aligns the plane with the articulation direction, wherein the locking tubular member prevents articulation of the elongated shaft assembly when movement of the locking tubular member relative to the articulable portion misaligns the plane with the articulation direction.

A surgical instrument comprising:

• a handle;
• and
• an elongated shaft assembly extending distally from the handle, the elongated shaft assembly comprising:
• a first tubular member including a first flexible portion with a first plurality of slots and at least a first spine extending along a length of the first flexible portion;
• a second tubular member including a second flexible portion with a second plurality of slots and at least a second spine extending along a length of the second flexible portion;
• and
• a locking tubular member including a third flexible portion with a third plurality of slots, a third spine, and a fourth spine extending along a length of the third flexible portion, wherein the first tubular member, the second tubular member, and the locking tubular member are coaxially located, wherein the first tubular member and the second tubular member are axially fixed relative to one another at a position distal from the first flexible portion and the second flexible portion, and wherein the locking tubular member is rotatable relative to the first tubular member and/or the second tubular member.