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, wherein the elongated shaft assembly comprises: a first tubular member including a first flexible portion including a first plurality of slots and at least a first spine extending along a length of the first flexible portion ; whereby the elongated shaft assembly further comprises: a second tubular member , characterised in that the second tubular member includes a second flexible portion including a second plurality of slots and at least a second spine extending along a length of the second flexible portion , 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 in that the elongated shaft assembly further comprises a third 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 third tubular member are coaxially located, and wherein the third tubular member is rotatable relative to the first tubular member and/or the second tubular member . 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, wherein the elongated shaft assembly comprises: a first tubular member including a first flexible portion including a first plurality of slots and at least a first spine extending along a length of the first flexible portion ; whereby the elongated shaft assembly further comprises: a second tubular member , characterised in that the second tubular member includes a second flexible portion including a second plurality of slots and at least a second spine extending along a length of the second flexible portion , 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 in that the elongated shaft assembly further comprises a third 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 third tubular member are coaxially located, and wherein the third tubular member is rotatable relative to the first tubular member and/or the second tubular member . a first tubular member including a first flexible portion including a first plurality of slots and at least a first spine extending along a length of the first flexible portion ; whereby the elongated shaft assembly further comprises: a second tubular member , characterised in that the second tubular member includes a second flexible portion including a second plurality of slots and at least a second spine extending along a length of the second flexible portion , 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 in that the elongated shaft assembly further comprises a third 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 third tubular member are coaxially located, and wherein the third tubular member is rotatable relative to the first tubular member and/or the second tubular member . <EOS>