An articulatable member includes a distal end, a proximal end, an actuation member, and a constraint member. The actuation member extends from the proximal end to the distal end. The actuation member transmits force to bend the articulatable member from a neutral position. The constraint member extends from the proximal end to the distal end. The constraint member may have opposite ends that are fixed to the distal end and the proximal end. In one embodiment, the constraint member follows a helical path along at least a portion of the articulatable member from the proximal end to the distal end. In another embodiment, the actuation member follows a helical path along at least a portion of the articulatable member.
