An articulatable member (270, 300, 600, 1200) for a surgical instrument (141, 142, 240), comprising: a plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615) extending in series from a proximal end link to a distal end link, each pair of adjacent links of the plurality of links being pivotably coupled to form a joint (322, 324, 326, 328, 640, 642, 644, 646) between the pair of adjacent links; an actuation member (290, 320, 364) extending from the proximal end link to the distal end link of the plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615), wherein the actuation member (290, 320, 364, 1220) transmits force to bend the articulatable member (270, 300, 600, 1200) from a neutral position; and a constraint member (330, 332, 334, 336, 630, 632, 643, 636, 1240B) extending from the proximal end link to the distal end link of the plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615); wherein the constraint member (330, 332, 334, 336, 630, 632, 643, 636, 1240B) comprises a first end and a second end opposite the first end, the first end being fixed to the distal end link of the plurality of links and the second end being fixed to the proximal end link of the plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615); and wherein the constraint member (330, 332, 334, 336, 630, 632, 643, 636, 1240B) follows a helical path (366, 400) along at least a portion of the articulatable member (270, 300, 600, 1200) from the proximal end link through one or more links of the plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615) at a position proximate an outer periphery of the one or more links to the distal end link; and wherein the constraint member (330, 332, 334, 336, 630, 632, 643, 636, 1240B) is under tensile force between the first and second ends in a straight configuration of the articulatable member (270, 300, 600, 1200). a plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615) extending in series from a proximal end link to a distal end link, each pair of adjacent links of the plurality of links being pivotably coupled to form a joint (322, 324, 326, 328, 640, 642, 644, 646) between the pair of adjacent links; an actuation member (290, 320, 364) extending from the proximal end link to the distal end link of the plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615), wherein the actuation member (290, 320, 364, 1220) transmits force to bend the articulatable member (270, 300, 600, 1200) from a neutral position; and a constraint member (330, 332, 334, 336, 630, 632, 643, 636, 1240B) extending from the proximal end link to the distal end link of the plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615); wherein the constraint member (330, 332, 334, 336, 630, 632, 643, 636, 1240B) comprises a first end and a second end opposite the first end, the first end being fixed to the distal end link of the plurality of links and the second end being fixed to the proximal end link of the plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615); and wherein the constraint member (330, 332, 334, 336, 630, 632, 643, 636, 1240B) follows a helical path (366, 400) along at least a portion of the articulatable member (270, 300, 600, 1200) from the proximal end link through one or more links of the plurality of links (311, 312, 313, 314, 315, 500, 611, 612, 613, 614, 615) at a position proximate an outer periphery of the one or more links to the distal end link; and wherein the constraint member (330, 332, 334, 336, 630, 632, 643, 636, 1240B) is under tensile force between the first and second ends in a straight configuration of the articulatable member (270, 300, 600, 1200).