Deflectable instrument shafts are formed of a plurality of vertebral segments. One embodiment utilizes alternating segments, each of which has a first end or face contacting an adjacent segment along a first plane, and a second end or face contacting an adjacent segment along a second plane that is transverse to the first plane. In some embodiments, the alternating segments are first and second segments having differently shaped contacting ends/faces. In other embodiment the alternating segments are identical to one another but are positioned such that segments having their first contacting end/face facing distally are alternated with segments having their second contacting ends/faces facing distally. In other embodiments, embodiments having semi-spherical articulating surfaces are used.
