Three Dimensional Movements Of The Upper Cervical Spine

Ten fresh cadaveric whole cervical spine specimens (occiput to C7) were studied using well established techniques to document the movements in flexion, extension, left and right lateral bending and left and right axial rotation. Pure moments of maximum 1.5 newton meters were applied incrementally and three dimensional movements of the bones were recorded using stereophotogrammetry. Each moment was applied individually and in a three load/unload cycles. The motion measurements were made on the third load cycle. Parameters of neutral zone, elastic zone and range of motion were computed. Neutral zones for flexion/extension, right/left lateral bending and right/left axial rotation were respectively: 1.1, 1.5 and 1.6 (occiput-C1); and 3.2, 1.2 and 29.6 degrees (C1-C2). Ranges of motion for flexion, extension, lateral bending (one side) and axial rotation (one side) were respectively: 3.5, 21.0, 5.5 and 7.2 degrees (occiput-Cl joint) and 11.5, 10.9, 6.7 and 38.9 degrees (CI-CZ joint). The highest intervertebral motion in the spine was the axial rotation at the Cl-C2 joint, neutral zone constituting 75% of this motion.