Some new observations on the functional anatomy of the lower cervical spine.

The ligaments are a major stabilizing component of the cervical spine and are critical for spinal stability as well as stabilization therapy. Relatively little information is available on the anatomic details and function of the cervical ligaments. Fifteen fresh cervical spines were dissected and the ligaments examined grossly and functionally. Eight different intrinsic ligaments of the lower cervical spine were identified. The largest and most rigid of these are the annulus fibrosus, posterior longitudinal ligament, and capsular ligament. By virtue of their size and certain biomechanical observations, these ligaments stabilize the cervical spine. The other ligaments play a more specialized and secondary role. The intertransverse ligaments, although thin and frail, are consistently found and appear to limit rotation and lateral bending, the anterior longitudinal ligament limits extension and the interspinous and supraspinous ligaments limit spinal flexion. Under physiologic conditions, the elastic ligamentum flavum permits extension of the spine without impinging upon the spinal cord or nerve roots. As a group, the ligaments of the cervical spine control motion within finite limits without jeopardizing spinal cord or nerve root function.