The ligaments and anulus fibrosus of human adult cervical intervertebral discs

Study Design. Descriptive, microdissection study. Objective. To determine the morphology of the human adult cervical interver tebral disc and its ligaments. Summary of Background Data. Some studies indicate that the cervical disc is distinctly different from the lumbar Intervertebral disc, yet most clinica l and anatomic texts appear content with extrapolating data from the lumbar spine. A detailed three-dimensional description of the cervical interverte bral disc and its surrounding ligaments is currently unavailable. Methods. Whole cervical spinal columns were freed from 12 human adult embal med cadavers, and the posterior elements and soft tissues were removed. Usi ng microdissection, the longitudinal ligaments and the fibrous components o f 59 cervical intervertebral discs were resected systematically. The orient ation, location, and attachments of each stripped bundle of collagen were r ecorded photographically and in sketches. Results. The cervical anulus fibrosus does not consist of concentric lamina e of collagen fibers as in lumbar :discs. Instead, it forms a crescentic ma ss of collagen thick anteriorly and tapering laterally toward the uncinate processes. It is essentially deficient posterolaterally and is represented posteriorly only by a thin layer of paramedian vertically orientated fibers . The anterior longitudinal ligament covers the front of the disc, and the posterior longitudinal ligament reinforces the deficient posterior anulus f ibrosus with longitudinal and alar fibers. Conclusions. The three-dimensional architecture of the cervical anulus fibr osus is more like a crescentic anterior interosseous ligament than a ring o f fibers surrounding the nucleus pulposus.