The spine is a weight-bearing structure.
Movement occurs at the apophyseal joints, which are synovial, and at the intervertebral discs.
These structures are closely related, and disease or deformity of one often affects the other. Lumbar disc lesions usually cuase root syndromes. Pathology Disc protrusions usually occur posterolaterally, because here the annulus fibrosus is no longer reinforced by the posterior longitudinal ligament. Occasionally, pain is produced when there is a tear in the annulus but no protrusion. Disc lesions heal by fibrosis but there is always a risk of recurrence.