any structural anomaly of the strong, broad fibrous band that covers and connects the anterolateral aspects of the vertebral bodies and intervertebral (IV) discs; this ligament extends from the pelvic surface of the sacrum to the anterior tubercle of vertebra C1 (atlas) and the occipital bone anterior to the foramen magnum; it prevents hyperflexion of the vertebral column, maintaining stability of the joints between the vertebral bodies; it is the only ligament that limits extension; all other ligaments of the vertebral column, like the IV ligaments, limit forms of flexion