Posterior longitudinal ligament
The posterior longitudinal ligament is situated within the vertebral canal, and extends along the posterior surfaces of the bodies of the vertebrae, from the body of the axis, where it is continuous with the tectorial membrane of atlanto-axial joint, to the sacrum. The ligament is thicker in the thoracic than in the cervical and lumbar regions. In the thoracic and lumbar regions, it presents a series of dentations with intervening concave margins.
The posterior longitudinal ligament is narrow at the vertebral bodies, where it covers the basivertebral veins, and widens at the intervertebral disc space. It weakly prevents hyperflexion of the vertebral column and limits spinal disc herniation, although it is much narrower than the anterior longitudinal ligament, such that spinal disc herniations usually occur in a posterolateral direction.
This ligament is composed of smooth, shining, longitudinal fibers, denser and more compact than those of the anterior ligament, and consists of superficial layers occupying the interval between three or four vertebræ, and deeper layers which extend between adjacent vertebrae.Additional images
