The posterior longitudinal ligament is a strong, elongated band that extends along most of the spine. It is attached to the posterior surfaces of the vertebral bodies and their respective intervertebral discs, lining the anterior wall of the vertebral canal.

This ligament runs from the body of the axis (C2) (Read more!) to the anterior wall of the sacral canal (Read more!) of the sacrum. Superiorly, it continues as the tectorial membrane (Read more!), which connects the axis to the clivus of the occipital bone. The posterior longitudinal ligament is typically narrower than its anterior analog, the anterior longitudinal ligament.

In the lower thoracic and lumbar spine (Read more!), the posterior longitudinal ligament is wider over the intervertebral discs and narrower over the vertebral bodies. It is also attached to the intervertebral discs more firmly but to the bodies of the vertebrae looser.

In contrast to the anterior longitudinal ligament, the posterior longitudinal ligament consists of two layers:

Superficial layer - connects three or four vertebral bodies;
Deep layer - extends between two vertebrae.

This ligament is also one of the primary spine stabilizers. It limits spinal flexion, enhancing overall stability. Also, the posterior longitudinal ligament reinforces the intervertebral discs.

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Posterior longitudinal ligament