Thoracic Posterior Longitudinal Ligament

ligamentum longitudinale posterius thoracicum

The posterior longitudinal ligament in the thoracic spine lines the posterior vertebral bodies within the spinal canal, wider over the disc spaces and narrow over the vertebral bodies, providing the posterior annular support.

Region: Chest

Biomechanics

Function & Actions

Resists hyperflexion and posterior disc herniation, limits excessive anterior translation, and reinforces the posterior annulus fibrosus. The denticulate ligaments of the spinal cord anchor to adjacent structures near this level.

Clinical Relevance

Clinical Notes

Ossification of the posterior longitudinal ligament (OPLL) is more common in the cervical than thoracic spine but produces more devastating myelopathy when thoracic — the smaller thoracic canal provides less reserve. Thoracic OPLL often requires combined anterior-posterior decompression due to its complexity and risk of cord injury.

Pathology

Common Injuries & Conditions

Thoracic OPLL Myelopathy

Ossification of thoracic PLL narrowing the spinal canal and causing progressive myelopathy with spastic paraparesis, treated by staged anterior-posterior decompression and fusion.

Thoracic PLL Disruption in Fracture

Posterior longitudinal ligament tearing in thoracic burst fractures allowing retropulsion of bone fragments into the canal, assessed by MRI for surgical planning.