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Anterior longitudinal ligament

The anterior longitudinal ligament (ALL) is a strong, fibrous band running along the anterior surfaces of vertebral bodies from the occiput to the sacrum. It consists of dense collagen fibers arranged longitudinally, with variable thickness—thicker in the lumbar region to resist higher compressive forces. The ALL is firmly attached to the anterior vertebral bodies and intervertebral discs, blending with the outer fibers of the annulus fibrosus, which enhances spinal stability and limits hyperextension.

The ligament plays a key role in preventing excessive backward bending of the spine, maintaining vertebral alignment, and stabilizing the intervertebral discs. Its vascularized outer layers allow limited healing in cases of injury, whereas the deeper fibers are relatively avascular.

Function

  • Restricts hyperextension of the spine

  • Maintains vertebral alignment

  • Stabilizes intervertebral discs

  • Contributes to spinal load distribution and posture

  • Provides a surgical landmark in anterior spinal approaches

Synonyms

  • ALL

  • Anterior vertebral ligament

  • Ventral longitudinal ligament

MRI Appearance

T1-weighted images:

  • The ALL appears as a thin, low signal intensity (hypointense) linear band along the anterior vertebral body surfaces

  • Adjacent vertebral bone marrow is high signal, providing contrast

  • Thickening or disruption may indicate degenerative changes, trauma, or ligamentous injury

T2-weighted images:

  • ALL remains low signal intensity (hypointense)

  • Surrounding soft tissue edema or acute injury may show hyperintense signal on T2/STIR sequences

  • Degenerative changes may appear as focal thickening or irregularity

STIR (Short Tau Inversion Recovery):

  • Normal ALL is low signal

  • Edema, inflammation, or injury appears hyperintense, highlighting acute trauma, ligamentous tears, or infection

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal ALL shows minimal to no enhancement

  • Pathological conditions (ligament inflammation, post-traumatic injury, infection, or tumor involvement) demonstrate enhancement, especially in the vascularized outer layers

CT Appearance:

  • The ALL appears as a thin linear soft tissue density along the anterior vertebral bodies

  • Ossification, calcification, or thickening may appear hyperdense, commonly seen in conditions like diffuse idiopathic skeletal hyperostosis (DISH)

  • CT is excellent for evaluating ossification, calcific degeneration, or traumatic avulsion injuries

MRI images

Anterior longitudinal ligament mri axial image -img-00000-00000

MRI images

Anterior longitudinal ligament c spine sag

MRI images

Anterior longitudinal ligament c spine

MRI image

Anterior longitudinal ligament MRI sagittal anatomy image -img-00000-00000

CT image

Anterior longitudinal ligament ct axial image