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Interspinous ligament

The interspinous ligament is a thin, fibrous band that connects the adjacent spinous processes of vertebrae along their entire length, extending from the root to the apex of the spinous processes. It lies deep to the supraspinous ligament and posterior to the ligamentum flavum, forming part of the posterior ligamentous complex of the spine. This ligament contributes to stabilization of vertebral segments, limiting flexion and rotational movements, and serves as an attachment site for paraspinal muscles and soft tissues.

The thickness of the interspinous ligament varies by spinal region: thin and membranous in the cervical spine, moderately thick in the thoracic spine, and thicker and stronger in the lumbar spine. Degeneration, trauma, or ligamentous tears can compromise spinal stability and may be associated with chronic back pain or injury.

Function

  • Limits excessive flexion of the vertebral column

  • Stabilizes adjacent vertebrae during motion

  • Provides attachment for paraspinal muscles and fascia

  • Contributes to the posterior ligamentous complex, maintaining spinal integrity

  • Helps prevent posterior displacement of vertebrae

Synonyms

  • Ligamentum interspinale

  • Interspinous fibrous ligament

  • Posterior interspinous ligament

MRI Appearance

T1-weighted images:

  • Appears as a thin low signal (hypointense) linear band connecting spinous processes

  • Surrounded by high signal fatty tissue and marrow in adjacent spinous processes

  • Degenerative changes or tears may appear as focal increased signal due to fibrosis or inflammation

T2-weighted images:

  • Normally low signal intensity (hypointense) due to dense collagen fibers

  • Degenerative or injured ligaments may show hyperintense linear or focal areas, especially if associated with edema or inflammation

  • Provides clear contrast with adjacent marrow and soft tissues

STIR (Short Tau Inversion Recovery):

  • Ligament remains low signal

  • Edema, inflammation, or partial tears appear hyperintense, aiding in detection of acute injuries

T1 Post-Contrast (Gadolinium-enhanced):

  • Normal interspinous ligament shows no enhancement

  • Pathological conditions such as ligamentous tear, inflammation, or infection may demonstrate enhancement along fibers

CT Appearance:

  • The interspinous ligament is not directly visualized on conventional CT, but indirect signs such as widening of interspinous space, fracture displacement, or calcifications may be seen

  • CT is most useful for assessing associated bony injury or ossification of the ligament in chronic conditions

  • Axial and sagittal reconstructions help evaluate posterior spinal elements and canal integrity

MRI images

Interspinous ligament mri sag image -img-00000-00000

MRI images

Interspinous ligamentm mri sag image

CT image

Interspinous ligament ct sagittal image