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Tectorial Membrane

The tectorial membrane is a strong, broad ligament located at the craniovertebral junction, extending from the posterior surface of the body of the axis (C2) to the internal surface of the occipital bone. It is considered the superior extension of the posterior longitudinal ligament and plays a critical role in stabilizing the upper cervical spine. Understanding its anatomy, function, and imaging appearance is essential for radiologists, neurosurgeons, and spine specialists, particularly in the evaluation of trauma, ligamentous injury, or craniovertebral instability.

Synonyms

  • Atlanto-occipital ligament

  • Superior extension of posterior longitudinal ligament

  • Craniovertebral junction ligament

  • Membrana tectoria

Function

  • Stabilizes the craniovertebral junction by preventing excessive flexion of the skull on the cervical spine

  • Limits posterior displacement of the odontoid process (dens) relative to the foramen magnum

  • Contributes to overall spinal ligamentous integrity and protection of the spinal cord at the upper cervical levels

  • Serves as a critical landmark for surgical and radiological assessment of craniovertebral junction injuries

MRI Appearance
T1-weighted images:

  • The tectorial membrane appears as a linear low-to-intermediate signal intensity band posterior to the dens and anterior to the spinal canal CSF

  • Surrounded by hyperintense fat in the prevertebral and paraspinal spaces, providing natural contrast

  • Ligament thickening or injury may appear as focal hypointense thickening or irregularity

T2-weighted images:

  • Normal tectorial membrane remains low signal intensity, sharply outlined against hyperintense CSF in the spinal canal

  • Edema, ligamentous injury, or hematoma may appear hyperintense, highlighting pathology

  • Useful for evaluating ligament disruption or traumatic injury

STIR (Short Tau Inversion Recovery):

  • Suppresses surrounding fat, making subtle ligamentous edema or injury more conspicuous

  • Normal ligament remains low signal, while trauma or inflammation appears bright hyperintense

CT Appearance

  • The tectorial membrane itself is not directly visualized on CT, but its presence and integrity are inferred from the alignment of the dens, atlas, and occiput

  • Surrounding bony structures, including C2 body, odontoid process, atlas, and occipital bone, are clearly visible

  • CT is useful for evaluating fractures, bony malalignment, and craniovertebral junction stability, which indirectly reflects tectorial membrane integrity

MRI images

Tectorial Membrane mri axial image

MRI images

Tectorial Membrane mri sag image