Posterior Atlantooccipital Membrane
Membrana atlantooccipitalis posterior
Read moreStructure
The posterior atlantooccipital membrane is a sheet of connective tissue that extends from the posterior arch of the atlas to the posterior margin of foramen magnum. Its bony attachments enable it to cover the open space between the atlas and the cranium. The posterior atlantooccipital membrane is wider but thinner than its anterior counterpart.
Related parts of the anatomy
Anatomical Relations
The posterior atlantooccipital membrane corresponds superiorly with the ligamentum flavum Laterally, it blends with the atlantooccipital joint capsules, thickening the joint capsule. Anteriorly, the ligament is adherent to the spinal dura (Zumpano, Hartwell and Jagos, 2006). Posteriorly, it is related to the rectus capitis posterior major muscle. The posterior atlantooccipital membrane, along with the posterior arch of the atlas, forms the floor the suboccipital triangle, which is bounded by small cranially inserted muscles.
The posterior atlantooccipital membrane forms an arc on its insertion to the posterior arch of the atlas, allowing for smooth passage the vertebral artery, first cervical nerve, and venous vessels from the vertebral foramina to the foramen magnum. The margin of this ligamentous arc over these neurovascular structures may be harder and stiffer than the rest of the ligament, which may contribute to reduced obstruction or adhesion to the neurovascular bundle.
Function
Given its median posterior position, the posterior atlantooccipital membrane is in a beneficial position to prevent hyperflexion of the atlas, which it achieves in conjunction with the other locally supporting ligaments.
List of Clinical Correlates
—Cervicogenic headache
References
Zumpano, M. P., Hartwell, S. & Jagos, C. S. (2006) Soft tissue connection between rectus capitus posterior minor and the posterior atlanto-occipital membrane: a cadaveric study. Clin Anat, 19(6), 522-7.
