Posterior Atlantooccipital Membrane as, Posterior View

Description

Spanning between the posterior margin of the foramen magnum of the occipital bone and the posterior arch of the atlas (C1), the posterior atlantooccipital membrane is presented in posterior aspect as a thin ligamentous sheet closing the atlantooccipital interval. Laterally, it is pierced by the vertebral artery after it exits the transverse foramen of C1 and grooves the superior surface of the posterior arch before turning anteriorly toward the dura and cranial cavity. Surrounding bony landmarks include the external occipital crest and adjacent nuchal lines superiorly, with the C2 spinous process and laminae lying inferior to the atlas. Midline stability structures sit deeper. That lateral arterial perforation matters. The vertebral artery is vulnerable during posterior approaches to the craniovertebral junction and during C1 lateral mass screw placement, where dissection or instrument trajectory near the posterior arch can endanger the V3 segment. This view also clarifies why the posterior atlantooccipital membrane, sometimes termed the posterior atlantooccipital ligament, can form a fibrous or ossified arcuate foramen (Kimmerle anomaly) that contributes to vertebrobasilar insufficiency symptoms or neck rotation related headache in select patients. A small space. High stakes. Use this artwork for gross anatomy lab teaching of the suboccipital region, spine surgery atlases covering C0 to C2 exposure, and radiology correlation when explaining CTA or MRA findings around the vertebral artery groove of C1. It also fits chiropractic and physical therapy materials discussing cervicogenic headache and vertebral artery safety screening during end range rotation. Anatomical accuracy verified by SciePro's Medical Advisory Board.