Anterior atlantooccipital membrane

The anterior atlantooccipital membrane (anterior atlantooccipital ligament) is a broad, dense membrane extending between the anterior margin of the foramen magnum (superiorly), and (the superior margin of ) the anterior arch of atlas (inferiorly). 

The membrane helps limit excessive movement at the atlanto-occipital joints. 

Structure
It is composed of broad, densely woven fibers; especially towards the midline  where the membrane is continuous medially with the anterior longitudinal ligament.  It is innervated by the cervical spinal nerve 1. 

Relations
Medially, it is continuous with the anterior longitudinal ligament.  Laterally, it is blends with either articular capsule.

This membrane is in relation in anteriorly with the rectus capitis anterior muscles, and posteriorly with the alar ligaments.