Articular Capsule of Atlantooccipital Joint (Left)

Anatomical Relations

The fibrous layer of the capsule attaches along the margins of the articular surfaces of the atlas and occipital bone, thus, enveloping them. These are the superior articular surfaces of the atlas and the occipital condyles. The condyles are positioned on both sides of foramen magnum.

The fibrous layer blends with the anterior longitudinal ligament on their anteromedial aspects and with the posterior atlantooccipital membrane posteriorly.

The synovial membrane forms the inner portion of the articular capsule and is overlaid by the outer fibrous layer of the capsule. It is in contact with the margins of articular cartilages that are in close proximity to the fibrous layer insertion. They may associate with the posterior aspect of the median atlantoaxial joint.

Function

The fibrous layer adds and maintains the stability of the atlantooccipital joint. It restricts excessive movements of the articulating surfaces by tightening as they move.

The synovial membrane allows for the production and secretion of synovial fluid which helps to lubricate joints and prevent friction during movement. It also provides nutrition to the joint. The membrane also locks in this fluid and prevents leakage out of the capsule.

List of Clinical Correlates

—Atlantooccipital joint subluxation

—Osteoarthritis