atlantooccipitalleden

Atlantooccipital joints, or atlantooccipital articulations, are the pair of synovial joints between the occipital bone at the base of the skull and the first cervical vertebra (the atlas, C1). They form the primary connections at the craniovertebral junction, allowing the head to sit atop the spine while enabling movement.

Anatomy and structure: Each joint is a condyloid (ellipsoid) synovial joint. The superior articular facets of the atlas articulate with the occipital condyles. The joint capsule surrounds the articulation and is reinforced by the anterior and posterior atlantooccipital membranes. Stabilizing ligaments include the alar ligaments, which extend from the dens to the occipital condyles, and the transverse ligament of the atlas as part of the cruciate ligament complex, with the tectorial membrane continuing from the posterior longitudinal ligament over the dens to the occipital region.

Movement and function: The primary motions are flexion and extension of the head (nodding), with the joints permitting a limited degree of lateral flexion. These movements are guided by the shape of the articulating surfaces and restrained by the surrounding ligaments, capsule, and muscular attachments in the suboccipital region.

Innervation and blood supply: The joints are innervated primarily by the suboccipital nerve (dorsal ramus of C1), with potential contributions from adjacent cervical nerves. Blood supply arises from branches of the vertebral and occipital arteries.

Clinical relevance: Disorders at the atlantooccipital joints are uncommon but can be significant. Congenital anomalies such as atlas assimilation (occipitalization) or basilar invagination can affect stability. Acute injuries (rare dislocations) and inflammatory or degenerative conditions can compromise joint stability and cause neck pain or neurologic risk if misalignment occurs.