The atlanto-occipital articulation (also known as the C0-C1 joint/articulation) is comprised of a pair of condyloid synovial joints that connect the occipital bone (C0) to the first cervical vertebra (atlas/C1).
Each joint is comprised of two concave articular surfaces on the superior aspect of the lateral mass of atlas which articulate with a convex surface on the occipital condyle. The joint is reinforced by fibrous capsules which support each joint. The atlanta facets are tilted medially.
- anterior atlanto-occipital membrane: broad, dense fibrous structure which joins the upper border of the anterior arch of the atlas (C1) to the anterior inferior margin of the foramen magnum; it is a continuation of the anterior longitudinal ligament and prevents excessive neck extension. Laterally it blends with the joint capsule and medially is strengthened by a strong, rounded cord which connects the basilar occipital bone to the anterior atlantal tubercle.
- posterior atlanto-occipital membrane: a broad but thin fibrous membrane which attaches the upper border of the anterior surface of the posterior arch of the atlas (C1) to the posterior margin of the foramen magnum. It is continuous with the posterior atlantoaxial membrane inferiorly (part of the ligamentum flavum) and ligamentum nuchae posteriorly and lies immediately posterior to the spinal dura. Posteriorly lie the suboccipital muscles. The atlantic (V3) portion of the vertebral artery runs anteriorly to pierce the membrane and dura and become the dural (V4) portion.
- tectorial membrane: continuation of the posterior longitudinal ligament from the dens to the anterior aspect of the foramen magnum.
The joint capsule is innervated by the C1 nerve.
Anastomosis between the deep cervical, occipital and vertebral arteries.
Allows for 25o of flexion/extension and around 5o of axial rotation.
posterior - vertebral artery
anterior - rectus capitis anterior
posteromedial - dorsal ramus of the first cervical nerve and rectus capitis posterior major
- variable degree of communication between the atlanto-occipital joint and the cavity between the dens (odontoid peg) and transverse ligament of the cruciform ligament
- third occipital condyle (condylus tertius) which may articulate with the anterior arch of the atlas, or the dens
- paracondylar process
- occipital condyle hypoplasia
- division of the superior articular facet of the atlas
- atlanto-occipital assimilation
- arcuate foramen - foramen visualized by the atlantic portion of the vertebral artery as it courses through a calcified posterior atlanto-occipital membrane
- atlanto-occipital dissociation (AOD) represents the most common cervical spine injury following a motor vehicle accident and is usually highly unstable with significant neurological morbidity
- 1. Hall GC, Kinsman MJ, Nazar RG et-al. Atlanto-occipital dislocation. World J Orthop. 2015;6 (2): 236-43. doi:10.5312/wjo.v6.i2.236 - Free text at pubmed - Pubmed citation
- 2. Offiah CE, Day E. The craniocervical junction: embryology, anatomy, biomechanics and imaging in blunt trauma. Insights into imaging. 8 (1): 29-47. doi:10.1007/s13244-016-0530-5 - Pubmed
Related Radiopaedia articles
- spinal canal
- cervical spine
- thoracic spine
- lumbar spine
- vertebral body
- neural arch
- transitional vertebrae
- ossification centers
- intervertebral disc
- anterior longitudinal ligament
- posterior longitudinal ligament
- posterior ligamentous complex
- cervical spine ligaments
- iliolumbar ligament
- epidural ligaments
- musculature of the vertebral column
- muscles of the neck
- muscles of the back
- spinal meninges and spaces
- gross anatomy
white matter tracts (white matter)
- corticospinal tract
- anterolateral columns
- lateral columns
- dorsal columns
- grey matter
- nerve root
- central canal
- functional anatomy
- spinal cord blood supply
- sympathetic chain