Superior Articular Surface Of Atlas, Posterior View

Description

Atlas (C1) fills the frame in posterior perspective, centering on the kidney-shaped superior articular surface (facies articularis superior) that accepts the occipital condyle. The facet sits on the superior aspect of the lateral mass, lateral to the vertebral foramen and medial to the transverse process and transverse foramen, with its long axis oriented anteroposteriorly. From this fixed posterior viewpoint, the posterior arch and posterior tubercle lie inferior to the facet margin, while the bony rim of the lateral mass forms a distinct perimeter around the articular cartilage bed. Edges matter here. This articular surface defines the biconvex atlanto-occipital joint, where flexion and extension of the head occur while rotation is largely constrained, and subtle asymmetry or osteophyte formation at the facet can correlate with cervicogenic headache or reduced nodding range. Posterior orientation helps when teaching the relationship between the lateral mass and the groove for the vertebral artery on the superior surface of the posterior arch, a landmark relevant during posterior C1 screw placement and in avoiding vertebral artery injury. The kidney-shaped contour also provides a practical reference when discussing congenital occipitalization of the atlas, rheumatoid pannus with craniovertebral junction instability, or Jefferson burst fracture patterns that can displace the lateral masses relative to the occipital condyles. Medical educators can place this illustration into gross anatomy lab manuals, spine modules, and neuroanatomy courses to reinforce craniovertebral joint surfaces and terminology from Terminologia Anatomica. It also supports figure panels for surgical atlases and radiology teaching files when correlating osseous landmarks with CT bone windows of the upper cervical spine. Anatomical accuracy verified by SciePro's Medical Advisory Board.