[1] There is a pivot articulation between the odontoid process of the axis and the ring formed by the anterior arch and the transverse ligament of the atlas.

Because of its proximity to the brain stem and importance in stabilization, fracture or injury to the atlanto-axial joint can cause serious problems.

Posterior atlanto-occipital membrane: genetic traits can sometimes result in ossification, turning the groove into a foramen.

[5] This involves classic pathophysiology, such as loss of articular cartilage, osteophytes visible with radiography, and bone thickening with a narrow joint space.

[5] A widening of the atlanto-axial joint, as measured between the posterior surface of the anterior arch of atlas and the front of the odontoid process, indicates an injury to the transverse atlantal ligament.