The First Cervical vertebra, or Atlas, differs from the typical vertebrae. It consists of a ring of bone supporting laterally, the lateral masses which articulate above with the condyles of the occipital bone, and below with the second cervical vertebra. Posteriorly, it has a rudimentary spine, and on the posterior surface of the anterior arch is a small facet for articulation with the odontoid peg of the axis, or second cervical vertebra. The transverse processes, similar to those of the other cervical vertebrae, are attached to the lateral masses.

Fig. 28. - Atlas.