The dens (odontoid process) is a conical projection that arises from the superior surface of the vertebral body of C2 (axis).  It may be tilted posteriorly, anteriorly or laterally with respect to the vertebral body.  The posterior surface is grooved for the transverse band of the cruciform ligament (transverse ligament of atlas), above which is the head.  The anterior surface has an ovoid facet for articulation with the facet on the posterior aspect of the anterior arch of C1 (atlas).  The apical ligament attaches to the pointed apex whereas the alar ligaments attach to ovoid flattenings on the postero-lateral aspect of the apex of the dens.  At the junction of the body and vertebral arch are large ovoid flat or slightly convex superior articular facets for articulation with the inferior articular facets of C1 (atlas) at the atlanto-axial joint.