Simultaneous lateral ponticle with facet-like depression and epitransverse process of the atlas

Abstract

The lateral ponticle and epitransverse process are rare anatomical variations found on the atlas vertebra of the cervical spine. When a lateral ponticle occurs, an abnormal bony bridge extends from the superior articular facet to the transverse process. This bony bridge bisects the transverse foramen wherein the vertebral artery normally lies. In this case report, we describe a C1 specimen from an adult male with a lateral ponticle on the right side and an epitransverse process on the left side. Additionally, an articular facet-like structure was also found on the lateral ponticle's surface. Relevant literature regarding the lateral ponticle across age groups, sex, race, and species is also reviewed. We postulate that genesis of the lateral ponticle of the atlas occurs in utero, specifically during the lateral ossification of the ventral sclerotomes. To our knowledge, an articular facet-like structure on such a ponticle has not been reported previously. Moreover, simultaneous occurrence of a lateral ponticle and contralateral epitransverse process has, to our knowledge, not been reported before.