Absence of Costal Element of the Foramen Transversarium of Atlas Vertebrae: a Case Report

Abstract

We detected an atlas vertebra of which costal elements of its foramen transversarium were not developed bilaterally. The costal elementis an arch of bone that form the anterior portion of foramen transversarium. The vertebral arteries running towards cranial cavity aresurrounded and protected by foramina transversarium of upper six cervical vertebrae. Surgeons should be aware of this variation beforeoperations to neck region, because the vertebral arteries may easily be injured due to lack of anterior bony protection of the costalelements. As well as the vertebral artery, the nerve plexus around vertebral artery may also be responsible of some complications due tofailure of this bony protection.