Bilateral Posterior and Lateral Ponticles Resulting In the Formation of Vertebral Artery Canal for the Atlas: Case Report

Abstract

Atlas first cervical vertebra having no spine and body differs from other vertebra. Contains two archs anterior and posterior. Posterior arch contains groove for vertebral artery. During routine osteology classes for undergraduate medical students, we observed presence of bilateral posterior and lateral ponticles which are forming canal for vertebral artery on behind and lateral to lateral mass of atlas. Present case report is very rare anomaly which may lead to stenosis of vertebral artery and may be useful for orthopaedics during surgical manipulation of cervical spine. First cervical vertebra called as atlas, which support the globe of the head. The name of the atlas derived from a deity of Greek mythology called atlas. It is ring shaped having two arch anterior and posterior. Atlas differes from other vertebra without body and spine. Contains weight bearing two lateal mass with articular facets. Posterior arch forms 3/5 th of circumference of atlantal ring, having groove called as sulcus arteriae vertebralis which transmits vertebral artery and first cervical nerve. Rarely this groove may be converted into foramen by complete posterior ponticles connecting the superior articular facet to posterior arch. This foramina called by different names as saggitale foramen and atlantal posterior foramen, arcuate foramen,a variant of Kimmerle's anomaly, canalis vertbralis, retroarticular vertebral artery ring, arcuate foramen ,retroarticular canal , and retrocondilar vertebral artery ring, ponticulus posticus. Some times very rarely can see lateral ponticles .These spicule extend from the superior edge of the lateral mass of atlas to posterior root of the transverse process. Presences of bilateral posterior and lateral ponticles are very rare.In this case we are reporting presence of both ponticles bilaterally resulting canal for vertebarl artery.