Ponticulus posticus of atlas vertebrae: an incidental finding in Malaysian orthodontic patients

Description

Ponticulus posticus is a normal anatomical variant of atlas vertebrae (C1) and resides in the posterior arch of atlas in relation to vertebral artery. It is an incidental finding visualised from lateral cephalograms taken for routine orthodontic treatment purpose. Ponticulus posticus in Latin means 'little posterior bridge'. Other synonyms for ponticulus are arcuate foramen, kimerle anomaly, retroarticular foramen and retocondylar foramen.1 An overall incidence of ponticulus posticus has been reported to be 16.7%. Literature reveals a higher incidence in females compared with males and this anomaly was age independent.2

This additional bone formation is formed by the calcification of posterior-atlanto occipital membrane. Radiographically, three variations are seen in this normal variant according to Miki et al: a complete form, partial form and calcified form of ponticulus posticus.1 The complete form is where the bony ring is fully formed, thus, resembling a foramen....

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