The ponticulus posticus (PP) or arcuate foramen (AF) is a bony bridge arising from lateral mass of atlas, which transforms the groove of vertebral artery into a canal on posterior arch of atlas. The presence of an AF and its relevance was seen in vertebral artery stretching, dissection, canine impactions, in some unexplained headaches and neck pains.
Objective: The aim is to study the presence of AF in atlas vertebrae, their dimensions, and clinical implications.
Materials and methods: A total of 80 dry atlas vertebra specimens were obtained from the Anatomy Department of Army College of Medical Sciences and North Delhi Municipal Corporation Medical College, Delhi, India, and were studied for the presence and dimensions of the AF and the incidences were compared.
Result and conclusion: In our observational study, the AF was found in 13.75% of specimens. The AF was classified as complete, partial, and bony spicules. The observed dimensions of the complete AF in the present study were comparatively less. Interestingly, in some specimen's minimum thickness of dorsal arch of atlas vertebra was found to be less than the minimum thickness required for the surgical screw placement into the lateral masses. Knowledge about these anatomical variations will be of help to neurosurgeons, radiologists, and general medical practitioners.
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