Presence of an articulating condylus tertius on the basilar part of the occipital bone-A rare anatomical abnormality

Normally, in human skulls, the basilar part of the occipital bone presents two occipital condyles which articulate with the superior articular facets of the atlas vertebra. A rare case of third occipital condyle (condylus tertitus) with an additional articular facet on it was observed in a dry skull from South India. The third condyle was on the basilar part of the occipital bone along the anterior margin of the foramen magnum. It showed an additional articular facet which was smooth surfaced and oval in shape measuring 1cm antero-posteriorly and 1.5cm transversely at its maximum width. Available literature on the condylus tertius and its clinical, surgical and radiological importance were discussed.