Anatomical description and frequencies of bony projections on the cerebral aspect of the petromastoid part of the temporal bone in dry adult human skulls.

A morphological peculiarity was observed in the form of bony projections on the upper part of the medial border of the groove for the sigmoid sulcus on the internal surface of the mastoid part of the temporal bones. In a study on 636 temporal regions of 318 dry unsexed adult human skulls of Indian origin, 101 (15.9%) temporal bones exhibited these elevations. These ranged from being inconspicuous tubercles to well-defined sharp spines. In 73 (72.3%) cases, a projection was present unilaterally, more commonly on the right side and in 28 (27.7%) it was bilateral. A subjective assessment of the size showed the projections to be small (70; 69.3%), medium (16; 15.8%) and large (15; 14.8%).