Os supra petrosum of Meckel

Attention is called to a little known cranial ossicle, the os supra petrosum (O.S.P.) located within the dura at the tip of the petrous bone. It is an anatomic variant which may be seen quite clearly in the roentgenograms. It is of no apparent clinical significance but should be recognized in the differential diagnosis of intracranial calcifications. Five children with this roentgen finding are reported together with some postmortem observations, both gross and histologic, in 1 of the cases.