Inca bone in forensic autopsy: a report of two cases with a review of the literature.

Complete tripartite and complete asymmetric bipartite bones were, respectively, found in the interparietal region of the occipital bone in two forensic autopsy cases that we encountered. These isolated bones are called the Inca bones, or interparietal bones, which occasionally occur as a result of incomplete fusion of the ossifying nuclei during the developmental course. The Inca bones were detectable on ante-mortem cranial radiographs in these two cases. We review the embryological background of this variation, discuss the significance of this variation in forensic medicine, and additionally, present a review of the frequencies of other non-metrical characteristics of the skulls that may be detectable at the time of autopsy.