Interparietal bone

An interparietal bone (os interparietale or Inca bone or os Inca. Var.) is a dermal bone situated between the parietal and supraoccipital.

In humans, it corresponds to the upper portion of the squama of the occipital bone that lies superior to the highest nuchal line and is completely fused to the supraoccipital. However, in some individuals this portion remains separate from the rest of the occipital bone throughout life. In such cases, this separate bone is particularly referred as Inca bone. Inca bones in humans were first found in the skulls of contemporary indigenous peoples of the southern Andes as well as in those of mummies of the Inca civilization. Although the Inca bone was originally encountered as a variation in South American and Latin American cranial remains, the variation occurs in people from all geographic regions of the world and is by no means indicative of South/Latin American origin.