Interparietal bone
| Interparietal bone | |
|---|---|
 | |
| Multible interparietal bones or inca bones shown in a 20th century anatomical illustration (latin and german terminology). | |
 | |
| Radiograph of the skull showing an interparietal bone between the occiput and parietal bones | |
| Latin | os interparietale os inca |
An interparietal bone (os interparietale or Inca bone or os Inca. Var.[1]) 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.
In many other mammals, this bone is completely fused to the supraoccipital as in humans. However in some mammals (for example, rodents, rabbits, and artiodactyls), this bone remains separate from the supraoccipital bone. Classic comparative anatomy have regarded the interparietal as being lost in various mammalian lineages since the interparietal and supraoccipital fuse with each other in the early ontogenetic period in many mammals, but recent study has shown that its presence is confirmed in all extant mammalian orders, particularly in the embryonic period (Koyabu and others, 2012).