Squamous part of occipital bone

The squamous part of occipital bone forms the dorsal and caudal part of the occipital bone. It has an exocranial and an endocranial faces.

• On the exocranial surface, there is a transverse protrusion dorsally called the external occipital protuberance. It extends laterally on either side by the nuchal crest. From the external occipital protuberance, the external occipital crest, where the nuchal ligament is inserted, extends medially and ventrally towards the foramen magnum.

• On the endocranial side, the squamous part of occipital bone forms, together with the interparietal bone, the ceiling of the cranium cavity. At the level of the union between the squamous part of occipital bone and the interparietal bone, a transverse elevation forms the internal occipital protuberance which is outlined by another relief belonging to the base of the cerebellum tentorium: the tentorial process. Caudal to the internal occipital protuberance is a broad and shallow depression, the vermiform impression, which responds to the vermis of the cerebellum. Rostral to the medial occipital protuberance, the medial sagittal ridge and two grooves for transverse sinus are observed.