Basilar part of occipital bone

The basilar part of occipital bone, also known as the basiocciput, is a quadrilateral-shaped extension of the occipital bone. It forms the anterior boundary of the foramen magnum and stretches forward and upward from the front edge of the foramen magnum.

The lower surface of the basilar part is crucial to the skull's base, creating the roof of the pharynx area. Here, you'll find a significant bony bump called the pharyngeal tubercle, which serves as the attachment point for a longitudinal fibrous band known as the pharyngeal raphe. This structure provides the spot where the three constrictor muscles of the pharynx attach.

The upper surface of the basilar part of occipital bone plays a role in forming the posterior cranial fossa. It moves upward and forward, merging with the posterior aspect of the body of the sphenoid bone. Together, they create a sloping structure known as the clivus. The brainstem sits against this slope.

On its sides, the basilar part of occipital bone meets the petrous part of the temporal bone, bridging the space between the sphenoid's greater wing in the front and the basiocciput in the back. The groove that forms between the petrous bone and the basiocciput contains the inferior petrosal sinus as it flows into the jugular foramen.