Superior view of interior of posterior half of the skull. Portions of the middle and posterior fossae are in view in this bony specimen. The boundary separating these two fossae is the petrous portion of the temporal bone. The greater wings of the sphenoid contain the foramen ovale and spinosum. The squamous portion of the temporal bone completes the floor of the middle fossa laterally. The body of the sphenoid contains a depression, the hypophyseal fossa, for the pituitary gland. The dorsum sellae and basilar part of the occipital bone form the clivus, the slope of bone anterior to the foramen magnum. The foramen lacerum is a space bounded by the apex of the petrous bone and the greater wing and body of the sphenoid. Its floor is covered by fibrous cartilage in life. On the posterior surface of the petrous bone is the internal acoustic meatus for the facial and vestibulocochlear nerves and labyrinthine artery. The jugular foramen, like the foramen lacerum, is a space between the petrous bone and occipital bone for transmission of the internal jugular vein and cranial nerves IX, X, and XI. Between the margin of the foramen magnum and the jugular foramen is the hypoglossal canal for the hypoglossal nerve. (Image courtesy of AL Rhoton, Jr.)