Inferior view of the clivus through the foramen magnum. Both occipital condyles are present which articulate with the atlas. Just superior to the condyle is the hypoglossal canal, through which the hypoglossal nerve and an arterial branch from the ascending pharyngeal artery traverse. The petrous temporal bones articulate with the clivus in the petroclival fissure, where the inferior petrosal sinus courses. Lateral to the occipital condyles are the mastoid processes. (Image courtesy of AL Rhoton, Jr.)