Also passing through the foramen magnum are the vertebral arteries, the meninges, and the spinal roots of the accessory nerve [XI].
The clivus slopes upward from the foramen magnum. Lateral to the clivus is a groove for the inferior petrosal sinus between the basilar part of the occipital bone and the petrous part of the petromastoid part of the temporal bone (Fig. 8.27).