Part of the cranium, the clivus is a shallow depression behind the dorsum sellC& that slopes obliquely backward. It forms a gradual sloping process at the anterior most portion of the basilar occipital bone at its junction with the sphenoid bone. On axial planes, it sits just posterior to the sphenoid sinuses. Just lateral to the clivus bilaterally is the foramen lacerum which contains the internal carotid artery, proximal to its anastamosis with the Circle of Willis. Posterior to the clivus is the basilar artery. The clivus supports the upper part of the pons. [ http://en.wikipedia.org/wiki/Clivus_(anatomy) ]