Relationship Between Each Division of the Clivus and the Neurovascular Complexes in the Posterior Fossa. The upper clival approach exposes the anterior part of the upper neurovascular complex, including the midbrain and adjacent part of the pons, superior cerebellar artery, oculomotor, and trigeminal nerves. The middle clival approach exposes the anterior part of the middle neurovascular complex, including the lower half of the pons, anterior inferior cerebellar artery, abducens, facial, and vestibulocochlear nerves. The lower clival approach exposes the anterior part of the lower neurovascular complex, including the medulla, posterior inferior cerebellar artery, glossopharyngeal, vagal, accessory, and hypoglossal nerves. (Image courtesy of AL Rhoton, Jr.)