Superior view of the posterior fossa and quadrigeminal cistern. For orientation, the tentorium cerebelli has been resected to reveal the underlying sinuses. The superior petrosal sinuses course along the petrous ridge from the cavernous sinus to the junction of the transverse and sigmoid sinuses. The midbrain has been transected to reveal the crus cerebri, red nuclei and substantia nigra of the midbrain along with the cerebral aqueduct. Branches of the superior cerebellar arteries course through the cerebellomesencephalic fissure to supply the superior cerebellum and the midline vermis.  (Image courtesy of AL Rhoton, Jr.)