Posterior superior view of the sellar and parasellar regions. The meningeal dura has been removed on the right side to expose the cavernous sinus and the nerves within its lateral wall, including the oculomotor and trochlear nerves. These course toward the superior orbital fissure. The inferior petrosal sinus drains the cavernous sinus and descends in the petroclival groove. Note the entrance of the abducens nerve into the dura mater along the clivus. It ascends and passes deep to the petrosphenoid ligament to enter the cavernous sinus. (Image courtesy of AL Rhoton, Jr.)