Lateral view of a left petrosectomy. The tympanic membrane is visible at the depth of the external acoustic meatus, adjacent to the middle ear. The semicircular canals of the inner ear are dissected. The styloid process is deep and inferior to the acoustic meatus. A large occipital artery courses posteriorly, inferior to the mastoid tip, and gives a meningeal branch which courses intracranially near the sigmoid sinus. The facial nerve gives off the chorda tympani which runs superiorly over the external acoustic meatus deep to the tympanic membrane. The internal carotid artery is visible deep to the trochlear nerve and the Gasserian ganglion of the trigeminal nerve. The external carotid artery gives off two major branches visible here - the superficial temporal artery and the maxillary artery. The middle meningeal artery, a branch of the maxillary artery, passes between the roots of the auriculotemporal nerve before entering the foramen spinosum. The auriculotemporal nerve, a branch of the mandibular nerve, runs with the superficial temporal artery and vein over the lateral scalp. The glossopharyngeal, vagus, and spinal accessory nerves are seen deep to the jugular bulb. (Image courtesy of AL Rhoton, Jr.)