Relationship of nerves in the right cavernous sinus. The meningeal and periosteal dura have been removed over the lateral wall of the cavernous sinus and floor of middle fossa. The sensory root of the trigeminal nerve has been reflected to expose the motor root of this nerve. The ophthalmic and maxillary branches of the trigeminal nerve are sensory only; the mandibular nerve is mixed. Its sensory root unites with the motor root as they pass through foramen ovale into the infratemporal fossa. Entering the edge of the tentorium cerebelli attachment to the anterior and posterior clinoid processes are the oculomotor and trochlear nerves (the former located superior to the trochlear nerve). Inferior to the trochlear nerve is the ophthalmic nerve. All three of these nerves course within the lateral wall of the cavernous sinus before entering the orbit through the superior orbital fissure, a space between the lesser and greater wings of the sphenoid. The abducens nerve follows these nerves into the orbit after first passing within the sinus along the lateral surface of the cavernous segment of the internal carotid artery. The maxillary nerve is shown entering the foramen rotundum and courses to the pterygopalatine fossa. The greater superficial petrosal nerve is shown leaving its hiatus on the anterior surface of the petrous bone and passing deep to the trigeminal ganglion. The optic nerve enters the optic canal on the medial aspect of the anterior clinoid process. (Image courtesy of AL Rhoton, Jr.)