Left lateral exposure of orbit, infratemporal fossa, and middle fossa. Extensive bony and selective soft tissue removal displays multiple structures and compartments in this image. For orientation, anterior is toward the left border; superior is toward the upper border of the image. Near the right border can be seen the Gasserian (sensory) ganglion of the trigeminal nerve system. From it arises the ophthalmic nerve (CNV1) to the orbit, the maxillary nerve (CNV2) to the pterygopalatine fossa, and the mandibular nerve (CNV3) to the infratemporal fossa. Deep to the ganglion and the ophthalmic nerve is the internal carotid artery (ICA) as it courses through the carotid canal and cavernous sinus. The abducens nerve (CNVI) enters the cavernous sinus along the lateral surface of the ICA while the oculomotor (CNIII), trochlear (CNIV), and ophthalmic nerves course within the lateral wall (removed) of this sinus. Together, each of these nerves enters the apex of the orbit through the superior orbital fissure. The globe or eyeball is located in the anterior part of the orbit. The optic nerve (CNII) leaves it posteriorly. Adjacent to it is the ophthalmic artery, a branch of the ICA, that supplies the globe and orbital contents. It gives rise to the lacrimal artery that travels to the lacrimal gland located in the superolateral quadrant of the orbit. It also gives rise to several short posterior ciliary arteries that enter the sclera around its junction with the optic nerve. The maxillary nerve exits the middle fossa floor via the foramen rotundum to enter the pterygopalatine fossa. Here it "suspends" the pterygopalatine ganglion, a parasympathetic ganglion, by ganglionic branches. The major nerve to this ganglion is the greater superficial petrosal nerve, a branch of the facial nerve. Postganglionic parasympathetic fibers from this ganglion are involved in secretomotor supply to the lacrimal gland and glands within the nasal and oral cavities. The major continuation of the maxillary nerve is the infraorbital nerve, which enters the floor of the orbit via the inferior orbital fissure. It is accompanied by the infraorbital artery, a branch of the maxillary artery. The greater palatine nerve is also a branch of the maxillary nerve and it descends within the greater palatine canal in company with the descending palatine artery (a branch of the maxillary artery) to the hard palate. The mandibular nerve passes though the roof of the infratemporal fossa via foramen ovale and gives rise to several branches, including the buccal, lingual, inferior alveolar, and auriculotemporal nerves. The maxillary artery traverses the infratemporal fossa contributing several branches in its course, including the middle meningeal artery (which passes through the foramen spinosum to enter the middle fossa). It gives rise to the posterior superior alveolar artery, which enters through foramina on the posterior surface of the maxilla before entering the pterygopalatine fossa via the pterygomaxillary fissure. Here it gives rise to its terminal branches, including the sphenopalatine artery to the nasal cavity. (Image courtesy of M Nunez)