The<unk>  originates from the third nerve nucleus at the level of the superior colliculus in the midbrain. The third nerve nucleus is located ventral to the cerebral aqueduct, on the pre-aqueductal grey matter. The fibers from the two third nerve nuclei located laterally on either side of the cerebral aqueduct then pass through the red nucleus. From the red nucleus fibers then pass via the substantia nigra exiting through the interpeduncular fossa. On emerging from the brainstem, the nerve is invested with a sheath of pia mater, and enclosed in a prolongation from the arachnoid. It passes between the superior cerebellar (below) and posterior cerebral arteries (above), and then pierces the dura mater anterior and lateral to the posterior clinoid process, passing between the free and attached borders of the tentorium cerebelli. It traverses the cavernous sinus, above the other orbital nerves receiving in its course one or two filaments from the cavernous plexus of the sympathetic nervous system, and a communicating branch from the ophthalmic division of the trigeminal nerve. As the<unk>  enters the orbit via the superior orbital fissure it then divides into a superior and an inferior branch. Superior branch The superior branch of the<unk>  or the superior division, the smaller, passes medially over the optic nerve. It supplies the superior rectus and levator palpebrae superioris. Inferior branch The inferior branch of the<unk>  or the inferior division, the larger, divides into three branches. * One passes beneath the optic nerve to the medial rectus. * Another, to the inferior rectus. * The third and longest runs forward between the inferior recti and lateralis to the inferior oblique. *From the third one, a short thick branch is given off to the lower part of the ciliary ganglion, and forms its short root. All these branches enter the muscles on their ocular surfaces, with the exception of the nerve to the inferior oblique, which enters the muscle at its posterior border. Nuclei The<unk>  (CN III) arises from the anterior aspect of mesencephalon (midbrain). There are two nuclei for the<unk> : * The<unk>  nucleus originates at the level of the superior colliculus. The muscles it controls are the striated muscle in levator palpebrae superioris and other extraocular muscles except for the superior oblique muscle and the lateral rectus muscle. * The Edinger-Westphal nucleus supplies parasympathetic fibers to the eye via the ciliary ganglion, and thus controls the sphincter pupillae muscle (affecting pupil constriction) and the ciliary muscle (affecting accommodation). Sympathetic postganglionic fibres also join the nerve from the plexus on the internal carotid artery in the wall of the cavernous sinus and are distributed through the nerve, e.g., to the smooth muscle of superior tarsal (Mueller's) muscle.
Oculomotor nerve
Supratrochlear nerve
Olfactory nerve
Buccal branches of the facial nerve
Auriculotemporal nerve
Olfactory trigone
Nerve of pterygoid canal
Optician