[TA] the third cranial nerve, it supplies all the extrinsic muscles of the eye, except the lateral rectus and superior oblique; it also supplies the levator palpebrae superioris and conveys presynaptic parasympathetic fibers to the ciliary ganglion for innervation of the ciliary muscle and sphincter pupillae; its origin is in the midbrain below the cerebral aqueduct; it emerges from the oculomotor sulcus of the mesencephalon in the interpeduncular fossa, pierces the dura mater to the side of the posterior clinoid process, passes in the lateral wall of the cavernous sinus, and enters the orbit through the superior orbital fissure. SYN: nervus oculomotorius [CN III] [TA], motor oculi, oculomotorius, third cranial nerve [CN III].