In this article, we illustrate and briefly describe a medial approach, in the sagittally sectioned preserved human brain, to display the oculomotor nerve, in situ and in continuity. The method has been successfully used by Milanes-Rodriguez for several cohorts of our second-year medical students, and can be completed within a 90-min dissecting session. We also review the most common clinical manifestation of oculomotor disorder Introduction Despite congenital anomaly of oculomotor nerve is a rare condition some reports about oculomotor disorders due to nerve fenestration [1,2,3], abnormal course [4], hypoplasia in congenital fibrosis of the extraocular muscles [5,6,7], in Duane-Radial Ray Syndrome [8] in congenital extraocular muscle misinnervation [9], among others have been published [10,11,12,13,14]The third, fourth, and sixth cranial nerves innervate the extraocular muscles that position the globes in the orbits. Extraocular muscle paralysis resulting from destructive lesions in one or all of these cranial nerves results in failure of one or both eyes to rotate in concert with the other eye.CN III is the only cranial nerve with a subnuclear complex that arises in the dorsal mesencephalon at the level of the superior colliculus. Fascicles pass through the parenchyma of the midbrain via the red nucleus and corticospinal tract. They exit the mesencephalon and emerge into the subarachnoid space between the cerebral peduncles.The primary symptom is diplopia from misalignment of the visual axes, and the pattern of image separation is the key to diagnosing which particular cranial nerve (and extraocular muscle) is involved. With unilateral third cranial nerve palsy, the involved eye usually is deviated down and out (infraducted, abducted), and there is ptosis, which may be severe enough to cover the pupil. In addition, pupillary dilatation can cause symptomatic glare in bright light (if the ptotic lid does not cover the pupil), and paralysis of accommodation causes blurred vision for near objects [12,15,16,17,18].The oculomotor nerve arises from the anterior aspect of mesencephalon (midbrain). There are two nuclei for the oculomotor nerve: The oculomotor nucleus originates at the level of the superior colliculus. The muscles it controls are the ciliary muscle (affecting accommodation), and all extraocular muscles except for the superior oblique muscle and the lateral rectus muscle. The Edinger-Westphal nucleus supplies parasympathetic fibres to the eye via the ciliary ganglion, and thus controls pupil constriction. On emerging from the brain, 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 in front of and lateral to the posterior clinoid process, passing between the free and attached borders of the tentorium cerebelli.It runs along the lateral wall of the cavernous sinus, above the other orbital nerves, receiving in its course one or two filaments from the cavernous plexus of the sympathetic, and a communicating branch from the ophthalmic division of the trigeminal.It then divides into two branches, which enter the orbit through the superior orbital fissure, between the two heads of the lateral rectus.Here the nerve is placed below the trochlear nerve and the frontal and lacrimal branches of the ophthalmic nerve, while the nasociliary nerve is placed between its two rami: superior branch of oculomotor nerve inferior branch of oculomotor nerve As mentioned before the oculomotor nerve or cranial nerve number III is one of the cranial nerve that together with the trochlear (IV) and abducent (VI) supplies the extra ocular muscles that position the globes in the orbital cavity. Extraocular muscles paralyses result in failure of one eye to rotate in concern with the other producing misalignment of the visual axis with the resulting diplopia as a primary symptom[19
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