Question #513
The oculomotor nerve
The oculomotor nerve originates from the oculomotor nucleus located adjacent to the peri-aqueductal grey in the midbrain. In addition, parasympathetic fibres from the Edinger-Westphal nucleus are carried on the nerve.
The oculomotor nerve passes anteriorly through the lateral wall of the cavernous sinus, the superior orbital fissure and then the tendinous ring of the orbit. Just before entering the superior orbital fissure the nerve divides into superior and inferior branches. The superior branch supplies superior rectus and the striated muscle component of levator palpebrae superioris. The inferior branch supplies inferior rectus, inferior oblique and medial rectus. In addition the inferior branch carries parasympathetic fibres to the ciliary ganglion which eventually supply the sphincter pupillae and ciliary muscles.
