Fig. 18 Nerves to the extraocular muscles. The superior and inferior divisions of the oculomotor nerve are separated by the nasociliary nerve within the superior orbital fissure. The superior division supplies the superior rectus and the levator palpebrae superioris muscles. The inferior division supplies the inferior and the medial rectus muscles and the inferior oblique muscle. The trochlear nerve supplies the superior oblique muscle, whereas the abducens nerve innervates the lateral rectus muscle. (III, cranial nerve III; IV, cranial nerve IV; VI, cranial nerve VI; SUPIII, superior division of cranial nerve III; INFIII, inferior division of cranial nerve III)