Microsurgical Anatomy of the Oculomotor Nerve

Abstract

The oculomotor nerve supplies the extraocular muscles. It also supplies the ciliary and sphincter pupillae muscles through the ciliary ganglion. The nerve fibers leave the midbrain through the most medial part of the cerebral peduncle and enter the interpeduncular cistern. After the oculomotor nerve emerges from the interpeduncular fossa, it enters the cavernous sinus slightly lateral and anterior to the dorsum sellae. It enters the orbit through the superior orbital fissure, after exiting the cavernous sinus, to innervate the extraocular muscles. Therefore, knowledge of the detailed anatomy and pathway of the oculomotor nerve is critical for the management of lesions located in the middle cranial fossa and the clival, cavernous, and orbital regions. This review describes the microsurgical anatomy of the oculomotor nerve and presents pictures illustrating this nerve and its surrounding connective and neurovascular structures. Clin. Anat. 30:21-31, 2017. © 2016 Wiley Periodicals, Inc.

The Anatomical Relationships of the Ocular Motor Nerves with an Emphasis on Surgical Anatomy of the Orbit

“…Here, it lies lateral and anterior to the dorsum sellae of sella turcica. It passes through the superior orbital fissure after exiting the cavernous sinus and enters the orbit (Park et al, ). The segmental classification of the oculomotor nerves varies from one author to another.…”

“…Most commonly, the nerve is divided into five segments according to its course as: cisternal, petroclinoid, cavernous, fissural, and orbital (Marinkovic and Gibo, ; Zhang et al, ). Most recently, Park et al () have classified the nerve under seven segments being; intramesencephalic, interpeduncular, cisternal, petroclinoid, trigonal, cavernous, fissural, and orbital. Whatever the classification is a detailed knowledge of the anatomy and pathway of the oculomotor nerve and relations with its surrounding connective and neurovascular structures is very important for the management of lesions located in the orbit.…”

“…The superior orbital fissure is the site of blending of the dura, periorbita of the orbital apex, and the annular tendon which give rise to the extraocular muscles. The annular tendon surrounds only the upper‐medial portion of the superior orbital fissure and situated lateral to the optic foramen (Morard et al, ; Park et al, ). The oculomotor nerve passes inside the annular tendon and splits into superior and inferior divisions in oculomotor foramen (Figs.…”

Anatomical study on branching pattern and variations of orbital segment of the oculomotor nerve

“…The CN III provides motor innervation to the levator palpebrae superioris and almost all extraocular muscles except the superior oblique and lateral rectus muscle. It also carries preganglionic parasympathetic fibres to the sphincter pupillae and the ciliary muscles of the eye [1,10,22,24,27]. Those fibres enter the ciliary ganglion through the motor (parasympathetic) root of the ganglion.…”

Teaching Images in Headache: Thrombosis of Posterior Communicating Artery Aneurysm

“…Although headache and oculomotor nerve palsy are an uncommon presentation of unruptured intracranial aneurysm, pupil involvement during headache should prompt intracranial vessel study. Since parasympatethic fibers run in the supero‐medial region of the oculomotor nerve, PCoA aneurysms can produce ipsilateral mydriasis compressing them . Thus, when evaluating patients with migraine in the ED, perform a complete neurological examination, also looking straight into their eyes.…”