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Inferior Branch of Oculomotor Nerve
Nervous System

Inferior Branch of Oculomotor Nerve

Ramus inferior nervi oculomotorii

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Quick Facts

Origin: Oculomotor nerve.

Course: Runs inferiorly and anteriorly in the orbit for a short distance.

Branches: Branch to ciliary ganglion.

Supply: Extraocular muscles, sphincter pupillae, and ciliary muscles.

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Origin

The inferior branch of the oculomotor nerve originates within the orbit, anterior to the tendinous ring of the extraocular muscles.

Course

The inferior branch of the oculomotor nerve runs inferiorly and anteriorly in the orbit. It typically splits quickly to form terminal branches; however, the exact branching location in the orbit is highly variable.

Branches

The inferior branch of the oculomotor nerve ramifies, sending somatic motor innervation to the extraocular muscles. A named branch, the branch to the ciliary ganglion, sends parasympathetic fibers to the ciliary ganglion.

Supplied Structures

The inferior branch of the oculomotor nerve is a motor nerve. It supplies somatic motor innervation to three of the extraocular muscles of the eye, including the medial rectus, inferior rectus, and the inferior oblique muscles.

Parasympathetic efferent fibers traveling from the Edinger-Westphal nucleus run through the inferior branch of the oculomotor nerve to the ciliary ganglion onto the eyeball itself. Here they act on the sphincter pupillae and ciliary muscle fibers.

List of Clinical Correlates

—Pupillary light reflex

—Accommodation reflex

—Diplopia

Learn more about this topic from other Elsevier products

Oculomotor Nerve

ScienceDirect image

As the oculomotor nerve exits the midbrain, the parasympathetic fibers are superficial, and as the nerve nears the orbit, the parasympathetic fibers move into the center of the nerve and therefore are better protected in compressive lesions.

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