Anatomy
Summary
The third, fourth, and sixth cranial nerves (CN III, IV, VI), referred to as the oculomotor, trochlear, and abducens nerves, innervate the extraocular muscles of the eye; they are responsible for eye movement. They travel along the cavernous sinus before entering the orbit via the superior orbital fissure.
The oculomotor nerve supplies four out of the six extraocular muscles, including: superior rectus, inferior rectus, medial rectus, and inferior oblique. This nerve also supplies the levator palpebrae superioris, controls the involuntary constriction of the pupils via the efferent limb of the pupillary light reflex, and plays a crucial role in accommodation. The trochlear nerve supplies the superior oblique muscle, primarily acting to internally rotate the eye, depressing the eye when looking medially, as well as abduction. The abducens nerve controls the lateral rectus, which abducts the eye.
Lesson Outline
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FAQs
Cranial nerve III, also known as the oculomotor nerve, innervates the superior rectus, inferior rectus, medial rectus, and inferior oblique muscles, which facilitate eye movement along with CN IV and VI. CN III also innervates the levator palpebrae superioris which lifts the upper eyelid. In addition, this nerve is involved in pupillary constriction and accommodation.
The extraocular muscles are responsible for eye movement. The oculomotor nerve innervates four out of the six extraocular muscles, including: superior rectus, medial rectus, inferior rectus, and inferior oblique. The trochlear nerve innervates the superior oblique muscle, and the abducens nerve innervates the lateral rectus muscle.
The cavernous sinus is one of the major dural venous sinuses in the skull. The oculomotor, trochlear, and abducens nerves pass through the cavernous sinus before entering the orbit via the superior orbital fissure.
