Quick Facts
Origin: Midbrain.
Course: Runs from the dorsal midbrain anteriorly, through the superior orbital fissure, and into the orbit.
Branches: None.
Supply: Motor innervation to the superior oblique muscle.
Related parts of the anatomy
Origin
The trochlear nerve originates from the nucleus of the trochlear nerve in the midbrain. Its fibers decussate across the median plane of the brainstem. Thus, it is the only cranial nerve to run contralaterally relative to its nucleus.
Course
The trochlear nerve emerges from the dorsal midbrain just inferior to the inferior colliculus. It runs anteriorly, piercing the dura covering the apex of the petrous portion of the temporal bone, roughly between the trigeminal and oculomotor nerves. It runs through the superior orbital fissure to enter the orbit. Running medial to the frontal nerve, the trochlear nerve turns medially and innervates the belly of the superior oblique muscle.
Branches
There are no named branches.
Supplied Structures
The trochlear nerve is a motor nerve. It innervates only one target, the superior oblique muscle of the eye.
List of Clinical Correlates
—Diplopia
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Anatomy of the oculomotor (CN III), trochlear (CN IV) and abducens (CN VI) nerves
Anatomy of the oculomotor (CN III), trochlear (CN IV) and abducens (CN VI) nerves Videos, Flashcards, High Yield Notes, & Practice Questions. Learn and reinforce your understanding of Anatomy of the oculomotor (CN III), trochlear (CN IV) and abducens (CN VI) nerves.
Trochlear Nerve
The trochlear nerve is the fourth cranial nerve and supplies one muscle of the orbit—the superior oblique.
