Trochlear Nerve
Description[edit | edit source]
The trochlear nerve (CN IV) is a general somatic efferent (motor) nerve is the smallest cranial nerve, but has the longest intracranial length which innervates a single muscle (superior oblique muscle) on the contralateral side of its origin.
Course[edit | edit source]
The trochlear nerve appears from the dorsal region of the brainstem around the level of caudal mesencephalon below the inferior colliculus, it winds ventrally around the brainstem and stretch forward to the eye through the subarachnoid space. It extends between the superior cerebellar and posterior cerebral arteries, penetrates the dura. It thereafter courses through the lateral wall of the cavernous sinus and joins three other cranial nerves – occulomotor nerve (CN III), abducens nerves (CN VI), as well as the first two branches of the trigeminal nerve (CN V), ophthalmic (V1) and maxillary (V2). They enter the orbit via the superior orbital fissure where the trochlear nerve supplies the superior oblique muscle.
