trochlear nucleus

The trochlear nucleus is located in the caudal midbrain and is part of the general somatic efferent functional component. This nucleus is associated with the trochlear nerve (CN IV), which is unique for exiting the dorsal side of the brainstem. Fibers from the trochlear nucleus cross in the midbrain before exiting, causing the trochlear neurons to innervate the contralateral superior oblique muscle of the eye. This muscle is responsible for rotating the eye downward and slightly outward. Damage to the trochlear nerve can lead to a loss of this eye movement and may cause double vision (diplopia). The trochlear nerve is one of the cranial nerves that supply some of the eye muscles with motor fibers.123