Which nerve is responsible for motor control of eye movement and is also known as cranial nerve IV?

The nerve that is responsible for motor control of eye movement, specifically known as cranial nerve IV, is the trochlear nerve. This nerve innervates the superior oblique muscle of the eye, which allows for the downward and lateral movement of the eyeball. It plays a crucial role in coordinating eye movements, particularly when the gaze is directed downward, such as when reading or looking down at an object.

In addition to this functional role, the trochlear nerve is unique among cranial nerves because it is the only one that crosses to the opposite side of the brainstem before innervating its target muscle. This structural aspect contributes to its identification as cranial nerve IV. Understanding this specificity helps clarify the distinctions between the cranial nerves involved in eye movement and reinforces the functions associated with each nerve.