Which cranial nerve controls the movement of the superior oblique muscle?

The trochlear nerve, also known as cranial nerve IV, is responsible for the movement of the superior oblique muscle. This muscle is one of the extraocular muscles that control eye movement, specifically acting to rotate the eye downward and laterally. The trochlear nerve is unique among cranial nerves because it is the only one that innervates a muscle located on the opposite side of its origin, making it critical for coordinated eye movement.

The oculomotor nerve primarily innervates several other extraocular muscles, such as the superior rectus, medial rectus, inferior rectus, and inferior oblique, but it does not control the superior oblique. The abducens nerve is responsible for the lateral rectus muscle, which moves the eye laterally, while the trigeminal nerve does not innervate any extraocular muscles at all; it is primarily responsible for sensation in the face and motor functions such as biting and chewing. Thus, the trochlear nerve is specifically tasked with the control of the superior oblique muscle, making it the correct choice for this question.