Which cranial nerve is responsible for the dorsal oblique muscle?

The correct answer highlights that cranial nerve four (CN 4), also known as the trochlear nerve, is specifically responsible for innervating the dorsal oblique muscle of the eye. This muscle plays a crucial role in eye movement, particularly in depression and intorsion (internal rotation) of the eye.

The dorsal oblique muscle is unique among the extraocular muscles because it originates from the back of the orbit and has a tendinous pulley that allows for a distinctive range of motion. CN 4's function is vital for coordinating eye movements and maintaining proper alignment of the visual axis.

In the context of the other cranial nerves listed, while they also play important roles in eye function, they do not innervate the dorsal oblique muscle. For instance, CN 2 is primarily responsible for vision, CN 3 (oculomotor nerve) innervates most of the extraocular muscles except the lateral rectus and the dorsal oblique, and CN 6 (abducens nerve) solely innervates the lateral rectus muscle, which abducts the eye. Each of these nerves contributes to overall eye movement, but the specific innervation of the dorsal oblique muscle is solely the function of CN