How many nerves innervate the six extraocular muscles?

The correct answer is three because the six extraocular muscles responsible for eye movement are innervated by three cranial nerves. These nerves include the oculomotor nerve (cranial nerve III), which innervates four of the muscles; the trochlear nerve (cranial nerve IV), which innervates the superior oblique muscle; and the abducens nerve (cranial nerve VI), which innervates the lateral rectus muscle.

Understanding the innervation of these muscles is crucial in the study of eye movements and the nervous system, as they work together to control the direction of gaze. Each nerve plays a specific role in coordinating the movements needed for both horizontal and vertical eye motions, which is essential for proper visual function and alignment.