Final answer:
The statement that cranial nerve II, or the optic nerve, functions in eyesight is true. The optic nerve carries visual information from the retina to the brain, enabling the sense of sight.
Step-by-step explanation:
The statement Cranial nerve II's function is eyesight is true. The cranial nerve II, also known as the optic nerve, is responsible for transmitting visual information from the retina to the brain. This nerve is purely sensory and is dedicated solely to the function of vision. The optic nerve begins at the back of the eye where the retina converts light stimuli into electrical impulses. These impulses travel along the optic nerve to the visual cortex of the brain, which processes the information, allowing us to see.
When examining the functionality of cranial nerves, tests such as following the tip of a pen with one's eyes are often used to assess the proper functioning of nerves associated with eye movements. However, the optic nerve is not involved in the movement of the eye; that function is served by other cranial nerves like the oculomotor, trochlear, and abducens nerves. These latter nerves coordinate eye muscles to stabilize vision and control eye movements, which is essential for keeping visual stimuli centered on the fovea of the retina for clear vision.