Which structure carries neural impulses from the eye to the brain?

• A. The light-reflecting layer at the back of the eye
• B. the nerve that carries neural impulses from the eye to the brain
• C. A clear, protective outer layer of the eye
• D. The colored ring that controls pupil size

Answer: (B)

Neural signals from the eye to the brain are carried by the optic nerve, which is formed by the axons of retinal ganglion cells. Light is detected by photoreceptors in the retina and converted into electrical signals that travel through the retinal neurons to the ganglion cells. The axons of these cells bundle together to form the optic nerve, which then transmits the impulses toward the brain for processing. The other eye structures mentioned don’t carry signals to the brain: the back-of-eye layer that reflects light isn’t for transmission, the clear outer layer is the cornea, and the colored ring is the iris that controls pupil size.