Optic Nerve: Definition & Function

Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

What is the optic nerve? It's the nerve responsible for getting information from your eye to your brain! Keep reading to find out how this nerve functions and then take the quiz to see how much you learned.

Let's See What the Optic Nerve Is!

Optic nerves transmit sensations from the eyes to the brain, so if you can see, you have optic nerves hard at work! When light is refracted in your eye, the retina develops an image, and this image is transported via a series of impulses from the retina by the optic nerves into the brain, which interprets the impulses as an image you comprehend! So you can think of optic nerves as little pipelines of picture information heading into your brain.

The arrow in this diagram shows the optic nerve connecting the eye to the brain.
optic nerve

A really cool fact: the optic nerve is found in the back of your eye, and the head of the optic nerve is visible using an ophthalmoscope, making it the ONLY part of your brain viewed from outside your body (technically it's an extension of your brain, but that's still really cool to think about). Our bodies have 12 cranial nerves (nerves transmitting information around the head), and the optic nerve is the second, making it also known as cranial nerve II or the second cranial nerve.

How Does the Optic Nerve Function?

The optic nerve may be found in your eye, but it is part of the central nervous system. The optic nerve takes visual information gathered from your eye and transmits it using a series of electrical impulses to the parts of your brain that act as vision centers, allowing you to make sense of what you are seeing. Each optic nerve is a bundle of more than one million nerve cell fibers (specifically, Ganglionic cells) that work together to help you see. Another fun fact: the place where the optic nerve leaves your eye doesn't have any photoreceptors, so this spot is actually a blind spot!

A diagram of the eye; you can see the optic nerve is opposite the visible part of the eye (the pupil, iris, lens, and cornea)
optic nerve eyeball diagram

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