Group

Cranial nerves

Also called Nervi craniales, Cranial nerves I to XII

Twelve pairs of nerves wired straight from the brain to your eyes, face, throat, and gut.

The cranial nerves lit up in a 3D model of the human brain

Most nerves in your body plug into the spinal cord. These 12 pairs are special: they leave the brain directly, through small holes in the skull. They let you smell, see, hear, taste, move your eyes, make faces, chew, swallow, and talk. One of them, the vagus, even reaches all the way down to your heart and gut.

The twelve cranial nerves

Number	Nerve	Type	Main job
I	Olfactory	Sensory	Smell
II	Optic	Sensory	Vision
III	Oculomotor	Motor	Moves most eye muscles, raises the eyelid, narrows the pupil
IV	Trochlear	Motor	Moves the eye down and in (superior oblique muscle)
V	Trigeminal	Both	Feeling in the face; the chewing muscles
VI	Abducens	Motor	Moves the eye outward (lateral rectus muscle)
VII	Facial	Both	Facial expressions; taste on the front of the tongue; tears and saliva
VIII	Vestibulocochlear	Sensory	Hearing and balance
IX	Glossopharyngeal	Both	Taste on the back of the tongue; swallowing; senses blood pressure
X	Vagus	Both	Throat and voice box; slows the heart; runs the gut
XI	Accessory	Motor	Shrugging the shoulders and turning the head
XII	Hypoglossal	Motor	Moves the tongue

Memory tricks

The names, in orderOh Oh Oh To Touch And Feel Very Good Velvet, Such HeavenOlfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Spinal accessory, Hypoglossal

Sensory, motor or bothSome Say Marry Money, But My Brother Says Big Brains Matter MoreS = sensory, M = motor, B = both, in order from I to XII

Where it is

On the underside of the brain. The first two pairs (smell and sight) attach to the front of the brain. The other ten attach to the brainstem, the stalk at the base of the brain, roughly in order from top to bottom.

What it does

Senses of the head

They carry smell, sight, hearing, balance, taste, and touch from your face and head into the brain.

Aiming the eyes

Three of them (III, IV, and VI) work together to point both eyes at exactly the same spot, so you see one clear picture instead of two.

Face, mouth, and throat

They move the muscles you use to smile, chew, swallow, talk, and stick out your tongue.

Body autopilot

Some carry calming "rest and digest" signals that slow the heart, make tears and saliva, and keep food moving through the gut.

Think of them as 12 private phone lines running straight from the head office to the most important rooms in the building, with no switchboard in between.

Inside the cranial nerves

Olfactory nerve & bulb (I)Your smell line: the only sense that skips the thalamus and heads straight to emotion.
Optic nerve (II)The cable from each eye to the brain, and really a piece of brain grown out to the eye.
Oculomotor nerve (III)The main eye mover: it aims your eye, lifts your eyelid, and shrinks your pupil.
Trochlear nerve (IV)The thinnest cranial nerve, running one eye muscle that loops through a tiny pulley.
Trigeminal nerve (V)The face's feeling nerve: touch, pain, and heat from your whole face, plus chewing.
Abducens nerve (VI)Turns each eye outward, so you can glance to the side without moving your head.
Facial nerve (VII)The nerve behind every smile, frown, and wink, and it carries taste from your tongue.
Vestibulocochlear nerve (VIII)Two nerves in one: hearing from the snail-shaped cochlea and balance from the inner ear.
Glossopharyngeal nerve (IX)Tastes the back of your tongue, starts your gag reflex, and checks your blood pressure.
Vagus nerve (X)The "wandering" nerve that runs from your brainstem to your heart, lungs, and gut.
Accessory nerve (XI)Lets you shrug your shoulders and turn your head, and takes a strange U-turn to get there.
Hypoglossal nerve (XII)The tongue's movement nerve, for talking, chewing, swallowing, and sticking it out.

Works with

BrainstemTen of the twelve pairs plug into the brainstem, which holds their control centers.
MidbrainThe two top eye-moving nerves, III and IV, start in the midbrain.
PonsThe face-feeling nerve (V) leaves the pons, and nerves VI, VII, and VIII leave from its lower edge.
Medulla oblongataThe last four nerves, IX to XII, run the throat, voice, neck, and tongue from the medulla.
Spinal cordThe accessory nerve (XI) is unusual: its fibers start partly in the top of the spinal cord.
Frontal lobeThe smell bulbs (nerve I) rest right under the front of the frontal lobes.

When it goes wrong

A quick check-up

A doctor can test all 12 pairs in a few minutes with simple requests like "follow my finger", "smile", "shrug", and "stick out your tongue". Which test fails helps show where a problem is.

Warning signs

Sudden double vision, a drooping face, or slurred speech can mean a stroke or rising pressure inside the skull is affecting these nerves. These need emergency care.

For learning only, not medical advice. If you have a health concern, talk to a doctor.

Surprising facts

A classic memory trick for the names in order: "Ooh, Ooh, Ooh To Touch And Feel Very Good Velvet. Such Heaven!" That stands for Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Spinal accessory, Hypoglossal.
Another trick tells you what each one does, with S for sensory, M for motor (movement), and B for both: "Some Say Marry Money, But My Brother Says Big Brains Matter More."
They are numbered with Roman numerals roughly from front to back, in the order they leave the brain. That is why smell is number I and the tongue nerve is number XII.

By the numbers

12Pairs

3Sensing only: I, II and VIII

5Movement only: III, IV, VI, XI and XII

4Both sensing and movement: V, VII, IX and X

Where the name comes from

Cranial comes from the Greek kranion, meaning "skull". So these are simply the "skull nerves", the ones that begin inside the skull.

Quick quiz

6 questions. Your answers are saved and come back in your daily review.

Which cranial nerve moves the eye outward, toward the ear?
Show the answer
Abducens nerve (VI). The abducens nerve (VI) "abducts" the eye, turning it away from the nose.
A person can't close one eye or smile on that side of the face. Which nerve is affected?
Show the answer
Facial nerve (VII). The facial nerve (VII) moves the muscles of expression; this is what happens in Bell's palsy.
Which nerve carries hearing and balance?
Show the answer
Vestibulocochlear nerve (VIII). The vestibulocochlear nerve (VIII) joins a hearing branch (cochlear) and a balance branch (vestibular).
Which cranial nerve slows the heart and helps run digestion?
Show the answer
Vagus nerve (X). The vagus nerve (X) carries most of the parasympathetic signals to the chest and belly.
Which nerve carries feeling from the face and works the chewing muscles?
Show the answer
Trigeminal nerve (V). The trigeminal nerve (V) has three sensory branches and a motor branch for chewing.
Which nerve moves the tongue?
Show the answer
Hypoglossal nerve (XII). The hypoglossal nerve (XII) runs "under the tongue" to its muscles.

Sources

Neuroanatomy, Cranial Nerve, StatPearls, NCBI Bookshelf
Cranial Nerve Testing, StatPearls, NCBI Bookshelf
Cranial Nerves: Function, Anatomy & Location, Cleveland Clinic

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