Skip to main content
Neuroscience · Structure

Cranial Nerves Diagram

All twelve cranial nerves seen from under the brain, in order from front to back, with each one's function, skull opening and bedside test.

The brain from below, front at the top, simplified and not to scale: the frontal lobes with the olfactory bulbs, the optic nerves meeting at the chiasm, the temporal lobes at the sides, then the midbrain, pons and medulla in front of the cerebellum. The twelve nerves leave in numbered order from front to back; both sides' roots are drawn, each pair labelled once. Press any nerve for its job, skull opening and test.

Also called 12 cranial nerves, Cranial nerves chart, Cranial nerve mnemonic or Cranial nerves and their functions.

The underside of the human brain, front at the top, with the twelve cranial nerves labelled on one side. On the frontal lobes lie the olfactory bulbs and tracts (I). The two optic nerves (II) meet at the optic chiasm, with the pituitary stalk behind it and the optic tracts running back to the temporal lobes at the sides. The oculomotor nerves (III) leave the midbrain between its two cerebral peduncles and the trochlear nerves (IV) appear round their sides. The trigeminal nerves (V) leave the sides of the pons; along its lower border leave the abducens (VI) near the midline and the facial (VII) and vestibulocochlear (VIII) nerves at the side. From the medulla, with its pyramids and olives, leave the glossopharyngeal (IX), vagus (X) and accessory (XI) nerves behind the olive and the hypoglossal (XII) in front of it; the accessory nerve's spinal root climbs from the spinal cord. The cerebellum lies behind the brainstem.Frontal lobeI Olfactorysensory: smellII Opticsensory: visionIII Oculomotormotor: eye, lid, pupilIV Trochlearmotor: superior obliqueV Trigeminalboth: face, chewingVI Abducensmotor: lateral rectusMedulla (olive)XII Hypoglossalmotor: tongueCerebellumSpinal cordOptic chiasmPituitary stalkMidbrain (cerebral peduncle)Temporal lobePonsVII Facialboth: face muscles, tasteVIII Vestibulocochlearsensory: hearing, balanceIX Glossopharyngealboth: throat, tasteX Vagusboth: throat, heart, gutXI Accessorymotor: shoulder, neck
View

Press any part of the diagram, or pick one here, to see what it is and what it does.

Download the diagramChecked against its sources on 5 November 2026.

A tour

A tour of the cranial nerves

  1. 01Twelve pairs, numbered from front to back

    Twelve pairs of nerves leave the brain and brainstem directly, unlike the spinal nerves, which leave the cord. They are numbered I to XII in the order they attach from front to back, so the number tells you where to look: I and II on the forebrain, III and IV on the midbrain, V to VIII on the pons, IX to XII on the medulla. Three are purely sensory (I, II, VIII), five purely motor (III, IV, VI, XI, XII) and four carry both (V, VII, IX, X).

  2. 02I and II: the forebrain

    The first two are not ordinary peripheral nerves. The olfactory nerve is the fine filaments that rise from the nose through the cribriform plate into the olfactory bulb; the bulb and tract, part of the brain itself, carry smell back to the temporal lobe. The optic nerve is an outgrowth of the brain, myelinated by oligodendrocytes, not Schwann cells; it brings vision from the eye through the optic canal to the chiasm, where the fibres from the nasal half of each retina cross.

  3. 03III and IV: the midbrain

    The oculomotor nerve leaves the interpeduncular fossa between the two cerebral peduncles and runs forward to the orbit. The trochlear nerve is the odd one out: it leaves the back of the midbrain, below the inferior colliculus, having crossed to the other side, then winds round the peduncle to appear at its side. Both pass through the cavernous sinus and the superior orbital fissure.

  4. 04V to VIII: the pons

    The trigeminal nerve, the largest, leaves the side of the pons. Along the lower border of the pons, where it meets the medulla, three more leave: the abducens near the midline, and the facial and vestibulocochlear nerves at the side, in the angle between pons and cerebellum, from which they travel together into the internal acoustic meatus.

  5. 05IX to XII: the medulla

    Four nerves leave the medulla. The glossopharyngeal, vagus and accessory nerves leave in a row behind the olive and pass together through the jugular foramen; the hypoglossal nerve leaves in front of the olive, between it and the pyramid, and has a canal of its own. The accessory nerve's spinal root comes up from the cervical cord through the foramen magnum to join them.

  6. 06Sensory, motor or both: Some Say Marry Money

    Some Say Marry Money But My Brother Says Big Brains Matter More gives the type of each nerve in order: S for sensory, M for motor, B for both. So I, II and VIII are sensory; III, IV, VI, XI and XII motor; V, VII, IX and X mixed. Four nerves also carry parasympathetic fibres to glands, the eye and the organs: III, VII, IX and X.

  7. 07The names: Oh Oh Oh To Touch And Feel

    Oh Oh Oh To Touch And Feel Very Good Velvet, Such Heaven: Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Spinal accessory, Hypoglossal. Say it with the picture in front of you, matching each word to a root from front to back, and the order will stay with you.

  8. 08III, IV and VI move the eye

    Three nerves move the eye. The oculomotor supplies four of its six muscles and the lid and constricts the pupil; the trochlear supplies only the superior oblique; the abducens only the lateral rectus. All three enter the orbit through the superior orbital fissure and are tested together with a finger moved in an H. A third nerve palsy leaves the eye down and out with a drooping lid; a sixth stops it turning outwards; a fourth gives vertical double vision, worst looking down.

  9. 09I, II and VIII: the special senses

    Smell, sight, and hearing with balance each have a nerve of their own, and all three are purely sensory. They are tested in turn: a familiar scent in each nostril with the eyes closed; the acuity chart, the visual fields by confrontation, the pupils' response to light and the back of the eye; a whisper or rubbed fingers at each ear, then tuning-fork tests to tell conductive from sensorineural hearing loss.

  10. 10The vagus, the wanderer

    The vagus is the longest cranial nerve and the one that leaves the head and neck: from the jugular foramen it runs down beside the carotid artery into the chest and abdomen. It moves the palate, pharynx and larynx, slows the heart, constricts the airways and drives the gut as far as the splenic flexure, and most of its fibres are sensory, reporting back from these organs. Its recurrent laryngeal branch can be injured in thyroid surgery, leaving the voice hoarse.

  11. 11Testing them at the bedside, in order

    Clinicians test the nerves in order. I: a scent in each nostril. II: acuity, fields, pupils, fundus. III, IV, VI: follow a finger in an H. V: light touch on forehead, cheek and jaw, clench the teeth, corneal reflex. VII: raise the eyebrows, shut the eyes tight, show the teeth, puff the cheeks. VIII: whisper, tuning forks. IX, X: say ah, watch the palate and uvula, gag reflex, voice. XI: shrug and turn the head against resistance. XII: stick out the tongue.

Parts

What each part of the cranial nerves does

I Olfactory nerve
Sensory: smell. Fine fibres from the nose pass through the holes of the cribriform plate of the ethmoid bone and end in the olfactory bulb on the under-surface of the frontal lobe; the tract carries the signal back towards the temporal lobe. A head injury can shear these fibres at the plate and abolish smell (anosmia).
II Optic nerve
Sensory: vision. The axons of 1.2 million retinal ganglion cells form each nerve, which enters the skull by the optic canal to meet its fellow at the chiasm. An outgrowth of the brain, myelinated by oligodendrocytes, not Schwann cells. Optic neuritis, often in multiple sclerosis, blurs one eye and hurts on moving it.
III Oculomotor nerve
Motor. From the interpeduncular fossa it runs through the cavernous sinus and superior orbital fissure to four of the six eye muscles and the lid's levator, plus parasympathetic fibres to the pupil. A palsy leaves the eye down and out with a drooping lid; a fixed, dilated pupil suggests an aneurysm pressing on it.
IV Trochlear nerve
Motor to the superior oblique only. The thinnest cranial nerve, the only one to leave the back of the brainstem; it crosses to the other side, winds round the midbrain and enters the orbit. A palsy gives vertical double vision, worst looking down and in, and a head tilt away from the weak eye.
V Trigeminal nerve
Both, and the largest cranial nerve. It leaves the side of the pons with a large sensory and a small motor root and divides at its ganglion into the ophthalmic, maxillary and mandibular nerves. It feels the face, eye, nose, mouth and teeth; V3 moves the chewing muscles. Trigeminal neuralgia is its electric-shock pain.
VI Abducens nerve
Motor to the lateral rectus, which turns the eye outwards. It leaves where pons meets medulla, near the midline, runs far forward to the cavernous sinus and orbit. A palsy stops the eye abducting, with horizontal double vision worst looking that way; raised pressure in the skull can damage it.
VII Facial nerve
Both. From the pontomedullary junction it enters the internal acoustic meatus and leaves the skull at the stylomastoid foramen for the muscles of facial expression. It also carries taste from the front two-thirds of the tongue and drives the tear and salivary glands. Bell's palsy is its sudden one-sided weakness.
VIII Vestibulocochlear nerve
Sensory: hearing and balance. Its cochlear and vestibular parts run with the facial nerve through the internal acoustic meatus. A vestibular schwannoma (acoustic neuroma), a benign tumour of its Schwann cells, grows here, causing one-sided hearing loss, tinnitus and unsteadiness; about one person in 100,000 a year.
IX Glossopharyngeal nerve
Both. It leaves the side of the medulla and the skull by the jugular foramen. It carries taste and sensation from the back third of the tongue and pharynx, senses blood pressure at the carotid sinus, drives the parotid gland and moves the stylopharyngeus. Sensory limb of the gag reflex; the vagus is the motor limb.
X Vagus nerve
Both; the longest cranial nerve. It leaves the medulla as rootlets behind the olive, passes the jugular foramen and wanders down to the abdomen. It moves palate, pharynx and larynx and supplies the heart, lungs and gut; most of its fibres are sensory. A palsy: hoarse voice, uvula pulled to the healthy side.
XI Accessory nerve
Motor to the sternocleidomastoid and trapezius. Most of it arises from the upper cervical cord: its spinal roots climb through the foramen magnum into the skull and leave again, with IX and X, through the jugular foramen. Damage weakens the shrug and turning the head to the other side, and the shoulder droops.
XII Hypoglossal nerve
Motor to the tongue muscles. Its rootlets leave the medulla between the pyramid and the olive and gather into the hypoglossal canal. Asked to stick the tongue out, a patient with a damaged nerve sees it deviate towards the weak side, pushed across by the healthy genioglossus; in time that side wastes and twitches.
Frontal lobes
The under-surface of the frontal lobes, with the longitudinal fissure between them. The olfactory bulb and tract lie here, between the gyrus rectus beside the midline and the orbital gyri, in the anterior cranial fossa.
Temporal lobes
The temporal lobes bulge out at the sides, separated from the frontal lobe in front by the stem of the lateral sulcus. Smell is perceived on their inner surface, in the piriform cortex and amygdala, where the olfactory tract ends.
Optic chiasm
Where the two optic nerves meet. Fibres from the nasal half of each retina, which see the outer half of the visual field, cross here to the other side; those from the temporal half stay on their own side. A pituitary tumour pressing on the chiasm cuts off both outer fields: bitemporal hemianopia.
Pituitary stalk
The cut stalk, or infundibulum, by which the pituitary gland hangs from the base of the brain, just behind the optic chiasm. This closeness is why a pituitary tumour growing upwards presses on the chiasm and narrows the visual fields.
Midbrain
The top of the brainstem, mostly hidden between the temporal lobes. From below, its two cerebral peduncles run up from the pons into the hemispheres with the interpeduncular fossa between them. The oculomotor nerve (III) leaves from the fossa; the trochlear (IV) leaves the back of the midbrain and winds round its side.
Pons
The bulging middle part of the brainstem. The trigeminal nerve (V) leaves its side, and the abducens (VI), facial (VII) and vestibulocochlear (VIII) nerves leave along its lower border, where it meets the medulla.
Medulla oblongata
The lowest part of the brainstem, which continues down as the spinal cord. Beside the midline run the pyramids, and lateral to them the oval olives. The hypoglossal nerve (XII) leaves between pyramid and olive; the glossopharyngeal (IX), vagus (X) and accessory (XI) nerves leave in a row behind the olive.
Cerebellum
Behind the brainstem, its two hemispheres show below the back of the cerebrum. In the angle between it and the pons, the cerebellopontine angle, the facial and vestibulocochlear nerves leave for the internal acoustic meatus, and a vestibular schwannoma grows here and in that canal.
Spinal cord
The medulla becomes the spinal cord at the foramen magnum. The spinal root of the accessory nerve (XI) arises from the cord's upper cervical segments and climbs up beside it through the foramen magnum into the skull.

As a table

The cranial nerves as a table

The twelve cranial nerves in order, with the type of fibres each carries, its main functions, the opening through which it leaves the skull and a quick bedside test.

  • I Olfactory

    Type
    Sensory
    Main functions
    Smell
    Leaves the skull through
    Cribriform plate of the ethmoid bone
    Quick bedside test
    Identify a familiar scent in each nostril, eyes closed

  • II Optic

    Type
    Sensory
    Main functions
    Vision; sensory limb of the pupillary light reflex
    Leaves the skull through
    Optic canal
    Quick bedside test
    Acuity chart, visual fields by confrontation, pupil reactions, fundoscopy

  • III Oculomotor

    Type
    Motor (with parasympathetic fibres)
    Main functions
    Superior, inferior and medial rectus, inferior oblique and levator palpebrae; constricts the pupil and focuses the lens
    Leaves the skull through
    Superior orbital fissure
    Quick bedside test
    Follow a finger in an H; look for a drooping lid, a dilated pupil, an eye turned down and out

  • IV Trochlear

    Type
    Motor
    Main functions
    Superior oblique: turns the eye down and rotates it inwards (intorsion)
    Leaves the skull through
    Superior orbital fissure
    Quick bedside test
    Look down and in; vertical double vision and a head tilt away from the weak eye

  • V Trigeminal

    Type
    Both
    Main functions
    Sensation from the face, scalp, eye, nose, mouth and teeth; the chewing muscles (V3)
    Leaves the skull through
    Superior orbital fissure (V1), foramen rotundum (V2), foramen ovale (V3)
    Quick bedside test
    Light touch in the three divisions, the corneal reflex, clench the teeth and feel the masseters

  • VI Abducens

    Type
    Motor
    Main functions
    Lateral rectus: turns the eye outwards
    Leaves the skull through
    Superior orbital fissure
    Quick bedside test
    Look to each side; the weak eye fails to turn outwards

  • VII Facial

    Type
    Both
    Main functions
    Muscles of facial expression and the stapedius; taste from the front two-thirds of the tongue; lacrimal and salivary glands (not the parotid)
    Leaves the skull through
    Internal acoustic meatus, then the stylomastoid foramen
    Quick bedside test
    Raise the eyebrows, shut the eyes tight, show the teeth, puff out the cheeks

  • VIII Vestibulocochlear

    Type
    Sensory
    Main functions
    Hearing (cochlear part) and balance (vestibular part)
    Leaves the skull through
    Internal acoustic meatus
    Quick bedside test
    Whispered words or rubbed fingers at each ear; Rinne and Weber tuning-fork tests

  • IX Glossopharyngeal

    Type
    Both
    Main functions
    Taste and sensation from the back third of the tongue and the pharynx; carotid sinus and body; parotid gland; stylopharyngeus
    Leaves the skull through
    Jugular foramen
    Quick bedside test
    Gag reflex (its sensory limb) and swallowing, tested together with X

  • X Vagus

    Type
    Both
    Main functions
    Palate, pharynx and larynx; parasympathetic supply to the heart, lungs and gut as far as the splenic flexure; sensation from the organs
    Leaves the skull through
    Jugular foramen
    Quick bedside test
    Say ah: the palate rises evenly and the uvula stays central; voice, cough, gag reflex (its motor limb)

  • XI Accessory

    Type
    Motor
    Main functions
    Sternocleidomastoid and trapezius
    Leaves the skull through
    Jugular foramen (its spinal root enters through the foramen magnum)
    Quick bedside test
    Shrug the shoulders and turn the head against resistance

  • XII Hypoglossal

    Type
    Motor
    Main functions
    Muscles of the tongue
    Leaves the skull through
    Hypoglossal canal
    Quick bedside test
    Stick out the tongue: it deviates towards the weak side; push it into each cheek

The numbers follow the order in which the nerves attach to the brain from front to back. The bedside tests are those of the StatPearls chapter Cranial Nerve Testing; IX and X are tested together because they share the palate, pharynx and gag reflex.

Dictionary

The terms to know

Practise it

The quizzes and cards that fit

Next to it

More diagrams

Sources

Where the facts come from

Drawn and written by biofideX from these sources.

Cookie Notice

We use cookies

biofideX uses cookies and similar technologies to keep you signed in, remember your preferences, and (with your consent) measure how the platform is used. Change your choices any time from the Cookie Policy.