Anatomy Atlas

Trigeminal nerve (CN V)

Nervus trigeminus
Also: CN V · Cranial nerve V · Ophthalmic nerve · Maxillary nerve · Mandibular nerve · V1 · V2 · V3 · Trigeminal neuralgia
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Largest cranial nerve — sensation from the face, scalp, eye, nose and mouth in three divisions, plus motor supply to the muscles of mastication. Trigeminal neuralgia and shingles of V1 are the classic problems.

Core anatomy

Origin

Leaves the lateral pons as a large sensory root and a small motor root. Nuclei: principal sensory (pons — touch), spinal nucleus (down into the cervical cord — pain and temperature), mesencephalic (proprioception, jaw jerk) and motor nuclei. The sensory cell bodies form the trigeminal (semilunar) ganglion in Meckel cave on the petrous apex.

Course

The ganglion gives three divisions: V1 ophthalmic — lateral wall of the cavernous sinus → superior orbital fissure; V2 maxillary — lateral wall of the cavernous sinus → foramen rotundum → pterygopalatine fossa; V3 mandibular (with the whole motor root) → foramen ovale → infratemporal fossa. Mnemonic "Standing Room Only" (SOF, rotundum, ovale).

Branches
  • V1 ophthalmic (sensory): frontal (supraorbital, supratrochlear), lacrimal, nasociliary (cornea, tip of the nose) — forehead, upper eyelid, cornea, dorsum of nose
  • V2 maxillary (sensory): infraorbital, zygomatic, superior alveolar, palatine and nasal branches — cheek, lower eyelid, upper lip, upper teeth, palate, nasal cavity
  • V3 mandibular (sensory + motor): auriculotemporal, buccal, lingual (anterior 2/3 of tongue), inferior alveolar (lower teeth, chin via the mental nerve) and motor branches
Motor

V3 only: Muscles of mastication (masseter, temporalis, medial and lateral pterygoids), mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini.

Sensory

Face and anterior scalp to the vertex, cornea and conjunctiva, nasal and oral cavities, teeth, anterior two-thirds of the tongue (general sensation), most of the supratentorial dura. The angle of the jaw is supplied by C2–C3 (great auricular nerve), not CN V.

Relations

V1 and V2 run in the lateral wall of the cavernous sinus with CN III and IV (see dural venous sinuses). Parasympathetic fibers from CN VII and IX "hitchhike" on V branches to the lacrimal, nasal, palatine and parotid glands.

Muscles innervated

Other structures innervated

Found in

Mentioned in

Generated automatically from links in other entries.

Foramina of the cranial base (internal view)The floor of the cranial cavity seen from above, anterior at the top, divided into anterior, middle and posterior cranial fossae. Anterior fossa: the cribriform plate transmits the olfactory nerve fibers. Middle fossa: the optic canal transmits the optic nerve and ophthalmic artery; the superior orbital fissure transmits cranial nerves III, IV, the ophthalmic division of V and VI with the superior ophthalmic vein; the foramen rotundum transmits the maxillary nerve; the foramen ovale the mandibular nerve and lesser petrosal nerve; the foramen spinosum the middle meningeal artery. The foramen lacerum is filled with cartilage, and the internal carotid artery, emerging from the carotid canal in the petrous temporal bone, crosses above it. The sella turcica holds the pituitary gland. Posterior fossa: the internal acoustic meatus transmits the facial and vestibulocochlear nerves and labyrinthine artery; the jugular foramen transmits cranial nerves IX, X and XI and the internal jugular vein; the hypoglossal canal transmits cranial nerve XII; the foramen magnum transmits the medulla, the vertebral arteries and the spinal roots of the accessory nerve.Anterior fossaMiddle fossaPosterior fossaCribriform plateCN I (olfactory fibers)Optic canalCN II · ophthalmic arterySuperior orbital fissureCN III, IV, V1, VI · superior ophthalmic v.Foramen rotundumV2 (maxillary)Foramen ovaleV3 (mandibular) · lesser petrosal n.Foramen spinosumMiddle meningeal arteryForamen lacerumCartilage-filled · ICA crosses above itCarotid canal (dashed)Internal carotid a. · sympathetic plexusSella turcicaPituitary glandInternal acoustic meatusCN VII, VIII · labyrinthine arteryJugular foramenCN IX, X, XI · internal jugular veinHypoglossal canalCN XIIForamen magnumMedulla · vertebral aa. · spinal roots of CN XICranial base from above · anterior ↑Not to scale"Standing Room Only": V1 → Superior orbitalfissure, V2 → Rotundum, V3 → Ovale

Swipe sideways to see the whole diagram →

Foramina of the cranial base. Internal view from above, anterior at the top. Each foramen is drawn on both sides and labelled on one. The carotid canal runs inside the petrous bone (dashed) and opens at its apex, where the internal carotid artery crosses above the cartilage-filled foramen lacerum.
Original schematic, created for this atlas.
Lateral dissection showing the trigeminal (semilunar) ganglion with the maxillary and mandibular divisions and their branches, including the lingual, inferior alveolar and auriculotemporal nerves
The trigeminal ganglion with the maxillary and mandibular divisions.
Henry Vandyke Carter, Gray's Anatomy of the Human Body, 20th ed. (1918), Fig. 778. Source · Public domain (Public domain in the US: published before January 1, 1931 (per Wikimedia Commons))
The right orbit opened from above showing the trochlear nerve to the superior oblique, the ophthalmic nerve branches and the trigeminal (semilunar) ganglion
The ophthalmic division and trigeminal ganglion, seen from above.
Henry Vandyke Carter, Gray's Anatomy of the Human Body, 20th ed. (1918), Fig. 776. Source · Public domain (Public domain in the US: published before January 1, 1931 (per Wikimedia Commons))

Clinical correlations

Trigeminal neuralgia PANCE

Mechanism / lesion

Usually vascular compression of the root near the pons (superior cerebellar artery); in a young patient or with bilateral symptoms, think multiple sclerosis.

Classic presentation

Brief (seconds), electric, stabbing unilateral facial pain, usually V2 or V3, triggered by chewing, talking, brushing teeth, touching the face or wind; normal neurologic exam. Carbamazepine (or oxcarbazepine) is first-line; microvascular decompression or ablation if refractory. MRI to exclude secondary causes.

Herpes zoster ophthalmicus PANCE

Mechanism / lesion

Reactivation of varicella-zoster virus in the trigeminal ganglion, V1 distribution.

Classic presentation

Painful vesicular rash on the forehead and upper eyelid; Hutchinson sign (vesicles on the tip of the nose — nasociliary branch) predicts eye involvement (keratitis, uveitis). Oral antivirals within 72 hours and urgent ophthalmology.

Motor (V3) lesion

Mechanism / lesion

Tumors at the skull base or foramen ovale, trauma.

Classic presentation

Weak jaw clench and masseter/temporalis wasting; the jaw deviates toward the weak side on opening (unopposed contralateral lateral pterygoid).

High-yield PANCE pearls

  • Lightning-like facial pain triggered by chewing/touch → trigeminal neuralgia → carbamazepine.
  • Trigeminal neuralgia in a young adult → consider MS.
  • Zoster with vesicles on the nose tip (Hutchinson sign) → eye involvement → ophthalmology.
  • Corneal reflex: afferent V1, efferent VII.
  • Jaw deviates toward a V3 lesion.
  • SOF (V1), rotundum (V2), ovale (V3) — "Standing Room Only".

Imaging anatomy

CT

CT of the skull base foramina for tumors or fractures.

MRI

MRI brain with thin-section imaging of the trigeminal root (e.g. FIESTA/CISS) to show vascular compression or exclude tumor or MS plaques.

Physical exam

Surface landmarks

Supraorbital (V1), infraorbital (V2) and mental (V3) foramina lie on a vertical line through the pupil.

Palpation

Palpate masseter and temporalis while the patient clenches the teeth.

Strength / function testing

Light touch and pinprick (± temperature) in each of the three divisions on both sides (forehead, cheek, jaw — not the angle of the jaw). Motor: clench teeth (palpate masseter/temporalis), open the jaw against resistance (deviation). Jaw jerk (brisk in upper motor neuron lesions above the pons).

Corneal reflex

Technique

Touch the cornea (not the conjunctiva) from the side with a wisp of cotton while the patient looks away.

Positive test

Absent blink in both eyes when one cornea is touched.

Significance

Afferent V1 (nasociliary), efferent CN VII (orbicularis oculi). Loss with preserved blink on stimulating the other eye → V1 lesion (e.g. acoustic neuroma compressing V).

Self-quiz

Q1.

A 62-year-old woman has attacks of stabbing pain in the right cheek lasting a few seconds, set off by brushing her teeth. Neurologic exam is normal. What is the first-line treatment?

Show answer

B

Brief, triggered, electric pain in V2 with a normal exam is trigeminal neuralgia; carbamazepine is first-line. Obtain MRI to exclude a secondary cause.

Q2.

The motor fibers of the trigeminal nerve exit the skull through which foramen?

Show answer

C

All motor fibers travel with V3 (mandibular), which leaves through the foramen ovale. The foramen spinosum transmits the middle meningeal artery.

Q3.

A patient has a vesicular rash over the left forehead and upper eyelid, with vesicles on the tip of the nose. What does the nasal involvement indicate?

Show answer

B

Hutchinson sign — the nasociliary branch of V1 supplies both the nose tip and the eye, so nasal vesicles predict ocular zoster. Urgent ophthalmology and antivirals.

Q4.

Which nerve supplies the skin over the angle of the jaw?

Show answer

B

The angle of the jaw is supplied by the great auricular nerve (C2–C3), not CN V, which helps tell trigeminal from cervical sensory loss.

Q5.

A 28-year-old develops trigeminal neuralgia. Which underlying condition should be considered?

Show answer

E

Trigeminal neuralgia is usually from vascular compression in older adults. In a young patient or with bilateral symptoms, consider multiple sclerosis and obtain MRI.

Flashcards

See also