Trigeminal nerve: facial sensation and facial harmonization
- Nerve
- Highlighted area
Quick facts
- Definition
- Fifth cranial nerve (V), the main sensory nerve of the face.
- Type
- Mixed: sensory for the face and motor for the muscles of mastication.
- Divisions
- Ophthalmic (V1), maxillary (V2) and mandibular (V3).
- Motor function
- Masseter, temporalis, pterygoids and some muscles of the floor of the mouth, through the mandibular branch.
- Relevance in facial harmonization
- Explains pain, anesthesia and paresthesia after procedures; the facial nerve is the one that controls expression.
The trigeminal nerve is the fifth cranial nerve and the main nerve of facial sensation. It carries the sensations of touch, pain and temperature from the skin, mucous membranes and teeth to the brain, and it also controls the muscles of mastication. It divides into three branches: ophthalmic (V1), maxillary (V2) and mandibular (V3). In facial harmonization, it is the nerve that explains procedural pain, the effect of anesthetic and paresthesia when a branch is irritated.
What are the branches and what does each one supply?
| Division | Leaves the skull through | Skin area | Branches of interest in facial harmonization |
|---|---|---|---|
| Ophthalmic (V1) | Superior orbital fissure | Forehead, anterior scalp, upper eyelid, nasal dorsum and tip | Supraorbital and supratrochlear, external nasal |
| Maxillary (V2) | Foramen rotundum | Lower eyelid, cheek, upper lip, nostril wing, anterior temple | Infraorbital, zygomaticotemporal, zygomaticofacial |
| Mandibular (V3) | Foramen ovale | Lower lip, chin, jaw region, temple and front of the ear | Mental, buccal, auriculotemporal |
A useful exception: the skin over the angle of the mandible is not supplied by the trigeminal but by the great auricular nerve, which comes from the cervical plexus. That is why anesthesia of the trigeminal branches does not cover this area.
Trigeminal or facial: what is the difference?
This is the most common mix-up. The facial nerve (VII) is the motor nerve of expression: it raises the brow, closes the eye and makes the smile. The trigeminal (V) is sensory for the face and motor only for mastication: masseter, temporalis and pterygoids.
| Sign after a procedure | Most likely nerve |
|---|---|
| Numbness, tingling, burning sensation | Trigeminal (sensory branch) |
| Brow that does not rise, crooked smile, lip that does not lower | Facial, or toxin effect in an expression muscle |
| Weaker chewing after toxin in the masseter | Effect on the muscle supplied by the trigeminal (V3) |
Why does it matter in facial harmonization?
- Anesthesia: the blocks used for lips and chin act on trigeminal branches (infraorbital and mental). The overview is in local anesthesia in facial harmonization.
- Paresthesia: compression from volume, or needle trauma near the foramina, can irritate a branch and cause altered sensation.
- Toxin in the masseter: the muscle is supplied by V3, and the expected effect on chewing is part of the conversation. See botulinum toxin in the masseter.
- Medical history: trigeminal neuralgia, herpes zoster on the face and prior surgeries change the assessment and must be in the patient record.
Also called: fifth cranial nerve, trigeminal nerve, nervus trigeminus, cranial nerve V.
Frequently asked questions
What is the difference between the trigeminal nerve and the facial nerve?
The trigeminal is the nerve of facial sensation and also moves the muscles of mastication. The facial nerve controls the muscles of expression. Numbness after a procedure points to the trigeminal; difficulty moving the mouth or brow points to the facial nerve or to a toxin effect.
What are the branches of the trigeminal nerve?
There are three: ophthalmic (V1), which covers the forehead, upper eyelid and nasal dorsum; maxillary (V2), which covers the lower eyelid, cheek, upper lip and nostril wing; and mandibular (V3), which covers the lower lip, chin, part of the jaw and temple, and also moves the muscles of mastication.