Core idea
One nerve, three major routes
The trigeminal nerve is the fifth cranial nerve. It is a mixed nerve: its large sensory component gathers information from the face, mouth, nasal spaces, and parts of the eye, while its motor component helps activate the muscles of mastication.
On this page
The three divisions
The nerve emerges from the pons with a large sensory root and a smaller motor root. Its sensory root reaches the trigeminal ganglion, from which three divisions continue into the face and head.
Ophthalmic division · V1
V1 is sensory. It carries information from the forehead, upper eyelid, cornea, conjunctiva, and parts of the nose and nasal cavity. It enters the orbit through the superior orbital fissure.
Maxillary division · V2
V2 is sensory. It serves areas including the lower eyelid, cheek, upper lip, palate, nasal spaces, and maxillary sinus. It passes through the foramen rotundum.
Mandibular division · V3
V3 is mixed. It carries sensation from the lower face and mouth and supplies the muscles of mastication and several smaller muscles.
Nuclei and pathways
The trigeminal system uses several connected nuclei in the brainstem. The main sensory nucleus processes touch and pressure. The spinal nucleus is associated especially with pain and temperature. The mesencephalic nucleus carries proprioceptive information, including signals linked to chewing. The motor nucleus sends commands to muscles supplied by V3.
After processing in the brainstem, ascending fibres travel towards the thalamus and then the somatosensory cortex. This route allows the brain to identify where a sensation began and what kind of sensation it is.
What does the trigeminal nerve do?
Sensation: the nerve carries general sensory information such as touch, pressure, pain, and temperature from much of the face. Its branches also gather information from oral and nasal mucous membranes and from the front part of the tongue, without carrying taste itself.
Movement: the motor component of V3 activates the masseter, temporalis, and pterygoid muscles. Together, these muscles move the mandible for biting, chewing, and other jaw movements. V3 also supplies a number of smaller muscles in the region.
Protective and movement reflexes
The jaw-jerk reflex uses sensory information from the muscles involved in chewing and a motor response that briefly contracts those muscles. Clinicians may use it as one part of a neurological examination.
The corneal reflex protects the eye. Sensory input from the cornea travels through the ophthalmic division; the response is carried through the facial nerve to muscles that close the eyelids. A blink is therefore a coordinated response involving more than one cranial nerve.
Clinical context
Problems affecting the trigeminal nerve can alter facial sensation, jaw movement, or both. The pattern depends on which division or pathway is involved. Trigeminal neuralgia is associated with brief, severe episodes of facial pain, often in areas supplied by V2 or V3. Other conditions may cause numbness, weakness during chewing, or changes in reflexes.
Assessment and treatment depend on the person’s symptoms and the underlying cause. A qualified clinician may examine sensation, jaw strength, and reflexes and may arrange further tests when appropriate. This educational page cannot diagnose pain or replace medical care.
Summary
The trigeminal nerve is CN V and has three divisions: ophthalmic V1, maxillary V2, and mandibular V3. V1 and V2 are sensory; V3 combines sensory fibres with motor fibres for the muscles of mastication. Brainstem nuclei and ascending pathways help turn signals from the face into recognised sensations, while trigeminal pathways also contribute to the jaw-jerk and corneal reflexes.
For a wider view, compare this page with the cranial nerves guide and related pages on the facial nerve, cerebral cortex, and central nervous system.