Editing Trigeminal nerve (section)

== Structure ==

=== Origin ===
From the trigeminal ganglion, a single, large sensory root  enters the [[brainstem]] at the level of the [[pons]]. Immediately adjacent to the sensory root, a smaller motor root emerges from the pons<ref name="pmid29354310">{{cite journal |vauthors=Kontzialis M, Kocak M |date=2017 |title=Imaging evaluation of trigeminal neuralgia |journal=Journal of Istanbul University Faculty of Dentistry |volume=51 |issue=3 Suppl 1 |pages=S62–S68 |doi=10.17096/jiufd.27242 |pmc=5750829 |pmid=29354310}}</ref> slightly rostrally and medially to the sensory root.'''<ref name=":022">{{Cite book |last=Sinnatamby |first=Chummy S. |title=Last's Anatomy |publisher= Elsevier Australia|year=2011 |isbn=978-0-7295-3752-0 |edition=12th |pages=478}}</ref>'''

Motor fibers pass through the trigeminal ganglion without synapsing on their way to peripheral muscles, their cell bodies being located in the nucleus of the fifth nerve, deep within the pons.

=== Trigeminal ganglion ===
The three major branches of the trigeminal nerve—the [[ophthalmic nerve]] (V<sub>1</sub>), the [[maxillary nerve]] (V<sub>2</sub>) and the [[mandibular nerve]] (V<sub>3</sub>)—converge on the [[trigeminal ganglion]] (also called the semilunar ganglion or gasserian ganglion), located within [[Meckel's cave]] and containing the cell bodies of incoming sensory-nerve fibers. The trigeminal ganglion is analogous to the [[dorsal root]] ganglia of the spinal cord, which contain the cell bodies of incoming sensory fibers from the rest of the body.[[File:Gray784.png|thumb|alt=Drawing of the head, with areas served by specific nerves color-coded|[[Dermatome (anatomy)|Dermatome]] distribution of the trigeminal nerve]]

===Sensory branches===
[[File:Trig innervation.svg|thumb|left|alt=Profile of the head, with the three sub-nerves color-coded|Dermatome distribution of the trigeminal nerve]]
The ophthalmic, maxillary and mandibular branches leave the skull through three separate [[Foramina of the skull|foramina]]: the [[superior orbital fissure]], the [[foramen rotundum]] and the [[foramen ovale (skull)|foramen ovale]], respectively. The ophthalmic nerve (V<sub>1</sub>) carries sensory information from the scalp and forehead, the upper eyelid, the conjunctiva and cornea of the eye, the nose (including the tip of the nose, except alae nasi), the nasal mucosa, the frontal sinuses and parts of the [[meninges]] (the [[Dura mater|dura]] and blood vessels). The maxillary nerve (V<sub>2</sub>) carries sensory information from the lower eyelid and cheek, the [[nares]] and upper lip, the upper teeth and gums, the nasal mucosa, the palate and roof of the pharynx, the maxillary, ethmoid and sphenoid sinuses and parts of the meninges. The mandibular nerve (V<sub>3</sub>) carries sensory information from the lower lip, the lower teeth and gums, the chin and jaw (except the angle of the jaw, which is supplied by C2-C3), parts of the external ear and parts of the meninges. The mandibular nerve carries touch-position and pain-temperature sensations from the mouth. Although it does not carry taste sensation (the [[chorda tympani]] is responsible for taste), one of its branches—the [[lingual nerve]]—carries sensation from the tongue.

The peripheral processes of mesencephalic nucleus of V neurons run in the motor root of the trigeminal nerve and terminate in the muscle spindles in the muscles of mastication. They are proprioceptive fibers, conveying information regarding the location of the masticatory muscles. The central processes of mesencephalic V neurons synapse in the motor nucleus V.

=== Dermatomes ===
The areas of cutaneous distribution ([[Dermatome (anatomy)|dermatome]]s) of the three sensory branches of the trigeminal nerve have sharp borders with relatively little overlap (unlike dermatomes in the rest of the body, which have considerable overlap). The injection of a [[local anesthetic]], such as [[lidocaine]], results in the complete loss of sensation from well-defined areas of the face and mouth. For example, teeth on one side of the jaw can be numbed by injecting the mandibular nerve. Occasionally, injury or disease processes may affect two (or all three) branches of the trigeminal nerve; in these cases, the involved branches may be termed:
* '''V1/V2 distribution''' – Referring to the ophthalmic and maxillary branches
* '''V2/V3 distribution''' – Referring to the maxillary and mandibular branches
* '''V1-V3 distribution''' – Referring to all three branches

Nerves on the left side of the jaw slightly outnumber the nerves on the right side of the jaw.