The trigeminal nucleus is located in the brainstem and emanates from the semilunar ganglion of the trigeminal nerve in three nerves, the ophthalmic nerve, the maxillary nerve, and the mandibular nerve.
The trigeminal nerve is a mixed nerve, containing both general somatic sensory and specific visceral motor nerve fibers. Its sensory fiber level 1 neurons are located in the semilunar ganglion of the trigeminal nerve, which is located in the rocky tip of the temporal bone at the trigeminal nerve indentation, and its peripheral eminence divides into the ophthalmic meridian, the maxillary nerve, and the mandibular nerve branches.
The first branch is the ophthalmic nerve, which receives sensations from the anterior scalp, forehead, upper eyelid and skin of the anterior half of the nose, as well as the mucous membranes of the upper part of the nasal cavity, the frontal sinus, the cornea and the conjunctiva, and enters the cranium through the supraorbital fissure.
The 2nd branch is the maxillary nerve, which is distributed in the skin between the eye and the cleft of the mouth, the upper lip, the maxillary teeth and gingiva, the hard and soft palate, the anterior part of the tonsillar fossa, the mucous membranes of the nasal cavity, the maxillary sinus and the nasopharynx, etc., and enters the cranium through the round foramen.
The third branch is the mandibular nerve, parallel to the motor branch of the trigeminal nerve, sensory fibers are distributed in the ear temporal region and the skin below the cleft of the mouth, the teeth and gums of the mandible, the anterior two-thirds of the tongue and the mucous membrane of the floor of the mouth, and enters the cranium through the foramen ovale.
Trigeminal motor fibers originate from the trigeminal motor nucleus of the cerebral bridge, and send out fibers in the lateral part of the cerebral bridge out of the brain, out of the cranium through the foramen ovale, and travel in the mandibular nerve, innervating the masticatory muscles (temporal, biting, intrapterygoid, extrapterygoid) and tympanic membrane tensor muscles, and so on.