Trigeminal nerve (CN V)
The trigeminal nerve (fifth cranial nerve, CN V, latin: nervus trigeminus) is a mixed nerve containing sensory and motor fibers. The trigeminal nerve provides sensory innervation for the mucous membrane of the oral and nasal cavities, the ear, conjunctiva, and the skin of the face. The motor fibers of the trigeminal nerve innervate the muscles of the first branchial arch.
The trigeminal nerve is the largest of the cranial nerves and it develops from the mesoderm of the first branchial arch. The fifth cranial nerve emerges from the brainstem between the pons and the middle cerebral peduncles with two roots: the sensory and the motor root of the trigeminal nerve.
The trigeminal nerve is connected with four nuclei in the central nervous system providing the nerve with fibers of different modalities, and these are:
- trigeminal motor nucleus,
- principal sensory nucleus,
- spinal trigeminal nucleus,
- mesencephalic trigeminal nucleus.
The only somatic motor nucleus of the trigeminal nerve - the trigeminal motor nucleus is located in the pons. The trigeminal nerve has three sensory nuclei: the principal sensory nucleus located in the pons, the spinal trigeminal nucleus - in the medulla oblongata, and the mesencephalic trigeminal nucleus - in the midbrain. The sensory root of the trigeminal nerve has an enlargement - the trigeminal ganglion, which is formed by the cell bodies (perikaryons) of pseudounipolar neurons providing sensory fibers for the trigeminal nerve.
Beyond the trigeminal ganglion the trigeminal nerve divides into three major branches or nerves:
- ophthalmic nerve (CN V1),
- maxillary nerve (CN V2),
- mandibular nerve (CN V3).