Trigeminal nerve


Composed of three large branches: the ophthalmic (V1, sensory), maxillary (V2, sensory) and mandibular (V3, motor and sensory) branches.

Trigeminal nerve

The fifth cranial nerve.

A nerve responsible for sensation in the face and motor functions such as biting and chewing.

The largest of the cranial nerves.

Each of the two nerves, one on each side of the pons, has three major branches: the ophthalmic nerve (V1), the maxillary nerve (V2), and the mandibular nerve (V3).

The ophthalmic and maxillary nerves are purely sensory, whereas the mandibular nerve supplies motor as well as sensory functions.

The motor division of the trigeminal nerve is derived from the embryonic pons, and the sensory division originates in the cranial neural crest.

Sensory information from the face and body is processed by parallel pathways in the central nervous system.

From the trigeminal ganglion a single, large sensory root enters the brainstem at the level of the pons, and adjacent to the sensory root, a smaller motor root emerges from the pons at the same level.

Motor fibers pass through the trigeminal ganglion on their way to peripheral muscles, but their cell bodies are located in the nucleus of the fifth nerve, deep within the pons.

The areas of the dermatomes of the three branches of the trigeminal nerve have sharp borders with relatively little overlap.

The injection of a local anesthetic results in the complete loss of sensation from well-defined areas of the face and mouth.

Teeth on one side of the jaw can be numbed by injecting the mandibular nerve.

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.

The ophthalmic, maxillary and mandibular branches leave the skull through three separate foramina: the superior orbital fissure, the foramen rotundum and the foramen ovale, respectively.

The ophthalmic nerve (V1) 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, the frontal sinuses and parts of the meninges.

The maxillary nerve (V2) 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 (V3) carries sensory information from the lower lip, the lower teeth and gums, the chin and jaw, parts of the external ear and parts of the meninges.

The angle of the jaw, which is supplied by C2-C3.

The mandibular nerve carries touch-position and pain-temperature sensations from the mouth, but does not carry taste sensation.

One of the branches of the mandibular nerve, the lingual nerve carries sensation from the tongue.

One of the mandibular nerve breaches, the lingual nerve, carries sensation from the tongue.

The trigeminal nerve provides tactile, proprioceptive, and nociceptive afferent sensory function to the face and mouth.

The trigeminal nerve motor function activates the muscles of mastication, the tensor tympani, tensor veli palatini, mylohyoid and the anterior belly of the digastric.

The trigeminal nerve carries general somatic afferent fibers which innervate the skin of the face via ophthalmic (V1), maxillary (V2) and mandibular (V3) divisions.

The trigeminal nerve also carries special visceral efferent axons, which innervate the muscles of mastication via the mandibular (V3) division.

The mandibular division (V3) of the trigeminal nerve controls the movement of eight muscles, including the four muscles of mastication: the masseter, the temporal and the medial and lateral pterygoids, and the other four muscles are the tensor veli palatini, the mylohyoid, the anterior belly of the digastric and the tensor tympani.

With the exception of the tensor tympani, all these muscles are involved in biting, chewing and swallowing and all have bilateral cortical representation.

A unilateral central lesion, no matter how large, is unlikely to produce an observable deficit.

Injury to a peripheral nerve can cause paralysis of muscles on one side of the jaw, with the jaw deviating towards the paralyzed side when it opens.

All sensory information of the trigeminal nerve is sent to specific nuclei in the thalamus, and then to specific areas in the cerebral cortex.

The secondary neurons in each pathway decussate.

Decussated fibers later reach and connect these segments with the higher centers.

The optic chiasm is the primary site of decussation.

The nasal fibers of the optic nerve cross to keep the interneuronal connections responsible for processing information short.

All sensory and motor pathways converge and diverge to the contralateral hemisphere.

Touch-position information from the face is carried to the thalamus by the trigeminal lemniscus

Pain-temperature information from the face is carried to the thalamus by the anterior division of the trigeminal lemniscus.

From the thalamus, touch-position and pain-temperature information is projected onto the cerebral cortex.

The trigeminal nucleus receives all of the sensory information from the face, both touch-position and pain-temperature, is sent to the trigeminal nucleus.

However, sensation from parts of the mouth, parts of the ear and parts of the meninges is carried by general somatic afferent fibers in cranial nerves VII (the facial nerve), IX (the glossopharyngeal nerve) and X (the vagus nerve) that terminate in the trigeminal nucleus.

Sensory fibers from V, VII, IX and X are sorted in the brainstem and sent to the trigeminal nucleus.

The trigeminal nucleus contains a sensory map of the face and mouth.

The trigeminal nucleus extends throughout the brainstem, from the midbrain to the medulla, continuing into the cervical cord.

The trigeminal nucleus is divided into three parts microscopically: the spinal trigeminal, the principal sensory and the mesencephalic nuclei.

The spinal trigeminal nucleus receives pain-temperature fibers, the principal sensory nucleus receives touch-position fibers and the mesencephalic nucleus receives proprioceptor and mechanoreceptor fibers from the jaws and teeth.

The spinal trigeminal nucleus contains a pain-temperature sensory map of the face and mouth.

The principal nucleus of the trigeminal nerve represents touch-position sensation from the face, and is located in the pons, near the entrance for the fifth nerve.

Touch-position information fibers from the face and mouth via cranial nerves V, VII, IX, and X are sent to this nucleus when they enter the brainstem.

The principal nucleus contains a touch-position sensory map of the face and mouth.

The principal nucleus is analogous to the dorsal column’s nuclei, the gracile and cuneate nuclei, of the spinal cord, which contain a touch-position map of the rest of the body.

Secondary fibers of the principal nucleus cross the midline and ascend in the ventral trigeminothalamic tract to the contralateral thalamus, running parallel to the medial lemniscus, which carries touch-position information from the rest of the body to the thalamus.

Touch-position information from the teeth and jaws of one side of the face is represented bilaterally in the thalamus and cortex.

Proprioceptor fibers from the jaw and mechanoreceptor fibers from the teeth have cell bodies in the mesencephalic nucleus, with some of these incoming fibers go to the motor nucleus of the trigeminal nerve, bypassing the pathways for conscious perception.

The jaw jerk reflex has incoming fibers from the teeth and jaws that go to the main nucleus of V.

The largest cranial nerve and is the great sensory nerve of the head and face, and the motor nerve of the muscles of mastication.

Emerges from the upper side of the pons, by a small motor and a large sensory root—the former being situated in front of and medial to the latter.

The ophthalmic nerve, or first division of the trigeminal nerve, is a sensory nerve that supplies branches to the cornea, ciliary body, iris, lacrimal gland and conjunctiva, to the mucous membrane of the nasal cavity, and to the skin of the eyelids, eyebrow, forehead, and nose.

The ophthalmic nerve is the smallest of the three divisions of the trigeminal, and just before entering the orbit, through the superior orbital fissure, it divides into three branches, lacrimal, frontal, and nasociliary.

The ophthalmic nerve communicates with the oculomotor, trochlear, and abducent nerves.

The lacrimal nerve is the smallest of the three branches of the ophthalmic.

The frontal nerve is the largest branch of the ophthalmic nerve.

The supratrochlear nerve supplies the skin of the lower part of the forehead close to the middle line and sends filaments to the conjunctiva and skin of the upper eyelid.

The supraorbital nerve supplies the integument of the scalp.

The nasociliary nerve supplies the skin of the ala and apex of the nose.

Its roots are three in number.

The first, the long or sensory root, is derived from the nasociliary nerve, and joins its postero-superior angle.

The second, the short or motor root, is a thick nerve derived from the branch of the oculomotor nerve to the Obliquus inferior, and connected with the postero-inferior angle of the ganglion.

The motor root contains sympathetic efferent fibers from the nucleus of the third nerve in the mid-brain to the ciliary ganglion where they form synapses with neurons whose fibers pass to the Ciliary muscle and to Sphincter muscle of the pupil.

The third is the sympathetic root, Its branches are the short ciliary nerves.

The Maxillary nerve or second division of the trigeminal, is a sensory nerve, which spread out upon the side of the nose, the lower eyelid, and the upper lip, joining with filaments of the facial nerve.

The Maxillary nerve branches may be divided into four groups, according as they are given off in the cranium, in the pterygopalatine fossa, in the infraorbital canal, or on the face.

In the Cranium-Middle meningeal.

In the Pterygopalatine Fossa-Zygomatic, Sphenopalatine, Posterior superior alveolar.

In the Infraorbital Canal-Anterior superior alveolar, Middle superior alveolar.

On the Face-Inferior palpebral, External nasal, Superior labial.

The Middle Meningeal Nerve is given off from the maxillary nerve directly after its origin from the semilunar ganglion; it accompanies the middle meningeal artery and supplies the dura mater.

The Zygomatic Nerve arises in the pterygopalatine fossa, enters the orbit by the inferior orbital fissure, and divides at the back of that cavity into two branches, zygomaticotemporal and zygomaticofacial.

The mandibular nerve supplies the teeth and gums of the mandible, the skin of the temporal region, the auricula, the lower lip, the lower part of the face, and the muscles of mastication; it also supplies the mucous membrane of the anterior two-thirds of the tongue.

As a general rule the diffusion of pain over the various branches of the nerve is at first confined to one only of the main divisions, and the search for the causative lesion should always commence with a thorough examination of all those parts which are supplied by that division; although in severe cases pain may radiate over the branches of the other main divisions.

The commonest example of the diffusion of pain is the neuralgia which is so often associated with dental caries.

The tooth itself may not appear to be painful, the most distressing ref2242ed pains may be experienced, and these are at once relieved by treatment directed to the affected tooth.

Other examples of trigeminal reflexes inclide: ophthalmic nerve, severe supraorbital pain is commonly associated with acute glaucoma or with disease of the frontal or ethmoidal air cells, malignant growths or empyema of the maxillary antrum, or unhealthy conditions about the inferior conchæ or the septum of the nose, are often found giving rise to neuralgia, and should be always looked for in the absence of dental disease in the maxilla.

The mandibular nerve reflexes are seen with patients who complain of pain in the ear, in whom there is no sign of aural disease, and the cause is usually to be found in a carious tooth in the mandible.

With a lesion of the tongue, often the first pain to be experienced is one which radiates to the ear and temporal fossa, over the distribution of the auriculotemporal nerve.

The mandibular nerve innervates the mylohyoid muscle and the anterior belly of the digastric which are mastication muscles.

The mandibular nerve also innervates the tensor veli palatini and tensor tympani muscles.

The three sensory branches of the trigeminal nerve emanate from the ganglia to form the three branches of the trigeminal nerve.

The ophthalmic and maxillary branches travel through the wall of the cavernous sinus prior to leaving the skull, and the ophthalmic branch travels through the superior orbital fissure through the orbit to innervate the skin of the forehead and top of the head.

The maxillary nerve enters the skull through the foramen rotundum via the pterygopalatine fossa and its sensory branches reach the pterygopalatine fossa via the inferior orbital fissure with innervation to face, cheek and upper teeth and via the pterygopalatine canal innervating the soft and hard palate, nasal cavity and pharynx.

The meningeal sensory branches that enter the trigeminal ganglion within the skull.

The sensory part of the mandibular nerve is composed of branches that carry general sensory information from the mucous membranes of the mouth and cheek, anterior two-thirds of the tongue, lower teeth, skin of the lower jaw, side of the head and scalp and meninges of the anterior and middle cranial fossae.

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