Trigeminal Nerve(v)

Trigeminal nerve(V) It has three divisions 1.ophthalmic(V1) 2.maxillary(V2) 3.mandibular(V3) The first two are purely sensory Mandibular is a mixed nerve.

Its motor nucleus is in the pons which supplies the muscles derived from I arch Functional components GSA SVE(to masticatory muscles)

Nuclei: the principal sensory nucleus is in the pons Which sends extensions into midbrain(mesencephalic nucleus of V) and into spinal cord through medulla(spinal nucleus and tract of V)

1.mesencephalic nucleus of V 2.pontine nucleus 3.motor nucleus, 4.spinal nucleus and tract

It is the sensory nerve of the face and Nerve of the I arch

The trigeminal nerve functions in sensing facial touch, pain and temperature, as well as controlling muscles of mastication

Superficial attachment of Vnerve

Foramina of exit Ophthalmic nerve (superior orbital fissure) Maxillary nerve(foramen rotundum) Mandibular nerve(foramen ovale)

FORAMINA OF EXIT V1

V2

V3

Testing the trigeminal nerve Facial sensation and chewing Sensation in areas of the face is tested by using a pin and a wisp of cotton. (ophthalmic)

Testing the trigeminal nerve

The blink reflex is tested by touching the cornea of the eye with a cotton wisp.(ophthalmic)

Testing the trigeminal nerve Strength and movement of muscles of mastication are tested(V3) by asking the person to clench the teeth and open the jaw against resistance.

Two disorders that affect the trigeminal nerve and ganglion are herpes zoster (= shingles) trigeminal neuralgia (= tic douloureux). Both cause pain. Usually one of the three divisions is involved.

Facial nerve(VII)(nerve of II arch) Motor nerve of the face Nerve of second arch Carries taste from the anterior 2/3 of the tongue Carries secretomotor fibers to submandibular and sublingual salivary glands, lacrimal gland, glands of the nose,palate.

Functional components: 1.SVE (to the muscles of second arch) 2.SVA (taste) 3.GVE (parasympathetic fibers), 4.SA(small area of pinna)

Nuclei 1.Motor nucleus is in the pons. Taste goes to 2.nucleus of tractus solitarius in the medulla From the small area of the pinna sensations go to 3.Spinal nucleus of trigeminal nerve. 4.Parasympathetic nucleus is called superior salivatory nucleus.

Facial nerve at ponto medullary junction

It leaves the cranial cavity(!) through the internal acoustic meatus enters the petrous temporal.

Petrous temporal(Lt)

exits the skull through the stylomastoid foramen then enters the parotid gland Here it divides into its terminal branches which spread out To supply the muscles of facial expression.

Stylomastoid foramen

Clinical aspects

Upper Motor Neuron (UMN) Lesion

Results from damage to neuronal cell bodies in the cortex or their axons that project to the motor nucleus of CN VII.

With an UMN lesion, voluntary control of only the lower muscles of facial expression on the contralateral side to the lesion will be lost.

Voluntary control of muscles of the forehead will be spared due to the bilateral innervation of the the upper muscles of facial expression.

Upper half of face is spared

Bilateral representation

How shall I know UMN or LMN lesion?

•Atrophy of muscles of lower portion of the face on affected side* •No eyebrow droop* !!

•Intact folds on forehead* Only in UMN

Bell’s palsy  Lower

Motor Neuron (LMN) Lesion

Results from damage to the motor nucleus of CN VII or its axons. A LMN lesion results in the paralysis of all muscles of facial expression (including those of the forehead) ipsilateral to the lesion.

Bell’s palsy

Facial nerve testing VII

Facial

Facial expression and taste in the front two thirds of the tongue

The ability to move the face is tested by asking the person to smile, to open the mouth and show the teeth, and to close the eyes tightly. Taste is tested using substances that are sweet (sugar), sour (lemon juice), salty (salt), and bitter (aspirin, quinine, or aloes).

Vestibulo cochlear nerve(VIII)  Purely

sensory  Has cochlear part(hearing) and vestibular part(for balance)

Vestibular part begins from the semicircular canals and vestibule of the internal ear. Cochlear part from the organ of corti in the internal ear.

the nerve then travels through the internal auditory meatus with the facial nerve.

*enters the brain stem at the junction of the pons and medulla lateral to the facial nerve.

The auditory part ends in a sensory nucleus called the cochlear nucleus. which is located at the junction of the pons and medulla.

The Vestibular part of the eight nerve ends in the Vestibular nuclear complex located in the floor of the fourth ventricle.

Testing the VIII nerve

VIII

Acousti Hearing and c balance

Hearing is tested with a tuning fork. Balance is tested by asking the person to walk a straight line.

Damage to the Vestibular nucleus leads to: vertigo (violent spinning sensation) (often with initial vomiting) dizziness, and difficulties with balance, vision, or hearing may result.

Sometimes the symptoms can be so severe that they affect the ability to sit up, stand, or walk. There may also be tinnitus (ringing or noises in the ear) and/or hearing loss.