Cranial NervesII

8/14/2019 Cranial NervesII

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Trigeminal nerve(V)Trigeminal nerve(V)

It has three divisionsIt has three divisions

1.ophthalmic(V1)1.ophthalmic(V1)

2.maxillary(V2)2.maxillary(V2)3.mandibular(V3)3.mandibular(V3)

The first two are purely sensoryThe first two are purely sensory

Mandibular is a mixed nerve.Mandibular is a mixed nerve.


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Its motor nucleus is in the pons

which supplies the muscles derived from I arch

Functional components

GSA

SVE(to masticatory muscles)


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uclei: the principal sensory nucleus is

in the pons

Which sends extensions into

midbrain(mesencephalic nucleus of V)

and

into spinal cord through medulla(spinalnucleus and tract of V)


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1.mesencephalic nucleus of V

2.pontine nucleus

3.motor nucleus,

4.spinal nucleus and tract


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It is the sensory nerve of the face

and

Nerve of the I arch


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The trigeminal nerve functions inThe trigeminal nerve functions insensing facial touch,sensing facial touch,

pain and temperature,pain and temperature,as well as controlling muscles ofas well as controlling muscles of

masticationmastication


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Superficial attachment of Vnerve


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Foramina of exit

Ophthalmic nerve (superior orbital fissure)

Maxillary nerve(foramen rotundum)

Mandibular nerve(foramen ovale)


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V1

V2

V3

FORAMINA OF EXITFORAMINA OF EXIT


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Facial sensation and chewing

Sensation in areas of the face is testedby using

a pin and a wisp of cotton. (ophthalmic)

Testing the trigeminal nerveTesting the trigeminal nerve


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The blink reflex is tested bytouching the cornea of the eye

with a cotton wisp.(ophthalmic)


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Strength and movement of muscles of

mastication are tested(V3)by asking the person to clenchthe teeth

and open the jaw against resistance.


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Two disorders that affect the trigeminal nerve

and ganglion areherpes zoster (= shingles)

trigeminal neuralgia (= tic douloureux).

Both cause pain.

Usually one of the three divisions is involved.


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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.


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Functional components:

1.SVE (to the muscles of second arch)

2.SVA (taste)3.GVE (parasympathetic fibers),

4.SA(small area of pinna)


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Nuclei

1.Motor nucleus is in the pons.

Taste goes to

2.nucleus of tractus solitarius in the medullaFrom the small area of the pinna sensations go to

3.Spinal nucleus of trigeminal nerve.

4.Parasympathetic nucleus is called

superior salivatory nucleus.


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Facial nerve at ponto medullary junction


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It leaves the cranial cavity(!)

through the internal acoustic meatus

enters the petrous temporal.


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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 facialexpression.


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Stylomastoid foramen


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Clinical aspectsClinical aspects


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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.


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With an UMN lesion,

voluntary control ofonly the

lower muscles of facial

expression on the contralateral

side to the lesion will be lost.


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Voluntary control ofmuscles of

the forehead will be spared

due to the bilateral innervationof the the upper muscles of

facial expression.


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Upper half of face is spared


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Bilateral representation


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Atrophy of muscles oflowerportion of the face on affectedside*

No eyebrow droop*

Intact folds on forehead*

!!

How shall I know UMN or LMN lesion?

Only in UMN


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Bells palsyBells palsy

Lower Motor Neuron (LMN) LesionLower Motor Neuron (LMN) Lesion

Results from damage to the motor nucleus ofResults from damage to the motor nucleus of

CN VII or its axons.CN VII or its axons.

A LMN lesion results in the paralysis of allA LMN lesion results in the paralysis of all

muscles of facial expression (muscles of facial expression (including thoseincluding those

of the foreheadof the forehead) ipsilateral to the lesion.) ipsilateral to the lesion.


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Bells palsy
http://images.google.com/imgres?imgurl=http://www.lyme.org/img/gallery/facialschwartz.jpg&imgrefurl=http://www.lyme.org/gallery/facialschwartz.html&h=277&w=437&sz=17&tbnid=V0zPAuW4jPXyAM:&tbnh=77&tbnw=123&hl=en&start=9&prev=/images%3Fq%3Dfacial%2Bnerve%26svnum%3D10%26hl%3Den%26lr%3D%26rls%3DGGLG,GGLG:2005-20,GGLG:en


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VII Facial Facial

expression

and taste in

the front

two thirdsof the

tongue

The ability to move

the face is tested by

asking the person to

smile, to open the

mouth and show theteeth, 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).

Facial nerve testing


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Vestibulo cochlear nerve(VIII)Vestibulo cochlear nerve(VIII)

Purely sensoryPurely sensory

Has cochlear part(hearing) andHas cochlear part(hearing) and

vestibular part(for balance)vestibular part(for balance)


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Vestibular part begins from the

semicircular canals and vestibule of the

internal ear.

Cochlear part from the organ of corti in the

internal ear.


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the nerve then travels through

the internal auditory meatus

with the facial nerve.


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*enters the brain stem at the junction of

the pons and medulla

lateral to the facial nerve.


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The auditory part ends in a sensory nucleus called the

cochlear nucleus.which is located at the junction of the pons and medulla.


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The Vestibular part of the eight nerve ends

in the Vestibular nuclear complexlocated in the floor of the fourth ventricle.


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VIII Acousti

c

Hearing and

balance

Hearing is tested with

a tuning fork. Balanceis tested by asking the

person to walk a

straight line.

Testing the VIII nerve

VIII Acousti

c

Hearing and

balance

Hearing is tested with

a tuning fork. Balanceis tested by asking the

person to walk a

straight line.


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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.


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Sometimes the symptoms can be sosevere

that they affect the ability to sit up,

stand, or walk.

There may also betinnitus (ringing or noises in

the ear) and/or hearing loss.

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Cranial NervesII