CN 5 Flashcards by Maddy Meyer

Largest CN?

Trigeminal

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CN has a _____ motor portion and ______ sensory

Small, large

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V1-ophthalmic- M/S?

Sensory

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V2-maxillary-M/S?

Sensory

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V3-mandibular-M/S?

Both

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CN fibers originate in _____ _____ and descend in _____ ______ to ______ nucleus in the ________

Precentral gyrus
Descend in corticobulbar tract
To motor nucleus

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Trigeminal motor nucleus receives projections from where?

Both cerebral hemispheres

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Motor root exits _______ ______ and passes beneath _____ _____ and exits skull through _____ _____

Lateral pons
Trigeminal ganglion
Foramen ovale

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What does the motor (V-3) pathway supply?

Muscles of mastication (temporalis, masseter, med/lat pterygoid)

Tensor tympani, tensor evil palatine, mylohyoid, anterior belly of digastric

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Because trigeminal motor nucleus receives projections from both hemispheres, if there was a lesion on one side, what will the affects be?

Not much affect-redundancy

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Function of temporalis

Close jaw

Retract

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Internal/medial pterygoid function

Syncs: close and protrude
Unilateral: side to side jaw movement

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Masseter

Close and protrude

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External/lateral pterygoid

Sync: open and protrude jaw

Unilateral: pulls mandible contralaterally

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What does unilateral trigeminal motor weakness cause during opening?

Jaw to deviate toward the side of weakness

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If you had a weak right pterygoid what would you find?

Jaw deviates to the right on opening

Inability to move jaw to the left on command

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Unilateral weakness of CN5 signifies a lesion potentially where?

brain stem (dismally)
trigeminal ganglion
motor root of CN 5

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Will there be weakness with UMN lesion of CN5?

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Besides muscle weakness, what else might you find with a LMN lesion of CN 5

Atrophy
Fasciculations
Decreased jaw jerk reflex

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Atrophy of masseter

Flattening of jowl

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Atrophy of temporalis

Hallowing of the temple on ipsilateral Sid

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Severe bilateral weakness of muscles of mastication with inability to close mouth suggest

Bilateral corticobulbar lesions

motor neuron disease (ALS)
neuromuscular transmission disorder (MG)
myopathy

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CN V1,2,3 converge on trigeminal ganglion aka _____ aka ______ ganglion located in _____ ______

Semilunar
Gasserian
Meckel’s cave

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After converging at the trigeminal ganglion, a large sensory root of trigeminal nerve enters brainstem at the _______. Some _____ their branches and terminate on the ____ ______ nucleus and others ______ and terminate in the _____ _____

Pons
Ascend and terminate on main sensory nucleus
Descend and terminate in the spinal nucleus

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Fibers with what sensations terminate in the main sensory nucleus

Touch and pressure

Fibers with what sensations pass to the spinal nucleus

Pain and temperature

From the main sensory and spinal nuclei axons ascend in the _____ and _____ ______ ______ to the ____ ____ ___ _____ nucleus

Dorsal and ventral trigeninothalamic tract | Ventral posterior medial (VPM) thalami nucleus

Once ascending to the VPM, fibers project to the _____ cortex in the ____ ___ ____

Sensory | Post central gyrus

What does CN v-1 supply?

``` Bridge and side of nose upper eyelid forehead scalp to vertex eyeball-superior 1/2 cornea Lacrimal gland Nasal septum Lateral wall of nasal cavity Ethmoid sinus Tentorium cerebelli ```

What does CN 5-2 supply

``` Cheek Lateral forehead Side of nose Upper lip Upper teeth/gums Palate Nasopharynx Posterior nasal cavity Meninges of anterior/middle cranial fossa ```

What does CN 5-3 sensory part supply

``` Inner cheek Temple Lateral scalp EAM tympanic membrane TMJ Mandible Lower teeth/gums Anterior 2/3tongue (GEN SENSORY) Lower lip Chin Anterior and middle cranial fossa ```

Does CN 5-3 supply sensory innervation to the angle of the jaw?

Sensory fibers from where synapse in the inferior (caudal) aspect of the spinal nucleus?

pre-auricular

Sensory fibers from where synapse in the middle aspect of the spinal nucleus?

Middle ring of the face

Sensory fibers from where synapse in the superior/rostral aspect of the spinal nucleus?

Perioral ring

If patient presents with unilateral or bilateral onion skin distribution of sensory loss it suggests a lesion where?

Spinal nucleus. Outer face—lower parts of spinal nucleus Inner face—upper part of spinal nucleus

Lesions distal to trigeminal ganglion will involve what?

Isolated divisions ex: V1,2,3

Lesions central to the trigeminal ganglion will affect what

All 3 branches of sensory distribution of CN 5

Lesions involving the spinal nucleus of the brainstem will cause what

Sensory dysfunction in an “onion skin” appearance

CN 7 function types

Parasympathetic Visceral sensory General somatosensory

Parasympathetic innervation to what CN7

Tears and saliva

Visceral sensory function of CN7

Taste (ant 2/3)

CN 7. Main trunk carries ____ _____ fibers that control ____ ____ and smaller branchL ____ ____ carries fibers for ______, _____ ____, and _____ _____

Brachial motor that control facial expression Nervous intermedius Parasympathetic, visceral sensory and general somatosensory function

CN 7 path. Primary motor cortex in ____ _____. ________ tracts descend to ____ _____ in ______ and synapse with _______

Precentral gyrus in corticobulbar tracts Descend to facial nucleus in pons Synapse with LMNs’ (facial N)

Facial N exits ____ at ______ _____ and transverse ____ _____ and enters the ____ ____ ____ and travels in the _____ _____ with CN ____

Brainstem at cerebellopontine angle Transverse subarachnoid space Enter the internal AM Travels in auditory canal with CN 8

After CN 7 travels in auditory canal with CN8, it runs inferiorly in the ____ ___. The main portion then ______ the skull through the ______ ____ and passes through the _____ _____. Here it divides into _____ major ____ _____ branches to supply ______ of facial expression

Facial canal Exits skull through stylomastoid foramen Pass through parotid gland Divides into 5 brachial motor branches Supply muscles of facial expression

What muscles of facial expression does CN 7 supply

- frontalis - orbicularis oculi/oris - buccinator - platysma - posterior/digastric - stapedius muscle

What does the platysma do

Frown

What does the stapedius muscle do

Dampens movement of middle ear ossicles -protective mechanism of sound at loud events

Preganglionic fibers of CN7 originate in the ____ ____ ____ and branch into ___ nerves: ____ ___ and _____ ____

Superior Salvatore nucleus 1. Greater petrosal 2. Chorda tympani

Greater petrosal nerve goes through ___ ganglion and has ____ _____ fibers to the _____ ___ and ____ ___

Sphenopalatine ganglion Postganglionic parasympathetic fibers to lacrimal gland and nasal mucosa

Chorda tympani exits skull through ____ ____ and joins ___ ___ to reach ______ ganglion. Has ____ ____ supply to ____ and ____ _____ glands

Petrotympanic fissure Joints lingual nerve to reach submandibular ganglion Postganglionic parasympathetic supply to submandibular and sublingual salivary glands

Submandibular and sublingual glands receive parasympathetic innervation from? And sympathetic?

Para: chorda tympani Symp: superior cervical ganglion and carotid plexus

Sympathetic innervation causes what from submandibular/sublingual glands?

Vasoconstriction and scant, thick, mucoid secretion low in enzyme

Lesion in internal acoustic meatus would cause what.

Look up! Slide 42

Visceral sensory pathway for CN7. ______ _____ carries fibers from ant 2/3 tongue that has cell bodies in the _____ ganglion. It synapses with secondary neurons in the ____ _____/_____ _____ and ascends via ____ ______ tract where it reaches the _______ and these neurons protect to _____ ___ ____ in the ______ gyrus

Chorda tympani Geniculate Nucleus solitaries/gustatory nucleus Ascends via central tegmental tract and reaches the VPM nucleus Project to cortical taste area in the postcentral gyrus

General somatosensory pathway of CN7. Primary sensory neurons located in _____ ganglion and synapse in the _____ nucleus where they then continue to the ______ cortex in the ______ gyrus

Geniculate Synapse in trigeminal nucleus Somatosensory cortex in the postcentral gyrus

Where does the facial nerve provide somatic sensation

Region near the EAM

UMN lesion in CN7 cause what?

Contralateral face weakness sparing the forehead **recall upper face has both hemispheres contributing and unaffected hemisphere can compensate

Where could the lesion be if there is left sided facial weakness—sparing the forehead?

CN 7 UMN lesion on the R

Where could the lesion be if the entire left side of the face is weak?

CN7 LMN lesion on the left

What part of the face has innervation from both hemispheres?

Upper part—forehead Why UMN lesion results in sparing of the forehead, and LMN lesion doesn’t

What pathology cause loss of facial movement on entire side of face

Bell’s palsy-LMN issue

What pathology causes facial weakness sparing the forehead?

Stroke—UMN lesion

What should be considered if patient can raise both eyebrows?

Stroke

Two types of lesions of CN7

Peripheral/nuclear/infranuclear (Aka at nucleus or below) Central/supranuclear

Where is the lesion in CN7 in a peripheral lesion?

From the facial nucleus and distal

S/s of peripheral/nuclear/infranuclear lesion of CN7

Ipsilateral to lesion - complete facial paralysis - smoothening of brow - difficulty closing eye - flat nasolabial fold - drooping of mouth

Where might the lesion be in a central/supranuclear lesion of CN 7

Lesion of motor cortex or corticobulbar tracts

S/s of central/supranuclear lesion of CN7

- contralateral to lesion - lower portion of face - spare forehead/can raise eyebrow - drooping mouth - flattened nasolabial fold

The 5Ds. 3Ns, and A for stroke

D: dysarthria, dysphasia, diplopia, dizziness, drop attacks N: numbness, nystagmus, nausea A: Ataxia

Aguesia

Complete loss of taste

Cause of aguesia

Olfaction dysfunction (Vit A, b6,12,zinc,copper def) - viral infection - aging - toxic - metabolic

Unilateral deficits in taste causes?

Lesions of nucleus solitarious or facial nerve ** if peripheral lesion it must be proximal to stylomastoid foramen because if distal would only affect muscles

Lesion distal to stylomastoid foramen would cause what>

Weakness of muscles of facial expression