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Flashcards in Cranial Nerves Deck (94):
1

12 cranial nerves

functionally similar to spinal nerves

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Cranial nerves

1. in brainstem
2. innervate muscles of head, neck, face, larynx, tongue, pharynx, & glands
3. Essential for speech, resonance, & phonation, swallowing, vagus

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Optic nerve attachment to retina creates a ??

blind spot

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CN I

olfactory nerve: sensation of smell

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CN II

optic nerve: visual sensation

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CNIII

oculomotor nerve: motor nerve, eyeball movement

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CN IV

trochlear nerve: motor nerve, eyeball movement

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CN V

trigeminal nerve: sensory (head, face, oral) and motor (jaw movement)

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CN VI

abducens: motor nerve, eye movement through lateral rectus muscle

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CN VII

facia: primarily motor, muscles of face, sensory-taste

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CN VIII

vestibulocochear: sensory: equilibrium and hearing

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CN IX

glossopharyngeal: motor (swallowing) and sensory (touch & taste from posterior third of tongue and pharynx)

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CN X

Vagus: motor and sensory for pharynx, larynx, and soft palate

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CN XI

spinal accessory: motor nerve
-muscles contolling head movement

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CN XII hypoglossal nerve

motor nerve for muscles of tongue

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Cranial nerve nuclei: midbrain 3 nuclei

1. edinger-westphal nucleus
2. oculomotor nucleus
3. trochlear nucleu

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Pons: 7 major nuclei

Trigeminal nerve, primary nucleus (spinal trigeminal and mesencephalic nuclei), abducens motor, and facial

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Medulla: 9 major nuclei

1. cochlear and vestibular nuclear complexes
2. solitarius nucleus
3. salivatory nucleus (ANS)
4. hypoglossal nucleus
5. ambiguus nucleus
6. spinal trigeminal nucleus

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Corticonuclear (bulbar fibers)

cortex to brainstem

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Corticonuclear fibers

UMNs, LMNs
-Descend through internal capsule-genu

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Sensory Pathways

three-order nuclei & fibers (moving from lower to upper)

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first-order fibers

outside the CNS (tickle on the face)

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Second-order fibers

brainstem gray matter: ducussating second-order fibers (right cheek tickle meets up w/ left cheek thalamus and crosses)

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Third-order fibers

projections from the thalamus to the sensory cortex

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UMNs

syndromes affect nerves from cortex to brainstem

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LMNs

brainstem to face

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3 sensory pathways (first, seond, third) and how many motor?

2: UMN and LMN

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Complex Motor Innervation/Bilateral corticonuclear innervation

facial, trigeminal, vagus, glossopharyngeal

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Complex/BilateralFacial innervates

upper face

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Trigeminal innervates

masticators

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Vagus innervates

pharynx & larynx

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Glossopharyngeal innervates

pharynx

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Unilateral corticonuclear innervation

facial, spinal accessory, hypoglossal, ocular muscles (oculomotor, trochlear, abdusence)

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Unilateral facial innervates

lower facial muscles

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Spinal accessory innervates

Sternocleidomastoid and trapezius muscles

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Hypoglossal innervates

lingual muscles

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oculomotor, trochlear, and abdusence innervate

ocular muscles

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Conjugate gaze center

cortinoculear projections for the coordination of both eyes

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Trigeminal nerve Function

sensory- face, head, oral, orbital cavities
motor-muscles of mastication/chewing

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Trigeminal nerve structures/complex

1. primary sensory nucleus
2. spinal nucleus
3. mesencephalic nucleus

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Sensory portion of trigeminal nerve

1. thalamic
2. maxillary
3. mandibular

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2nd order neurons of trigeminal

1. principle trigeminal nucleus
2. mesencephalic
3. spinal trigeminal

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principle trigeminal nucleus

TOUCH
-most cross contralateral thalamuc nucleus
-some sensory info from teeth and jaws goes to thalamus

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mesencephalic

PROPRIOCEPTION
-bilateral: biting, chewing, swallowing are all symmetrical

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spinal trigeminal

PAIN
-contralateral thalamus

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Clinical probs w/ Trigeminal Nerve

1. Trigeminal neuralgia
2. Peripheral branch damage
3. Special Visceral (Branchial) Efferent
4. Motor Nucleus damage
5. Unilateral cortical or corticonuclear injury
6. Bilateral cortical (UMN) or LMN lesion

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Trigeminal neuralgia

tic douloureux-chronic pain sensation of unknown etiology

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Sensation/touch damage to Peripheral branch

Ipsilateral loss of sensation-face, tongue, teeth, mouth, gum & cavities oral/orbital

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Testing Peripheral branch damage

Stimuli of cotton, pin prick, & reflexes (sneeze & corneal)

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Special Visceral (Branchial) Efferent/ damage to Trigeminal

motor nucleus, masticators, Tensor veli palatini (preventing food from nasopharynx) and tensor tympani (restricting malleus motion on exposure to loud sound)

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Motor nucleus damage/ Trigeminal nerve

LMN syndrome: paralysis of ipsilateral masticators w/ jaw deviation to site of injury: deviation obvious upon jaw protrusion
-muscles twitch, gradually atrophy, and jerk/reflex absent

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Unilateral cortical or corticonuclear injury has mild effect on jaw strength/trigeminal nerve

due to bilatera innervation

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Bilateral control (UMN) or LMN lesion/Trigeminal nerve damage

bilateral jaw paralysis

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Testing trigeminal nerve damage for motor damage

lateral & frontal jaw movement against resistance, also can be test phones requiring jaw support (bilapials, labiodental, dentals, and palatals)

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Facial Nerve Function

Motor: muscles of face, scalp & stapeius: kissing, blowing, speaking, smiling, raising, eyebrows, emotional expressions, and swallowing

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Facial Nerve Function #2

Superior salivatory: paraysympathetic efferent to lacrimal, sublingual & submandibular glands & secretory glands in mouth & nasal cavities

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Facial Nerve function #3

Sensory: Nucleus Solitarius: Taste sensation: anterior 2/3 of the tongue

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Facial Innervation: corticobulbar

1. lower face
2. upper face

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Frontal Innervation: lower face

contralateral innervation

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Frontal innervation: upper face

bilateral innervation

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Clinical Implications w/ UMN

paralysis in contralateral lower half of face w/ spared upper face

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Clinical implications w/ LMN or bilateral cortical lesion:

paralysis of upper & lower face

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Clinical correlates w/ Facial Nerve damage
#1:

Pons-affect all 3 (general visceral efferent, special visceral afferent, and special visual efferent) functions

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Clinical correlates w/ Facial Nerve damage #2:

Facial nerve beyond stylomastoid forament: paralysis of ipsilateral half of facial muscles, intact glandular secretion & taste sensation

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Clinical correlates w/ Facial Nerve damage #3:

General Visceral Efferent fibers: secretory dysfunctions of glands in eye & palate

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Clinical correlates w/ Facial Nerve Damage #4:

Interruption of efferents to middle ear-hyperacusia (normal sounds seem louder)

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Bells Palsy: facial nerve dysfunction

Lower Motor Neuron Syndrome: sudden onset of paralysis of ipsilateral upper and lower facial muscles

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Bells Palsy etiology

nerve degeneration, inflammation or infection of facial nerve

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Testing facial nerve damage by asking patient to

smile, part lips, show teeth, puff out cheeks, pucker lips, express emotions
-taste eval: salt, sugar, vinegar

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Vestibulochoclear Nerve Function

equilibrium and audition

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Vestibular nerve Fx: Special Somatic Afferent

maintains equilibrium, coordination of head and body, stabilization of visual fixation point during movement

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first order vestibular

superior & inferior vestibular ganglia

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second order vestibular

nuclei in caudal pons

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projections to ???/vestibular

MLF/ocular fixation & cerebellum/equilibrium

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Scarpas ganglion

nucleus for vestibular nerve/first order

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Auditory nerve

bilateral projections to cortex and tonotopic representation throughout path and auditory cortex-equally important descending fibers

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First order auditory nerve

spiral ganglia

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second order auditory nerve

cochlear nuclei in caudal pons

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***3rd order is always the same: always goes to motor cortex!***

ALWAYS GOES TO MOTOR

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Clinical correlates of vestbulacochlear nerve

equilibrium and audition

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Equillibrium of vestibulacoch

disturbances of equilibrium and impaired vertigo/dizziness

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Audition of vestibulocohelaer

conductive or sensorineural hearing loss, brainstem lesion-partial impariment (bilateral projections)

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Glossopharyngeal nerve function

functionally identical to vagus nerve

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Sensorimotor nucleus of glossopharyngeal nerve

1. inferior salivatory nucleus
2. nucleus ambiguus
3. nucleus solitarius

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glossopharyngeal and vagus share a ?

ganglion-functionally same

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glossopharyngeal first order

inferior ganglion

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glossopharyngeal second order

nucleus solitarius

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glossopharyngeal

VPM of thalamus

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General Visceral Afferent of Glossopharyngeal

inputs from carotid body (chemoreceptors) in response to changes in blood carbon dioxide help control respiration rate
-carotid sinus baroreceptors respond to increased blood pressure and control blood flow

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3. Nucleus Solitarius of glossopharyngeal

taste sensation from posterior third of tongue and oral pharynx

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1. Inferior Salivatory Nucleus of glossopharyngeal

controls glands and cardiac muscles, regulates secretion from parotid gland and secretion from oral pharynx
-preganglionic parasympathetic projections to inferior salivatory nucleus
-postganglionic projections to otic ganglion (parotid secretion)

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2. Nucleus Ambiguus (branchial branch) of glossopharyngeal

nucleus ambiguus is rostral, bilaterally innervated, and regulates swallowing by projections to (ipsilateral stylopharyngeal muscle, upper pharyngeal constrictor fibers)

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Clinical correlates to glossopharyngeal

1. discrete lesion
2. loss of taste
3. loss of gag reflex
4. excessive oral secretion

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discrete lesion of glossopharyngeal

partial paresis of unilateral stylopharyngeal muscle (impairment of ipsilateral pharyngeal elevation in deglutition)