NEURO LEC 8: CRANIAL NERVES Flashcards by Chavez Girls

How many cranial nerves come from the midbrain?

CN 3 and 4

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How many cranial nerves come from the pons?

CN 5, 6, 7, 8

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How many cranial nerves come from the medulla?

CN 9, 10, 11, 12

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Why are cranial nerve 1 and 2 susceptible to MS disease

They are innervated by oligodendricytes instead of schwann cells due to location (they don’t leave the CNS)

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What is the only sensory nerve that reaches the cortex WITHOUT going through the thalamus

olfactory

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define anosmia

loss of smell

remember much information related to taste is olfactory in origin

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Where does the optic nerve cross?

The optic chiasm

Note: the optic tract is between the chiasm and the brain

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if a lesion occurs on a R option nerve, what will the visual field look like?

right eye blind

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if a lesion occurs at the optic chiasm, how is the visual field impacted?

loss of lateral visual fields on both eyes

the lateral fields (temporal) cross over at chiasm

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If a lesion occurs on the R optic tract, how is the visual field impacted?

loss of left visual field on both eyes

the L temporal crosses over to R side and R nasal will stay ipsilateral, forming the tract together

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What nerve is responsible for pupil constriction AND orienting head and eyes (Saccadic, reflex neck movement)

Oculomotor CNIII

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if your optic nerve is intact, but your oculomotor nerve is impaired, will you see pupillary constriction?

oculomotor causes the constriction

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if your R optic nerve is impaired, and you shine light into the right eye will you see constriction? what happens if you shine it in the L eye?

R eye = neither eye constricts (cant sense the light and send to brain)

L = both eyes constrict bc L eye still able to sense and send info to brain, allowing oculomotor to constrict both

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The olfactory nerve exits from what foramen?

Cribiform plate

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The optic nerve exits from what foramen

Optic canal

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The occulomotor nerve exits what foramen

superior orbital fissue

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The trochlear nerve exits what foramen?

Superior orbital fissure

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The opthamalic branch of the trigeminal nerve exits from what foramen

superior oribital fissure

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The maxillary branch of the trigeminal nerve exits from what foramen

foramen rotundum

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the mandibular branch of the trigeminal nerve exits from what foramen

foramen ovale

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The abducens nerve exits from what foramen?

superior orbital fissure

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The facial nerve exits from what foramen?

auditory canal (Stylomastiod foramen)

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The vestibulocochlear nerve exits from what foramen?

auditory canal (stylomastoid)

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Glossopharyngeal nerve exits what foramen?

Jugular foramen

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The vagus nerve exits through what foramen?

Jugular foramen

The spinal accessory nerve EXITS through what foramen?

Jugular Foramen

The spinal accessory nerve ENTERS the skull through what foramen?

Foramen magnum

The hypoglossal nerve exits the skull from what foramen?

hypoglossal canal

Damage to the R optic tract after the optic chiasm will cause….

L sided homonymous hemianopsia (Blind in the left visual field of both eyes)

Damage to an optic nerve between the optic chasm and the eyeball will cause…

Ipsilateral blindness (full blindness of the eye on that side in both visual fields)

what muscles does the oculomotor nerve control?

4 extraocular muscles levator palpebrae (elevates eyelids)

parasympathetic fibers of the oculomotor nerve are responsible for what?

ciliary nerve causes pupillary light reflex

external strabismus is

CN III issue ipsilateral eye fixed in abduction

ipsilateral ptosis is

CN III issue paralysis of upper eyelid

diplopia is

CN III issue double vision

Ipsilateral pupil fully dilated is called

mydriasis

What nerve innervates the “superior oblique muscle” of the eye

Trochlear nerve adducts and depresses eye

if someone has issues with CN IV, what might their symptoms be?

double vision difficulty reading or descending stairs head tile to opposite side

what is the only cranial nerve that exits from the dorsum of the brainstem?

trochlear

what muscles does trigeminal innervate? what side would the jaw deviate to when closing if there was a lesion on the R?

deviate to the R because pterygoids do contralateral deviation, so if the right ones are weak, they couldn't push to left and counter it

The orbicularis oculi does what action, and what is its innervation?

Closes eyes -Facial nerve

describe the corneal blink reflex

trigeminal nerve triggered by tactile stimulation of cornea

The consensual blink response is activated by _______ (1st order neuron) and sent to the _______ (2nd order neuron) and passed through interneurons in the ________ to both ________ nerves in order to close both eyes

Trigeminal ganglion spinal Trigeminal nucleus reticular formation Facial Nerves aka when something is in one eye both eyes will blink

problem with a facial nerve will cause numbness of the ___ side of the face and mouth

same

trigeminal neuralgia

sharp shooting facial pain neuropathic pain set off by stimulation not normally painful NO sensory loss

What muscle does CN VI innervate?

lateral rectus m

try to list the motor, parasympathetic, somatic sensory and special sensory of the facial nerve

motor - eyes, lips, stapedius of ear parasympathetic - salivary, lacrimal and nasal glands somatic sensory - tongue, pharynx, skin near ear canal special - anterior 2/3 tongue to solitary

Cranial nerves are ____ motor neuron (PNS/CNS) what condition does this mimic? how is it different than a stroke

cranial - lower, PNS bells palsy (CN VII) a stroke affects CNS, which affects UMNL, affecting the lower half of the face, not the whole half

The superior colliculus is for _____ whereas the inferior colliculus is for _____

Vision Hearing

What is the fluid called inside of the vestibular apparatus?

Endolymph

What is the fluid called that separates the bony structures from the membranous labyrinth of the vestibular system?

Perilymph

Head movement causes movement of ____ which moves embedded hair cells to fire the vestibular branch of CN VIII

endolymph

Movement of the endolymph inside of the semicircular canals detects…

Rotational acceleration/deceleration

the utricle and saccule respond to head position relative to

gravity and linear acceleration/deceleration

What causes the depolarization of the cochlear nerve endings

Vibration of endolymph is detected by hair cells which depolarize and send signal to cochlear nerve endings to activate them

what three structures does the cochlear nuclei send information to?

reticular formation, inferior colliculus and medial geniculate body (thalamic relay station to primary auditory cortex) RIM

what three cortical areas process auditory

primary auditory cortex auditory association cortex (memories) wenickes area (language) PAW

CONDUCTIVE DEAFNESS

transmission of vibrations is prevented in the outer or middle ear (lots of ear wax)

sensorineural deafness

damage of receptor cells or the cochlear nerve (less common)

where is the cell bodies (vestibular ganglion) of the vestibular nerve?

internal auditory canal

what does glossopharyngeal do? its a mixed nerve...

motor fibers - stylopharyngeus (swallowing) parasympathetic fibers - salivary gland and carotid body and sinus somatosensory - soft palate, pharynx, post tounge afferent gag reflex

where is the info from the glossopharyngeal processed

in nucleus in medulla and upper cervical SC

What cranial nerve controls peristalsis inside the esophagus

vagus nerve

What nerve handles the lips closing when you put food in your mouth?

Facial nerve

What nerve closes the larynx when you swallow?

Vagus

What nerve triggers the swallowing reflex (afferent)?

Glossopharyngeal

Where are the cell bodies of the spinal accessory nerve found?

Ventral horn of C1-C4

What nerve decreases HR, Constricts Bronchi, and increases digestion?

Vagus nerve

What nerve controls the efferent part of the gag reflex?

Vagus

True or false: Sensorineural deafness is less common than conductive deafness

True

What is dysarthria?

Poor control of speech muscles Note: they still understand language

Damage to what nerve can cause dysarthria?

Hypoglossal

True or false: The dorsal root ganglion is a part of the CNS

False, it is part of the PNS

White matter tract vs column

Tract- bundle of axons with common destinaton Column- Several tracts

Where are the cell bodies of efferent neurons found?

Ventral horn

Where are the cell bodies of afferent neurons found?

Dorsal root ganglion

which CNs are parts of CNS?

1 AND 2

internerons - PNS or CNS?

CNS

What is epineurium

Fiberous sheath surrounding entire nerve

What is perineurium

Connective tissue wrapping around the fascicle of axons a peripheral nerve contains several fascicles

What is endoneurium

connective tissue surrounding each axon in a fascicle

Why is movement essential for nerve health?

movement promotes BF through the nerve and flow of the axoplasm through the axons axoplasm - transports chemicals b/w axons and cell bodies, regulates cell's fxn

What happens to axoplasm when we are stationary?

it thickens and becomes more resistant to flow

A alpha fibers are the ____ (speed) and send what info? What fiber is the slowest?

a alpha do muscle spindles and GTO, FASTEST (proprioception and motor?) C fibers that do pain are the slowest

somatic sensory special: visceral sensory special:

hearing, equilibrium and vision taste and smell (think internal)

if disc is impinging on spinal nerve, C6-C7 disc impinging on __ would be stated

where are spinal nerves formed? what space

intervertebral foramen

How would symptoms be different if you had a lesion on C6 spinal nerve root vs the median nerve?

with the root lesion, you would just have weakness bc other nerve roots contribute to the plexus the peripheral nerve lesion would cause complete loss to the muscle beign innervated each muscle limb receives its nerve supply from > 1 spinal nerve

damage to 1 spinal segment or root can/cannot completely paralyze any limb muscle

CANNOT

lumbar plexus carries efferent to muscles of carries afferent sensory from what regions

motor - anterior pelvis, anterior medial thigh afferent - skin of ant pelvis, medial and anterior thigh and medial lower leg

Lumbar plexus is nerve roots _ - __ Sacral is __ to __

L1-L4 L5-S4

sacral plexus efferent and afferent locations

efferent to posterior pelvis and posterior thigh and post lower leg and foot afferent to skin of same areas

polyneuropathy

distal, symmetric distribution glove and stocking, diabetes?

multiple mononeuropathy

multifocal random, asymmetric involvment of indiv. nn

Traumatic myelinopathy is mono/poly, is due to ___ and can have a ____ recovery an example would be

mononeuropathy repeated mechanical pressure that can occlude BF and damage myelin full recovery carpal tunnel

traumatic axonopathy is mono/poly, is when the ___ is damaged but the ___ is intact, meaning the nerve can ____ examples would be

mononeuropathy axon shwann cells/myelin regrow at 1mm/day crush injuries or closed fracture

Severance of a nerve has ___ prognosis

poor

polyneuropathy is ____ involvement of sensory, motor, and autonomic fibers and progresses from ___ to ____

symmetric distal to proximal (stocking and glove)

what is meant that polyneuropathy is "length dependent"

longer fibers are attacked first

first symptoms of polyneuropathy tend to be

sensory loss/dysfunction small fibers first - pain, temp, numbness, dysthesias

What is Guilain Barre Syndrome (acute inflammatory demyelinating polyradiculoneuropathy)

inflammatory demyelinating syndrome that typically occurs after viral infection causing more motor than sensory problems, distal to proximal can affect respiratory muscles - need ventilator good prognosis

PNS dysfinction muscle tone is CNS dysfunction muscle tone is

PNS - hypotonia CNS - hypertonia

Muscle atrophy is ___ with PNS dysfxn and ___ with CNS dysfxn

rapid for PNS slow for CNS

PNS dysfxn: NCV is DTRs are CNS dysfxn: NCV is DTRs are

PNS NCV is decreased DTRs are decreased/absent CNS NCV is normal DTRs are increased or normal