LEC50: Cranial Nerves I Flashcards

1
Q

2 types of bone formation of human skull

A

1) bottom: cartilagenous endochondral
2) face: membranous

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2
Q

which area of the skull is evolutionarily older?

A

bottom of skull, the chondrocranial base

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3
Q

which area of skull is malleable? which is not? why?

A

face/vault is malleable

bottom of skull isn’t malleable b/c cranial foramina there, where nerves exit / vascular supply enters

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4
Q

what is fontanella?

A

soft spot on top of baby’s skull

newborn’s face/vault very malleable; skull base is not malleable

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5
Q

what is hydrocephalus

A

abnormal accumulation of CSF in brain; increases intracranial pressure inside skull, progressively enlarges head

most common in infants

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6
Q

what view of skull is this

A

exocranial view of skull

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7
Q

what view of what structure is this? what does it enable visualization of?

A

endocranial view of skull base

see important foramina

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8
Q

list cranial nerves, by number and name

A

I: olfactory

II: optic

III: oculomotor

IV: trochlear

V: trieminal

VI: abducens

VII: facial

VIII: vestibulo-cochlear

IX: glossopharyngeal

X: vagus

XI: spinal accessory

XII: hypoglossal

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9
Q

“general” nerve fibers defn, types

A

fibers that can be found anywhere in the body

4 types:

GSE, general somatic efferent

GVE, general visceral efferent

GSA, general somatic afferent

GVA, general visceral afferent

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10
Q

meaning of “general” re: spinal nerves

A

found anywhere in the body

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11
Q

meaning of “somatic/visceral” re: spinal nerves

A

visceral: gut innervated
somatic: not gut innervated

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12
Q

meaning of “efferent/afferent” re: spinal nerves

A

efferent: motor
afferent: sensory

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13
Q

“special” nerve fibers of the head/neck (3)

A

1) SVE, special visceral efferent
2) SVA, special visceral afferent
3) SSA, special somatic afferent

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14
Q

what are SVE fibers? why visceral?

A

MOTOR fibers relating to muscles derived from the branchial arches

VISCERAL designation THOUGH GO TO SKELETAL MUSCLE! because branchial arches at first were part of aero-digestive system

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15
Q

what are SVA fibers?

A

fibers relating to taste, smell

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16
Q

what are SSA fibers?

A

non-gut related special sense fibers

vision, balance, hearing

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17
Q

how many types of fibers can a cranial nerve have?

A

up to 7 because 4 general and 3 special types of fibers

however, max number found is 5!

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18
Q

3 groupings of cranial nerves

A

1) special sensory nerves
2) myotomal nerves
3) branchiomeric nerves

*3, 4, 5 system of subdividing cranial nerves*

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19
Q

special sensory nerves are?

A

*3*

I: olfactory

II: optic

VIII: vestibulo-cochlear

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20
Q

myotomal nerves are? general fxn?

A

III: oculomotor

IV: trochlear

VI: abducens

XII: hypoglossal

innervate skeletal muscle derived from myotomes

*4*

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21
Q

branchiomeric nerves are? general fxn?

A

V: trigeminal

VII: facial

IX: glossopharyngeal

X: vagus

XI: spinal accessory

nerves related to branchial arches

*5*

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22
Q

fiber type, CNI: olfactory nerve

A

SVA

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23
Q

fiber type, CNII: optic nerve

A

SSA

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24
Q

fiber type, CNVIII: vestibulo-cochlear n

A

SSA

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25
Q

what is misnomer about CNI: olfactory n / why?

A

not actually a nerve; it’s a brain tract

was called nerve historically, so misnomer stuck

nerve must either: 1) if motor, go from motor nucleus > muscle or 2) if sensory, have a primary sensory neuron in a ganglia - CNI has neither

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26
Q

structure of CNI: olfactory n?

A

olfactory tract, bulb, nerve

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27
Q

important structures of this image?

A

olfactory bulb, nerve, tract

specialized sensory epithelium

communicates w/ mitral tufted cell and nerve

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28
Q

hyperosmia

A

heightened sense of smell

re: CNI, olfactory nerve

cocaine users have hyperosmia

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29
Q

cacosmia

A

condition where always perceive foul odors, even if none present

30
Q

what’s unique about CNII: optic nerve structure?

A

is an optic tract/brain tract, like olfactory nerve- it’s NOT A NERVE

31
Q

where does CNII: optic nerve run?

A

from visual cortex > through optic foramena

32
Q

where is CNI: olfactory n located?

A

small fibers in nose septum and undearneath in turbiantes lying on superior nasal concha

pass through cribiform plate of ethmoid bone

33
Q

what foramena is this? what goes through it?

A

optic foramena

CNII, optic n

34
Q

how does 1-eyed blindness present in brain?

A

atrophy of optic n

35
Q

is brain sensitive to pain?

A

no, dura surrounding brain is

36
Q

astrocytoma?

A

tumor in brain - swelling in brain tissue

37
Q

where do you find optic astrocytoma?

A

near chiasm

38
Q

function of CNVIII

A

CNVIII: vestibulocochlear nerve

hearing, balance

39
Q

where does CNVIII: vestibulo-cochlear nerve exit skull base

A

internal acoustic meatus

40
Q

fiber type of nerves i nmyotomal nerve group?

A

all are GSE EXCEPT CNIII, oculomoter, also GVE parasympathetic fibers

41
Q

nerves of oculomotor system, function

A

CNIII, oculomotor; IV, trochlear; VI, abducens

move the eyeball

42
Q

which cranial nerves are innervating this structure

A

III, IV, VI

43
Q

what is this condition? what cranial nerve’s affected?

A

congenital bilateral external rectus palsy

CNVI: abducens palsy

44
Q

what is major nerve for tongue innervation?

A

hypoglossal n

45
Q

what nerve fiber type do all branchiomeric group nerves have?

A

SVE, because derived from branchial arches

46
Q

nerve fiber types for CNV, trigeminal n

A

SVE, GSA

47
Q

nerve fiber types for CNVII, facial n

A

SVE: branchial mm - 2nd arch

GSA: general somatic sensation

GVE: parasympathetic fibers

SVA: taste, anterior 2/3 tongue

48
Q

nerve fiber types for CNIX, glossopharyngeal n

A

SVE: branchial mm, 3rd arch

GVA: general visceral sensation

GVE: parasympathetic fibers

GSA: general somatic sensation

SVA: taste, posterior 1/3 of tongue

49
Q

nerve fiber types for CNX, vagus

A

SVE: branchial mm, 4th arch

GSA: general somatic sensation

GVE: parasympathetic fibers

GSA: general somatic sensation

SVA: taste, epiglottis

50
Q

nerve fiber types, CNXI, spinal accessory n

A

SVE: branchial archs 5-6

GSE: spinal part

51
Q

what innervates mastication muscles?

A

SVE of CNV, trigeminal n

52
Q

CNV, trigeminal n, divisions?

A

V1: opthalmic

V2: maxillary

V3: mandibular

53
Q

name nerve, divisions

A

trigeminal n

green: V1, opthalmic
blue: V2, maxillary
salmon: V3, mandibular

54
Q

sensory field of CNV, trigeminal n, both re: divisions and overall

A
55
Q

cause and presentation of trigeminal neuralgia? possible cause?

A

compression of 1 division of trigeminal n

unrelenting, intense pain

possible cause- artery compressing nerve/branches

56
Q

functions of CNVII, facial n?

A

facial expression muscles- smile, frown, close eyelids

carries taste from anterior 2/3 of tongue

57
Q

where does CNVII, facial n, pass through?

A

through temporal bone’s internal auditory canal

through parotid gland > facial muscles

58
Q

what is this example of?

A

bell’s palsy aka facial palsy

CNVII, facial n, insulted

59
Q

nerve fibers of glossopharyngeal n, CNIX?

A

5! most found in any CN (+ vagus also 5)

SVA: branchial, 3rd arch

GVA

GVE: parasympathetic

GSA

SVA: taste, posterior 1/3 tongue

60
Q

key nerve for gag reflex?

A

CNIX, glossopharyngeal nerve

61
Q

what comes out of jugular foramen?

A

CNIX- glossopharyngeal, CNX- vagus

62
Q

what structure carries taste?

A

epiglottis

63
Q

nerve fibers/their fxns for CNX, vagus?

A

SVE- branchial, 4th arch

GVA

GVE

GSA

SVA- taste, epiglottis

64
Q

where are primary sensory neurons of cranial nerves located?

A

in ganglia OUTSIDE the CNS - like DRGs of spinal nerves

65
Q

which cranial nerves do not have ganglia?

A

CNI, CNII because not real nerves

66
Q

sensory ganglia of the cranial nerves?

A

CNV: trigeminal (semilunar) ganglion - LARGEST, MOST IMPORTANT

CNVII: geniculate ganglion

CNVIII: vestibular ganglion; cochlearn (spiral) ganglion

CNIX: superior and inferior glosspoharyngeal ganglia

CNX: superior (jugular) and ifnerior (nodose) ganglia

67
Q

what is a shockingly sensitive part of the body?

A

auricle

68
Q

what provides auricular sensation and to where?

A

CNV- auriculotemporal branch

CNVII- small area, posterior canal wall

CNIX- medial, inner part of tympanic membrane (tympanic n)

CNX- most of ear canal, pt of outer surface of tympanic membrane (auricular br; arnold’s s n)

Greater auricular n (C2, C3)

Lesser occipital n (C2)

69
Q

nerve fiber types of parts of CNXI, spinal accessory n

A

SVE- cranial root

GSE- spinal part

70
Q

what does spinal part of CNXI innervate?

A

trapezius m- adduct arm, elevate shoulder

sternocleidomastoid m- tilts, rotates head

71
Q

what happens to cranial part of CNXI, spinal accessory n?

A

joins CNX, vagus n

72
Q

what is spinal accessory nerve’s route?

A

UNIQUE b/c both enters and exits skull:

arises from C1-C5 ventral horn cells; forms trunk

ascends into skull thru foramen magnum

then exits skull thru jugular foramen, with CNX

runs backwards, descends obliquely behidn digastric and stylohyoid muscles to upper pt of sternocleidomastoid; courses obliquely across neck, to trapezius m