Cranial Nerves Flashcards

1
Q

Cranial nerves are form what part of the NS?

A

peripheral

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2
Q

What are the 12 cranial nerves? pneumonic

A

OOOTTAFVGVAH

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3
Q

What is cranial nerve I?

A

olfactory

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4
Q

What is cranial nerve II?

A

optic

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5
Q

What is cranial nerve III?

A

oculomotor

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6
Q

What is cranial nerve IV?

A

trochlear

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7
Q

What is cranial nerve V?

A

trigeminal

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8
Q

What is cranial nerve VII?

A

facial

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9
Q

What is cranial nerve VIII?

A

vestibulocochlear

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10
Q

What is cranial nerve IX?

A

glossopharyngeal

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11
Q

What is cranial nerve X?

A

vagus

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12
Q

What is cranial nerve XI?

A

accessory

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13
Q

What is cranial nerve XII?

A

hypoglossal

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14
Q

What are cranial nerves I & II, and where are they located?

A

olfactory and optic
in cerebrum

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15
Q

What are cranial nerves III & IV, and where are they located?

A

oculomotor and trochlear
in midbrain

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16
Q

What is cranial nerve V and where is it located?

A

trigeminal
in pons

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17
Q

What are cranial nerves VI, VII & VIII, and where are they located?

A

abducens, facial and vestibulocochlear

pontomedullary junction

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18
Q

What are cranial nerves IX, X, XI, XII and where are they located?

A

glossopharyngeal, vagus, accessory, hypoglossal,
medulla

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19
Q

What are the 3 sensory-only cranial nerves?

A

olfactory (I)
optic (II)
vestibulocochlear (VIII)

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20
Q

What are the 5 motor-only cranial nerves?

A

oculomotor (III)
trochlear (IV)
abducens (VI)
accessory (XI)
hypoglossal (XII)

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21
Q

What cranial nerves are both sensory and motor?

A

trigeminal (V/5)
facial (VII/7)
glossopharyngeal (IX/9)
vagus (X/10)

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22
Q

olfactory epithelium located where?

A

roof of nose

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23
Q

What type of neuron is the olfactory nerve (I)? What sets it apart from other CNS?

A

bipolar, axon makes it the shortest CN

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24
Q

Where is the olfactory bulb?

A

bulb over cribriform plate of ethmoid bone

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25
Q

How is smell transmitted to the brain?

A

olfactory tract takes smell to olfactory cortex

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26
Q

What are the different problems relating to smell?

A

anosmia
dysosmia
hyposmia
hyperosmia
phantosmia

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27
Q

What is anosmia?

A

loss of smell

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28
Q

What is dysosmia?

A

distorted sense of smell

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29
Q

What is hyposmia?

A

reduced ability to smell

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30
Q

What is hyperosmia?

A

increased ability to smell

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31
Q

What is phantosmia?

A

olfactory hallucinations

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32
Q

What drug classes can cause smell disorders/chemosensory effects?

A

topical decongestants
antibiotics
antihypertensives
antihistamines
antilipidemics

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33
Q

What are examples of decongestants that have a chemosensory effect?

A

decongestants containing zinc

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34
Q

What are examples of antibiotics that have a chemosensory effect?

A

amoxicillin
azithromycin
ciprofloxacin

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35
Q

What are examples of antihypertensives that have a chemosensory effect?

A

amlodipine
diltiazem
enalapril

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36
Q

What is an example of an antihistamine that has a chemosensory effect?

A

fluticasone

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37
Q

What is optic neuropathy?

A

damage to the optic nerve

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38
Q

What drugs can induce optic neuropathy?

A

ethambutol
amiodarone
vigabatrin

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39
Q

What is ethambutol optic neuropathy dependent on?

A

dose and duration

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40
Q

What dose and duration does optic neuropathy occur with ethambutol occur?

A

around 6% of px at a daily dose of 25mg/kg/day within 3-6 months of starting

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41
Q

How does amiodarone cause neuropathy?

A

irreversible demyelination

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42
Q

How do you monitor for neuropathy with ethambutol?

A

screen every weeks when dose >15mg/kg, every 3-6 mths for lower doses

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43
Q

How often is optic neuropathy for vigabatrin monitored for?

A

screening prior to starting treatment, then every 6 months, then 3 yrs and annually

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44
Q

What is the cause of vigabatrin-induced optic neuropathy?

A

idiosyncratic - nasal visual field loss

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45
Q

What is maculopathy?

A

damage to retina so px cannot focus on one thing but still has peripheral vision

46
Q

What drugs can cause maculopathy?

A

chloroquine, hydroxychloroquine
thioridazine
canthaxanthin
tamoxifen, nicotinic acid

47
Q

How does thioridazine cause maculopathy?

A

deposits drug in retinal pigment epithelium RPE
dose exceeds >800mg/day for a few weeks

48
Q

How do chloroquine and hydroxychloroquine cause maculopathy?

A

deposit drug in retinal pigment epithelium RPE
occurs in 7.5% of pts if used for >5 yrs

49
Q

How does canthaxanthin cause maculopathy?

A

deposits of tiny crystals, and foveolar cyst formation (duration dependent)

50
Q

How do tamoxifen and nicotinic acid cause maculopathy?

A

deposits of tiny crystals & foveolar cyst formation, (dose dependent)

51
Q

What is the function of the optic nerve?

A

vision:
- visual acuity
- colour
- contrast
- visual field

52
Q

Pneumonic for remembering innervation of extraocular muscles

A

LR6SO4
lateral rectus innervated by CN 6, abducens

superior oblique innervated by CN 4, trochlear

all rest innervated by CN 3, oculomotor

53
Q

What muscles are involved in eye movement?

A

4 recti muscles:
- superior, inferior, medial and lateral

2 obliques:
- superior and inferior oblique

levator palpebral superioris

54
Q

Which eye movement muscles does the oculomotor nerve (3) innervate?

A

superior, inferior and medial rectus
inferior oblique
levator palpebral superioris
(up down and inwards)

55
Q

Which eye movement muscle does the abducent nerve (6) innervate?

A

lateral rectus (move eye to outer side)

56
Q

Which eye movement muscles does the trochlear nerve (4) innervate?

A

superior oblique
in and down

57
Q

What should you remember in terms of where the eye muscles move the eye?

A

recti muscles are predictable and move according to their name
(sup up and inf down)

oblique muscles do the opposite - O for opposite

58
Q

Where do each rectus muscle move the eye?

A

lateral moves to lateral side out
medial moves medially in to nose
superior moves eye up and out
inferior moves eye down and out

59
Q

Where do the oblique muscles move the eye?

A

superior oblique moves eye down and in
inferior oblique moves eye up and in

60
Q

Based on the nerve that innervates the MR, SR, IR, IO, LPS: what type of innervation supplies these muscles?

A

motor

61
Q

What branch of the nervous system supplies the sphincter pupillae and ciliary muscle?

A

the parasympathetic

62
Q

What can damage to the oculomotor nerve (3) result in?

A

right third nerve palsy

63
Q

What are signs of right nerve palsy?

A

ptosis (drooping of upper lid)
mydriasis (pupil dilation)
cycloplegia (paralysis of eye)
normal abduction
limited elevation and depression

64
Q

What does damage of the trochlear nerve result in?

A

right fourth nerve palsy

65
Q

Based on what the trochlear nerve innervates, what are the signs of 4th right nerve palsy?

A

innervates superior oblique muscle which moves eye down and in

66
Q

What affects the trochlear nerve and why?

A

raised intracranial pressure ICP due to it being the only nerve to come out of dorsal side of brainstem, and its long course

67
Q

What can damage to the abducent nerve (VI) result in?

A

right 6th nerve palsy (improper innervation of lateral rectus muscle)

one eye facing closer into nose

68
Q

What can affect the abducent nerve and why?

A

longest nerves, so can be compressed by downward herniation due to raised ICP

69
Q

What drugs can cause myopathy of the extraocular muscle?
(antitumour therapies targeting immune checkpoints)

A

tremelimumab
durvalumab

70
Q

What are the symptoms of drug-induced myopathy?

A

diplopia (double vision)
ptosis
fatigue
weakness

71
Q

How do you examine the signs of myopathy of extraocular muscles?

A

electromyography (EMG) and muscle biopsy
would see multiple muscle weakness to varying extent

72
Q

How do you treat drug-induced myopathy?

A

withdraw drug and oral steroid therapy

73
Q

What are the 3 divisions of the trigeminal nerve?

A

ophthalmic
maxillary
mandibular

74
Q

What is the ophthalmic division of the trigeminal nerve?

A

sensory: including dura mater and forehead

75
Q

What is the maxillary division of the trigeminal nerve?

A

sensory: lower lid, cheek and maxillary sinus

76
Q

What is the mandibular division of the trigeminal nerve?

A

mix of sensory and motor:
- sensory: lower jaw, angle and temple
- motor: muscles of mastication

77
Q

What is trigeminal neuralgia?

A

chronic pain disorder characterised by sudden unilateral severe facial pain

78
Q

What are the 2 types of trigeminal neuralgia?

A

classic
atypical

79
Q

What is classic trigeminal neuralgia?

A

intermittent sudden burning/shock of pain lasting from a few seconds to 2 mins per episode

80
Q

What is atypical trigeminal neuralgia?

A

constant aching, burning, stabbing that stays for weeks and months

81
Q

What parts innervated by the facial nerve are sensory?

A

anterior 2/3 of tongue
external ear

82
Q

What parts innervated by the facial nerve are motor?

A

muscles of facial expression
stapedius muscle
posterior belly digastric
stylohyoid

83
Q

What parts of the facial nerve are innervated by parasympathetic input?

A

nasal, lacrimal glands
sublingual
submandibular

84
Q

What is bells palsy?

A

Inflammation or viral infection of the facial nerve that causes one sided weakness or the entire face

85
Q

What are some signs of bells palsy?

A

lower motor neuron lesion of facial nerve
ipsilateral facial muscle weakness (same side)
drooping of mouth
loss of forehead wrinkle
unable to close eyelids
loss of taste

86
Q

What are the functions of the branches of the vestibulocochlear nerve (branches are in the name)?

A

vestibular - balance
cochlear - hearing

87
Q

What can be used to diagnose deafness due to CN 8?

A

tuning fork tests (Weber’s and Rinne’s)

88
Q

What is a cerebellopontine angle tumor and what CNs does it affect?

A

acoustic neuroma affecting 7,8 and later 10,11

89
Q

What is drug-induced ototoxicity?

A

irreversible destruction of outer hair cells in organ of Corti, at cochlea and type I hair cells in vestibular apparatus

90
Q

What drug class can cause ototoxicity?

A

aminoglycosides (dose and duration dependent)

91
Q

What aminoglycosides are vestibulotoxic?

A

streptomycin and gentamicin

92
Q

What aminoglycosides are cochleotoxic?

A

neomycin and kanamycin

93
Q

Which of the aminoglycosides are safer (in terms of ototoxicity)?

A

amikacin and tobramycin

94
Q

What are signs of ototoxicty?

A

hearing loss
tinnitus
disequilibrium
dizziness and vertigo

95
Q

How can ototoxicity be screened for?

A

audiograms
serum drug levels
renal functions

96
Q

How long does it take drug-ototoxicity to resolve?

A

6 months

97
Q

What parts innervated by the glossopharyngeal nerve (IX) are sensory?

A

posterior 1/3 of tongue (remember anterior 2/3 is facial, VI)
palate
oropharynx
middle ear

98
Q

What parts innervated by the glossopharyngeal nerve (IX) are motor?

A

stylopharyngeus

99
Q

What parts innervated by the glossopharyngeal nerve (IX) are parasympathetic?

A

parotid gland

100
Q

What parts innervated by the vagus nerve (IX) are sensory?

A

pharynx
larynx
external ear
dura mater
aortic body chemoreceptors
aortic arc baroreceptors

101
Q

What parts innervated by the vagus nerve (IX) are motor?

A

palatoglossus
palate
pharynx
larynx

102
Q

What parts innervated by the vagus nerve (IX) are parasympathetic?

A

heart
bronchi
GI tract

103
Q

What 2 roots does the accessory nerve arise from?

A

nucleus ambiguous and spinal C1-5

104
Q

What muscles does the accessory nerve innervate?

A

sternocleidomastoid
trapezius

105
Q

How do you test the accessory nerve function?

A

ask patient to raise shoulder or
turn face against resistance applied by hand of examiner

106
Q

What is the function of the hypoglossal nerve (12)?

A

facilitating tongue movement

107
Q

What muscles does the hypoglossal nerve innervate?

A

intrinsic muscles of tongue:
hypoglossus
genioglossus
styloglossus

108
Q

How do you test hypoglossal nerve function?

A

protrude tongue straight and move from side to side

109
Q

How does the tongue behave with an upper motor neuron lesion in the hypoglossal nerve?

A

tongue is spastic, protrusion away

110
Q

How does the tongue behave with an lower motor neuron lesion in the hypoglossal nerve?

A

tongue shows wasting and fasciculations