Lecture 7 - Cranial Nerves (part 1) Flashcards

1
Q

How many paired cranial nerves are there?

A

12

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2
Q

How are the cranial nerves numbered?

A

from rostral to caudal

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3
Q

What do cranial nerves carry both of?

A

sensory and motor information

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4
Q

What are the 6 modalities of cranial nerves?

A

sensory: somatic, special, visceral
motor: somatic, branchial, visceral

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5
Q

What are examples of somatic sensory modalities?

A

touch (pain, temperature, vibration)

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6
Q

What are examples of special sensory modalities?

A

vision, hearing, taste, smell, balance

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7
Q

What are examples of visceral sensory modalities?

A

organs (pain)

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8
Q

What are examples of somatic motor modalities?

A

skeletal muscle derived from somites

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9
Q

What are examples of branchial motor modalities?

A

skeletal muscle derived from pharyngeal arches

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10
Q

What are examples of visceral motor modalities?

A

parasympathetic only (craniosacral outflow)

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11
Q

How do most cranial nerves enter/exit?

A

through the brainstem

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12
Q

Which cranial nerves do not pass through brainstem

A

I, II, XI

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13
Q

What are the 12 cranial nerves?

A

olfactory
optic
oculomotor
trochlear
trigeminal
abducens
facial
vestibulocochlear
glossopharyngeal
vagus
spinal accessory
hypoglossal

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14
Q

Where are the bipolar neurons found in the olfactory nerve?

A

olfactory epithelium (roof of nasal cavity)

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15
Q

What do peripheral processes have?

A

cilia

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16
Q

What are cilia in the nose stimulated by?

A

odorous substances

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17
Q

What foramina does the olfactory nerve travel through?

A

the cribriform plate

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18
Q

Where do bipolar neurons in the olfactory epithelium synapse in?

A

the olfactory bulbs

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19
Q

After synapsing in the olfactory bulbs, where do bipolar neurons go?

A

in the cerebral cortex

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20
Q

What type of modality is the olfactory nerve?

A

special sensory

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21
Q

Where is the olfactory nerve located?

A

inferior aspect of frontal lobes

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22
Q

What is found in the upper nasal cavity?

A

dissolved odorants

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23
Q

Where does the optic nerve transmit visual information?

A

from retina into the skull

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24
Q

Which foramen does the optic nerve pass through?

A

the optic canal

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25
Q

Where is the location of the optic nerve?

A

exits orbit and contributes to optic chiasm anterior to pituitary gland

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26
Q

What is the pathway of neurons of the optic nerve?

A

Some neurons cross the midline at the optic chiasm -> continue
as optic tracts with information from left visual field on right (& vice versa)
synapse in thalamus (lateral geniculate nucleus) -> then carried to cortex

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27
Q

Where does the optic nerve synapse before carried to cortex?

A

in the thalamus

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28
Q

What are the 3 sections of the brainstem?

A

midbrain, pons, medulla

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29
Q

What does the vestibulocochlear nerve transmit to the brain?

A

balance and auditory information

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30
Q

What is found in the inner ear and cochlea?

A

specialized hair cells

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31
Q

The vestibular and cochlear parts of the ear merge to form the…

A

vestibulocochlear nerve

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32
Q

Where does the vestibulochoclear nerve synapse?

A

in brainstem and thalamus

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33
Q

What is the modality of the vestibulocochlear nerve?

A

special sensory (balance and hearing)

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34
Q

What foramen does the vestibulocochlear nerve pass through?

A

internal acoustic meatus

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35
Q

Where does the vestibulocochlear nerve enter from?

A

enters brainstem between pons and medulla

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36
Q

What type of modality is the oculomotor nerve?

A

somatic motor and visceral motor

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37
Q

Where does the oculomotor nerve exit?

A

anterior side of midbrain

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38
Q

What is the modality of the trochlear nerve?

A

somatic motor

39
Q

Where does the trochlear nerve exit?

A

posterior side of midbrain

40
Q

What is the modality of the abducens nerve?

A

somatic motor

41
Q

Where does the abducens nerve enter from?

A

between the pons and medulla

42
Q

What do all three nerves (oculomotor, trochlear and abducens) pass through?

A

superior orbital fissure

43
Q

What direction does each apex of the orbit osteology point in?

A

posteromedial

44
Q

What kind of orientation do the apex cavity create in an orbit osteology?

A

oblique orientation

45
Q

What are the 2 kinds of axes of the eye?

A

orbital and optical

46
Q

How many bones contribute to each orbit?

A

7

47
Q

Where is the optic canal located in the orbit?

A

at the apex

48
Q

What are the 7 bones of the orbit osteology?

A
  1. frontal
  2. sphenoid
  3. ethmoid
  4. palatine
  5. lacrimal
  6. maxilla
  7. zygomatic
49
Q

What are the 3 fossae of the orbit osteology?

A

superior orbital fissure
optic canal
inferior orbital fissure

50
Q

How many extraocular muscles are there?

A

7

51
Q

How many extraocular muscles attach to the eyeball?

A

6

52
Q

What are the 3 rotational axes of the eye?

A

horizontal, vertical and anteroposterior

53
Q

What are the names of the 7 extraocular muscles?

A
  1. medial rectus
  2. inferior rectus
  3. superior oblique
  4. inferior oblique
  5. superior rectus
  6. lateral rectus
  7. levator palpeerde superioris
54
Q

What is the attachment site for the extraocular muscles?

A

common tendinous ring

55
Q

What is the function of the levator palpebrae superioris muscle?

A

elevates the superior eyelid

56
Q

Where does the levator palpebrae superioris attach to?

A

sphenoid bone

57
Q

Which part of the eyeball do the rectus muscles attach to?

A

anterior part

58
Q

Which part of the eyeball do the oblique muscles attach to?

A

posterior part

59
Q

Where do the medial and lateral rectus attach?

A

common tendinous ring and anterior sclera on the medial and lateral sides

60
Q

Which axis do the medial and lateral rectus contribute to?

A

vertical axis

61
Q

What movement is produced by the medial rectus?

A

adduction

62
Q

What movement is produced by the lateral rectus?

A

abduction

63
Q

Where do the superior and inferior rectus muscles attach?

A

common tendinous ring and to the anterior sclera on the superior and inferior aspects

64
Q

Which primary axis do the superior and inferior rectus muscles contribute to?

A

horizontal axis

65
Q

What secondary axis do the superior and inferior rectus muscles contribute to?

A

A-P axis

66
Q

What tertiary axis do the superior and inferior rectus muscles contribute to?

A

vertical axis

67
Q

What actions does the superior rectus muscle perform?

A

elevation, intorsion, adduction

68
Q

What actions does the inferior rectus muscle perform?

A

depression, extortion, adduction

69
Q

Why do the superior and inferior rectus muscles perform multi axial actions?

A

because of the lack of alignment between the optical and orbital axes

70
Q

Where does the superior oblique muscle attach to?

A

the sphenoid & passes through a fibrous sling (trochlea)

71
Q

Where does the inferior oblique muscle attach to?

A

the maxilla on the anteromedial floor of the orbit

72
Q

What is the primary, secondary and tertiary axes that the superior and inferior oblique muscles contribute to?

A
  • A-P axis
  • horizontal axis
  • vertical axis
73
Q

What actions does the superior oblique muscle perform?

A

intorsion, depression, abduction

74
Q

What actions does the inferior oblique muscle perform?

A

extorsion, elevation, abduction

75
Q

How can we test extraocular muscles?

A

H-test

76
Q

what do we do to the optical axis with the line of pull for the SR/IR and SO/IO muscles?

A

we align them

77
Q

How many degrees of abduction are required to align the optical axis with the line of pull for the superior and inferior rectus muscles?

A

23 degrees

78
Q

Which muscle produces 23 degrees of abduction?

A

the lateral rectus

79
Q

How many degrees of adduction are required to align the optical axis with the line of pull for the superior and inferior oblique muscles?

A

51 degrees

80
Q

Which muscle produces 51 degrees of adduction?

A

medial rectus muscle

81
Q

The oculomotor nerve provides somatic motor innervation to which muscles?

A

levator palpebrae superioris, superior
rectus, inferior rectus, medial rectus, + inferior oblique
muscles

82
Q

The oculomotor nerve provides visceral motor innervation to which muscles?

A

sphincter muscles and ciliary muscles

83
Q

Which muscle does the trochlear nerve provide innervation to?

A

superior oblique muscle

84
Q

Which muscle does the abducens nerve provide innervation to?

A

lateral rectus muscle

85
Q

CN III and VI pass ___ tendinous ring; CN IV passes ___.

A

through, above

86
Q

Where does one of the eyes move to in oculomotor nerve palsy?

A

bottom corner

87
Q

Where does one of the eyes move to in trochlear nerve palsy?

A

top corner

88
Q

Where does one of the eyes move to in abducens nerve palsy?

A

towards the centre

89
Q

Where does parasympathetic innervation of the eye come from?

A

oculomotor nerve

90
Q

Where does the oculomotor nerve synapse in?

A

ciliary ganglion

91
Q

What do the postganglionic oculomotor neurons form?

A

short ciliary nerves

92
Q

Contraction of ciliary muscle ___ its internal diameter + lens becomes more rounded

A

decreases

93
Q

Contraction of sphincter pupillae ____ pupil

A

constricts

94
Q

Where does sympathetic innervation of dilator pupillae come from?

A

T1-T4 lateral horns