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Anatomy > CN I, II, III, IV, VI > Flashcards

CN I, II, III, IV, VI Flashcards

1
Q

CN I axon type

A

SSA

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2
Q

CN II axon type

A

SSA

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3
Q

CN III axon type

A

GSE/GVE

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4
Q

CN IV axon type

A

GSE

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5
Q

CN IV axon type

A

GSE

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6
Q

Weakness on one’s right side would indicate a lesion in what pathway? UMN or LMN?

A

Corticospinal tract, UMN

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7
Q

CNS and PNS origin/termination of CN I?

A

CNS: Olfactory bulb
PNS: Olfactory epithelium

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8
Q

CNS and PNS origin/termination of CN II?

A

CNS: Lateral geniculate nucleus (thalamus), superior colliculus, hypothalamus

PNS: Retinal ganglion cells

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9
Q

CNS and PNS origin/termination of CN III?

A

CNS: Occulomoter nucleus

PNS: all eye muscles except superior oblique m. and lateral rectus m.

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10
Q

CNS and PNS origin/termination of CN IV?

A

CNS: Trochlear nucleus

PNS: Superior oblique m.

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11
Q

CNS and PNS origin/termination of CN VI?

A

CNS: Abducens nucleus

PNS: Lateral rectus m.

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12
Q

Where is the olfactory bulb located? How is it distributed?

A

Nasal cavity, bilaterally.

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13
Q

What causes pain association with a noxious chemical smell?

A

CN V sensory endings in olfactory bulb - spinal trigeminal nucleus associated with pain.

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14
Q

Where is olfactory epithelium located? How is it distributed?

A

Roof of nasal cavity, bilateral

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15
Q

What type of neuron is associated with the olfactory receptor?

A

bipolar

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16
Q

Olfactory vesicles have cilia coated with mucus secreted by what structure?

A

Bowman’s glands

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17
Q

Axons from what receptors are among the thinnest and slowest?

A

Olfactory

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18
Q

Name for bundles of olfactory receptors? Through what structure does it pass?

A

Fila, cribiform plate of ethmoid bone

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19
Q

Olfactory bulb develops as an outgrowth of what structure?

A

Telencephalon

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20
Q

What CN doesn’t involve relay through thalamus to cortex?

A

CN I

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21
Q

Olfactory fibers comprise axons made from what types of cells?

A

Mitral and tufted

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22
Q

First order neurons in olfaction are located where? 2nd order?

A

Olfactory epithelium. Mitral cells.

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23
Q

What structure acclimates one to smell?

A

Anterior olfactory nucleus

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24
Q

What structure is thought to regulate sensitivity of olfactory bulb?

A

Anterior olfactory nucleus

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25
Q

Where do olfactory fibers cross the midline?

A

Anterior commissure

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26
Q

To where does the lateral olfactory stria project?

A

Pyriform area. Amygdala, uncus, insula.

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27
Q

To where does the medial olfactory stria project?

A

Subcallosal medial frontal lobe.

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28
Q

What structure is responsible for emotional response to smell?

A

Medial olfactory stria

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29
Q

To what structures is olfactory information sent?

A

Hypothalamus, hippocampus, orbital cortex, thalamus, amygdala

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30
Q

What area of the retina has the highest acuity?

A

fovea

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31
Q

What must happen with light for focus to occur?

A

Refraction

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32
Q

Structure whose role is adjusting focus for near/far objects

A

Lens

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33
Q

Most refraction occurs where?

A

Cornea

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34
Q

What structure affects brightness and quality of image?

A

Iris

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35
Q

What 2 muscles control the size of the pupil? Where are they located?

A

Pupillary sphincter, pupillary dilator. Iris.

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36
Q

Photoreceptors synapse on what types of cells? Subsequently, what are the roles of these cells?

A

1) Bipolar cells - project to second synapses

2) Horizontal cells - spread laterally and interconnect receptors

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37
Q

Where do bipolar cells terminate?

A

Ganglion and amacrine cells.

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38
Q

What’s contained within the outer segment of photoreceptor cells? What are the roles of their contents?

A

Rods - rhodopsin, black/white at night. low acuity

Cones - cone pigments. Color. High acuity

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39
Q

What’s contained within the inner segment of photoreceptor cells? What is the role of its contents?

A

Mitochondria to synthesize pigments for outer core

40
Q

Two regions of retina? Which pathway is ipsilateral, which is contralateral?

A

Temporal (lateral) - ipsilateral.

Nasal (medial) - contralateral

41
Q

Most fibers in the optic tract travel to what structure?

A

Lateral geniculate nucleus (LGN)

42
Q

Where is the primary visual cortex located?

A

Banks of calcarine sulcus in the occipital lobe.

43
Q

Retinotopic arrangement has how many layers?

A

6

44
Q

Outline the layers and roles in the retinotopic arrangement. From which eye does each layer get input?

A

Parvocellular layers (Color and form): 3-6

Magnocellular layers (movement and contrast): 1-2

From contralateral eye: 1, 4, 6

From ipsilateral eye: 2, 3, 5

45
Q

In LGN projections, what visual vields appear most superior in radiations? What about most inferior?

A

Superior in radiation: inferior visual field fibers.

Inferior in radiation: superior visual field fibers.

46
Q

An optic tract fiber could bypass LGN and end up at what structure?

A

Superior colliculus

47
Q

Define anopia/anopsia

A

Loss of one or more quadrants in a visual field

48
Q

Loss of half a visual field

A

Hemianopia

49
Q

Loss of 1/4 of a visual field

A

Quadrantanopia

50
Q

Similar visual field lost in each eye

A

Homonymous

51
Q

Two eyes have non-overlapping visual field loss

A

Heteronymous

52
Q

Damage anterior to chiasm affects ___________

A

ipsilateral eye - blind

53
Q

Damage at chiasm causes __________

A

heteronymous deficits

54
Q

Damage to optic tract causes ________

A

homonymous deficits

55
Q

The trochlea is a small notch on the orbital roof; what muscle wraps through this structure?

A

Superior oblique m.

56
Q

Extrinsic eye muscles are innervated by what CNs?

A

IV and VI

57
Q

What eye muscle elevates?

A

Superior rectus m.

58
Q

What eye muscle depresses?

A

Inferior rectus m.

59
Q

What eye muscle adducts?

A

Medial rectus m.

60
Q

What eye muscle is external rotation

A

Inferior oblique m.

61
Q

What eye muscle controls internal rotation?

A

Superior oblique m.

62
Q

What eye muscle abducts?

A

Lateral rectus m.

63
Q

In what brainstem region does CN III originate?

A

Rostral midbrain

64
Q

In what brainstem region does CN IV originate?

A

Caudal midbrain

65
Q

In what brainstem region does CN VI originate?

A

caudal pons

66
Q

Outline the process of constriction of pupils in response to light

A

1) Afferent limb takes stimulus from retinal ganglia to pretectal nuclei
2) Pretectal nucleus linked to EWN via posterior commissure
3) Preganglionic parasymptathetic fibers in CN III synapse in ciliary ganglion.
4) Postganglionic fibers in short ciliary nerves enter iris, supply sphincter of pupillae

67
Q

Why are lenses flat at rest?

A

Tension on capsule from suspensory ligament.

68
Q

Accommodation refers to

A

the near response

69
Q

Injury to what CN would result in affected eye being “down and out”

A

CN III

70
Q

Eye ipsilateral to lesion deviates in which direction?

A

Laterally

71
Q

What is Diplopia? What is a cause?

A

Double vision. CN III injury

72
Q

Define ptosis

A

Droopy eyelid

73
Q

Pupil on affected side is dilated

A

Mydriasis

74
Q

A CN III injury would cause what with respect to pupil and lens

A

Pupil would not constrict in response to light. Lens would not focus for near vision.

75
Q

Effect of CN IV lesion

A

Head tilts away, affected eye points up

76
Q

What muscle is innervated by VI. What’s this muscle’s action?

A

Ipsilateral lateral rectus m. Abducts eye

77
Q

What structures are medial to VI nucleus?

A

MLF and motor fibers of VII

78
Q

Site where VI fibers wrap around and turn to exit

A

Internal genu of CN VII

79
Q

Structure associated with CN VI nucleus action with internal genu

A

facial colliculus

80
Q

Define medial strabismus

A

affected eye is deviated medially

81
Q

The afferent and efferent limbs in the pupillary light reflex are associated with which CNs respectively?

A

II, III

82
Q

Through what structure does CN VI enter the orbit?

A

Superior orbital fissure

83
Q

Which CN tract is susceptible to increased intracranial pressure?

A

VI

84
Q

What is MLF? What does it do? How does it do this?

A

Medial longitudinal fasiculus. Allows coordination of head and eye movement by interconnecting III, IV, and V nuclei.

85
Q

What kind of neurons ascend in MLF? These neurons contain nuclei from what CNs?

A

Motor and internuclear. III, IV and V.

86
Q

VI nuclear damage causes what? What effect does this have on eye movement?

A

Medial strabismus and lateral gaze paralysis. Ipsilateral eye won’t abduct past midline; contralateral eye won’t adduct past midline.

87
Q

Paralysis of the eye due to damage between the nuclei

A

internuclear opthalmoplegia

88
Q

MLF damage removes excitatory input to what structure?

A

ipsilateral III nucleus

89
Q

If there’s an MLF injury, but both VI nuclei are intact, what movement would eyes be capable of?

A

Lateral

90
Q

Eyes moving as a pair is known as what kind of movement?

A

Conjugate movement

91
Q

Define scanning

A

eyes move from one visual target to another in high-speed movement known as saccades

92
Q

Define tracking

A

eyes follow area of interest across visual field.

93
Q

Define compensation

A

gaze held on object of interest during head movement, known as vestibulo-ocular reflex.

94
Q

Gaze centers are housed where?

A

RF

95
Q

What structure controls horizontal saccades?

A

Paramedian pontine reticular formation

96
Q

What structure controls upward saccades?

A

Midbrain, rostral interstitial nuclei of MLF

97
Q

What structure controls downward saccades?

A

In midbrain next to upward center

Anatomy (11 decks)

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