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Anatomy II Unit 1 > CNs > Flashcards

CNs Flashcards

1
Q

axon type, origin and termination of CN I

A

special sensory afferent; origin in olfactory epithelium; termination in olfactory bulb

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2
Q

dendrite of olfactory receptor ends in ____, from which 10-30 cilia spread over surface in a layer of mucus secreted by ____

A

olfactory vesicle; Bowman’s glands

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3
Q

axons from olfactory receptors collect into a series of bundles called ____; pass through holes in ____ of ethmoid bone

A

olfactory fila; cribriform plate

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4
Q

as the olfactory tract approaches the brain, it sends off 3 branches:

A

lateral olfactory stria to lateral (primary) olfactory area
intermediate olfactory stria- rudimentary in humans
medial olfactory stria to secondary olfactory area

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5
Q

lateral (primary) olfactory area is:

A

cortex over uncus, entorhinal area, limen insula, and amygdala

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6
Q

lateral (primary) olfactory area sends axons to ____ area which includes the uncus, entorhinal area, and limen insula

A

pyriform a

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7
Q

medial olfactory stria sends axons to:

A

subcallosal region of medial frontal lobe surface; emotional response to smell

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8
Q

olfactory bulb projections from the lateral olfactory stria

A
  • cortex near lateral olfactory tract aka piriform area
  • cortex covering amygdala aka periamygdaloid cortex
  • small part of parahippocampal gyrus
  • amygdala
  • entorhinal area
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9
Q

olfactory information sent to:

A

thalamus, hypothalamus, hippocampus, orbital cortex, amygdala

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10
Q

olfactory association cortex:

A

orbital surface of frontal lobe and anterior insula (near taste)

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11
Q

axon type, origin, and termination of CN II

A

special sensory afferent

origin: retinal ganglion cells
termination: lateral geniculate nucleus (in thalamus), superior colliculus, hypothalamus

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12
Q

____ and ___ focus image on the retina

A

cornea; lens

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13
Q

focus requires ____ of light

A

refraction

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14
Q

accounts for about a third of the eyes refractive power; has major role in adjusting focus for near/far objects

A

the lens

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15
Q

most refraction is in the _____

A

air-water interface at the corneal surface

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16
Q

affects brightness and quality of image focused on the retina

A

iris

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17
Q

highly specialized cells with different structural regions

A

rods and cones (photoreceptors)

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18
Q

outer segment contains visual ____

A

protein/pigment

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19
Q

damage anterior to chiasm only affects _____ eye

A

ipsilateral

20
Q

damage at chiasm causes _____ deficits

A

heteronymous

21
Q

damage to optic tract causes ____ deficits

A

homonymous

22
Q

CN III axon type, origin, termination

A

general somatic efferent from oculomotor nucleus to superior/inferior/medial rectus mm, inferior oblique m, and levator palpebrae superioris m.
general visceral efferent from EW nucleus to ciliary ganglion to sphincter pupillae m. (parasympathetics to the eye)

23
Q

CN IV axon type, origin, termination

A

general somatic efferent from trochlear nucleus to superior oblique m.

24
Q

CN VI axon type, origin, termination

A

general somatic efferent from abducens nucleus to lateral rectus m.

25
Q

oculomotor nucleus is in the _____

A

rostral midbrain

26
Q

trochlear nucleus is in the _____

A

caudal midbrain

27
Q

abducens nucleus is in the _____

A

floor of the 4th ventricle, caudal pons

28
Q

the near response (what happens to the eye during near vision)

A

ciliary muscle contracts, relaxing lens suspensory ligament and lens bulges of thickens; sphincter pupillae contracts, decreasing light coming through lens periphery (which is thinner)

29
Q

accommodation for the near response involves:

A

constriction of the pupil, changing shape of the lens, and medial convergence of the eyes

30
Q

all steps of accommodation for the near response is carried out by ____

A

CN III

31
Q

results of CN III injury

A
  • affected eye (ipsilateral to lesion) is “down and out”
  • pt will experience diplopia or double vision
  • cannot move eye medially (bc medial rectus is impaired)
  • pt will experience ptosis or a drooping upper eyelid
  • mydriasis- pupil on affected side is dilated
  • pupil does not constrict in response to light
  • lens cannot be focused for near vision
32
Q

CN IV innervates ____ m.

A

superior oblique

33
Q

results of CN IV injury

A
  • eye tilts up slightly (pt may tilt their head to the opposite side of the defective eye to accomodate)
  • pts report diplopia when going down stairs or reading
34
Q

CN VI innervates ____, which abducts the eye

A

ipsilateral lateral rectus m.

35
Q

CN VI has a long intracranial course, making it susceptible to increase ____ which usually results in _____

A

intracranial pressure; bilateral VI palsy

36
Q

CN VI injury results in:

A

medial stabismus (affected eye deviates medially)

37
Q

allows coordination of head and eye movement; interconnects CNs III, IV, and VI nuclei to allow this

A

medial longitudinal fasciculus (MLF)

38
Q

CN III, IV, and VI nuclei contain ____ and ____ that ascend in MLF

A

motor neurons; internuclear neurons

39
Q

CN VI nuclear damage causes ____ and _____

A

medial stabismus; lateral gaze paralysis

40
Q

what happens with lateral gaze to the ipsilateral side of the lesion when CN VI nucleus is damaged

A

ipsilateral eye cannot abduct past midposition and contralateral eye cannot adduct past midposition

41
Q

MLF injury results in:

A
  • internuclear ophthalmoplegia
  • removes excitatory input to ipsilateral CN III nucleus
  • eye ipsilateral to lesion fails to look past midposition during horizontal gaze
  • both VI nuclei intact so lateral movements of both eyes is intact
42
Q

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

A

scanning

43
Q

scanning gaze centers are in brainstem _____

A

reticular formation

44
Q

where are the horizontal saccades

A

paramedian pontine reticular formation (PPRF); each pulls eye to its own side

45
Q

where are the upward saccades

A

midbrain, rostral interstitial nuclei of the MLF (riMLF)

46
Q

where are the downward saccades

A

in midbrain next to upward center

47
Q

steps to voluntary saccade to the left

A
  1. projection from right frontal eye field activates left PPRF
  2. some PPRF neurons activate adjacent CN VI neurons (innervates left lateral rectus m)
  3. other PPRF neurons send heavily myelinated (fast) internuclear fibers in MLF to activate CN III, serving the right medial rectus
  4. simultaneous contraction of the respective rectus muscles yields a saccade to the left

Anatomy II Unit 1 (11 decks)

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