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Neuro Final > Visual System > Flashcards

Visual System Flashcards

1
Q

what is the superior colliculus a part of? what is it importnat for?

A

part of the tectum

-important for orienting eyes and head to not only visual stimuli but also auditory and somatosensory stimuli

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2
Q

where is the accessory optic nuclei?

A

in the midbrain tegmentum

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3
Q

what central projections of RGCs (retinal ganglion cells) in the optic nerve are in the midbran, hypothalamus, and thalamus

A

midbrain: pretectal olivary nucleus, superior colliculus (tectum), accessory optic nuclei
hypothalamus: suprachaismitc nucleus
thalamus; lateral geniculate nucleus

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4
Q

which fibers cross and which stay straight

A

the nasal retinal fibers crossed to the opposite brain

temporal fibers continue straight

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5
Q

the chiasm carries _____ retinal fibers from each eye, representing the _____ field of each eye

A

chiasm carries nasal retinal fibers form each eye, thereby representing the temporal field of each eye

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6
Q

the tract carries ____ fibers from the _____ retina, and the crossed _____ fibers from the contralateral retina

A

the tract carries the temporal fibers from the ipsi retina (ipsi nasal field) and the crossed nasal fibers from the contralateral retina (contra temp field)

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7
Q

what are the 6 layers of the LGN

A

inner 2 layers called magnocellular layer
outer 4 layers are parvocellular

1, 4, 6 get info from contralateral retina (nasal)
2, 3, 5 get info from ipsi (temporal retina)

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8
Q

what is meyer’s loop

A

some raidations travel inf in the temporal lobe

-these inf radiations are carrying the same field info that was carried int he inf retina which is for the sup field

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9
Q

what is the rule of L’s (wehre do the lower retina fibers go)

A

lower retinal fibers, to the lateral LGN, into Meyer’s Loop, to synapse on the Lingual gyrus

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10
Q

where does inf field info go

A

superior retina
superior radiations (parietal lobe)
superior bank of occipital cortex (cuneus)

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11
Q

what separates the nasal from temporal retina

A

`the fovea

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12
Q

where do distal arcuates come from

where do proximal arcutes come from

A

distal: come from peripheral RGCs
proximal: RGCs closwer to optic disc

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13
Q

what kind of fibers are papillomacularbundles and where do they insert

A

nasal retinal fibers inserting into the temporal neuro-retinal rim
-go from the fovea (central) to ONH

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14
Q

what kind of retinal fibers are arcuates and wehre do they insert

A

temporal retinal fibers that arched over the papillomacular bundle to insert into the superior-temporal and inf-temp neuro retinal rim
-some come from peripheral retina; other start out more centrally

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15
Q

where do nasal fibers come from and where do they insert

A

nasal retinal fibers that insert into the nasal neuro retinal rim

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16
Q

where do the distal arcuates travel

wehre do the proximal arcuates travel

A

distal: travel at the bottom of the heap (closwer to RGC layer)
proximal: travel more superficially, on top of distal fibers (closwer to vitreous)

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17
Q

what position in the optic disc to distal arcuates occupy? proximal?

A

distal: occupy a more peripheral position in the optic disc (near disk margin)
proximal: occupy a more central position in the optic disc (nearer the cup)

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18
Q

although the papillomacular bundle starts out in the temporal neuro-retinal rim, they move to occupy a …in the optic nerve

A

central location in the optic nerve (closer to the chiasm)

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19
Q

a lesion in the posterior chiasm may cause a …

A

bitemporal hemianopia, denser below

bc the superior-nasal fibers cross in this portion of the chiasm

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20
Q

what happens in the anterior chiasmal syndrome

A

causes a junctionalscotoma

  • centrol loss (NFB defect) in one eye and superior-temopral loss in the opposite eye
  • bitemporal hemianopia (due to crossing nasal fibers) is denser sup earlier on the course of the dieases
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21
Q

where does the papillomacular bundle travel in the chiasm and where does it cross in the chiasm

A

travels inf in the chiasm and then crosses in the most posterior part of the chiasm

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22
Q

what kind of disease can affect temporal fibers

A

aneurysm of the ICA which can push on these temporal fibers to cuase a nasal vf defect one eye

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23
Q

what fibers are in the anteriro chiasm?
post chiasm?
what fibers are uncrossed?

A

ant: inf-nasal fibers (sup-temp field)
post: sup-nasal fibers (inf-temporal field)
- nasal macular fibers (papillomacular bundle)
uncrossed: temporal fibers (arcuates, temporal macular fibers)

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24
Q

what occurs in an ant chiasmal syndrome?
classical chiasmal syndrome?
post chiasmal syndrome?

A

ant: juctional scotoma
classic: bitemporal field loss
post: central bitemporal
- bitemporal denser below
- incongruous homonymous hemianopia (tract)

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25
Q

superior fibers are superior then move ____
inf fibers move _____
macular fibers are central and move ____

A

sup move medial
inf move lateral
macular fibers are central then move sup

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26
Q

where do the superior retinal quadrants synapse in? what kind of fibers

A

medial LGN
uncrossed ST fibers
crossed SN fibers

27
Q

wehre do the inf retinal quadrants synapse in

what kind of fibers

A

lateral LGN
uncrossed IT fibers
crossed IN fibers

28
Q

where do the macular fibers synapse in

what kind of fibers

A

intermediate LGN

  • sup macular fibers go to the medial aspect of the int LGN
  • inf macular fibers go to the lateral aspect of the int LGN
29
Q

the medial LGN contain fibers destined to _____ to the parietal lobe via the ____ radiations.
-represent ______ inf field info

A

the medial LGN contain fibers destined to head up to the pareital lobe via the sup radiations
-these head to the sup visual cortex and represent contralateral inf field info

30
Q

the lateral LGN contain fibers destined to _____ to the temporal lobe via the _____ radiations
-these head to the _____ visual cortex and represent contralateral ______ sup field info

A

the lateral LGN contain fibers destined to head down to the temporal lobe via the inf radiations
-these head to the inf visual cortex and represent contralateral sup field info

31
Q

a right LGN lesion will cuase a _______

A

left homonymous hemianopia

32
Q

optic radiations that go up DORSALLY to the parietal lobe carry info representing the _____ field

A

inf field

and sup retinal quad

33
Q

optic radiations that go down VENTRALLY to the temporal lobe represent info from the _____ field

A

sup field

and inf retinal quadrants

34
Q

what fissure separates the sup and inf visual cortex

A

calcarine fissure

35
Q

what tip is the most posterior part wehre the macular/central vision is represented

A

occipital tip

36
Q

what contain the axons of RGCs

A

retinal nerve fiber layer
optic nerve
optic chiasm
tract

37
Q

what are the 4 portions of the optic nerve

A

intraocular (ONH)
intraorbital
intracanalicular
intracranial

38
Q

what is the longest part of the optic nerve

A

intraorbital portion

39
Q

what are the lengths of the papilla, intraorbital, intraosseous, and intracranial

A

ONH aka papilla: 1mm
intraorbital: 30mm
intraosseous: 6mm
intracranial 10mm

40
Q

what are the 3 zones of the optic nerve head (aka intraocular optic nerve and papilla)

A
  1. prelaminar (ant)
  2. laminar
  3. retrolaminar (post )
41
Q

what are lamina cribosa

A

holes through which all RGC axons pass to exit the eye –(200-300 holes) through which all optic nerve axons pass

42
Q

what do axons of retinal ganglion cells become

A

optic nerve, chiasm, and tract

43
Q

where does the central retinal artery pierce the optic nerve sheath

A

10-12mm behind the globe and runs ant in the central aspect of the optic nerve to emerge in the center of the optic disc

44
Q

which bone is the intracanalicular portion in?

A

sphenoid, lesser wings

45
Q

in intraorbitla part goes from behind the ____ to the _____

A

ONH to the optic foramen

46
Q

the intracranial portion varies in length, which will afftect the position of what

A

of the optic chiasm over pituitary gland

47
Q

what ist he optic chaism superior to? how many mm

A

10mm above the pituitary gland

-which sits inside the sphenoid bone-the sella turcica

48
Q

the chiasm lies in the middle of the….

A

suprasella cistern

-CSF filled subarachnoid suprasellar cistern

49
Q

the pituitary gland is inf to the chiasm, so pituitary stalk to ______ to the optic chiasm

A

posterior

50
Q

in a craniopharyngiomas (usually at the junctin of the infundibulum and the pituitary gland) the turmos can compress the post optic chiasm, what compression can you get and what happens

A

you get a compression of the crossing sup nasal fibers which mediate inf temporal vision in each eye

-bitemporal hemianopia denser inferiorly

51
Q

the optic recess is one of the pointy parts ot he 3rd ventricle and is _____ nad ____ to the optic chiasm

A

right above and post to the optic chiasm

52
Q

how is the chiasm located in relation to they hypothalamus

A

chiasm is in front of and inf to the hypothalamus

53
Q

what ist he anterior and post bony boundary of the sella turcica

A

ant: tuberculum
post: dorsum

54
Q

what is a prefixed, normal, and postfixed chiasm?

A

normal: above the diaphrgma sellae
prefixed: intracranial optic nerves are short, the optic chiasm is positioned ant and sits over the tuberculum sellae
postfixed: intracranial nerves are long, the chiasm is positioned post to the dorsum sellae

55
Q

if you have a postfixed chiasm where the chiasm is “fixed” to the dorsum sellae, then if the pittuitary below were to expand larger than 10mm, what would you be more likely to compress? the ant, middle, or post chiasm?

A

ant chiasmal syndrom/junctional scotoma

56
Q

what can occur from a retrochiasmal lesion (meaning a lesion occuring anywehre starting behind the chiasm all the way to the visual cortex)

A

homonymous hemianopia

57
Q

why can you not get an RAPD from a lesion at the LGN, radiations, or visual cortex?

A

pupil light reflex pathway bypasses the LGN

58
Q

once the optic radiations leave the LGN, they traverse the most ______ aspect of the _______ . after this they course post to the visual cortex

A

most posterior aspect of the post limb of the internal capsule

59
Q

why is there meyer’s loop

A

the ventral horizontal bundle (inf optic rad) have to skirt around the inf horn of the lateral ventricle, which is in the temporal lobe

60
Q

If you have a lesion to the right occipital lobe above the calcarine fissure, what kind of field defect would you expect?

A

left inferior HH

61
Q

in the occipital lobe, if there is a lesion in the posterior region what thing will you get

A

highly congruous homonymous hemianopia

  • often respects both the vertical and horiz
  • a true qandrantonopia
62
Q

if there is a lesion in the ant occipital lobe what will you get

A

monocular temporal crescent

63
Q

what can be spared when there is a lesion in the occipital lobe

A

macula or temporal crescent may be spared

-macula represented at TIP (most post)

Neuro Final (10 decks)

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