Test 2: Visual Flashcards Preview

Neuro Anatomy > Test 2: Visual > Flashcards

Flashcards in Test 2: Visual Deck (37):
1

What CN does vision

CN II- optic nerve

2

Why is CNII NOT a peripheral nerve?

retinal structure from diencephalon development
myelinated neurons with oligodendycytes-CNS

3

What is the pathway of light traveling into the eye?

Iris through lens to retina- focused on fovea to optic nerve

4

What does the pupillary constrictor muscle do?

controls amount of light entering the eye via controlling the iris
-parasympathetic constricts
-synpathetic relaxes

5

What do ciliary muscles do?

adjusts lens thickness to help bend light to focal point (fovea)
-visual accomodation
-paraysmp: thickens
-sympathetic relaxes

6

What is the retina? what's in it?

has visual receptors lining the walls of the eye
-macula on posterior wall= increase density
-fovea in macula= highest density of cones

7

What is the optic disk? what's in it?

blind spot
-axons from retina and vasculature exit through here
-vascular from internal carotid-opthalamic vessels

8

What makes up the fovea?

5 types of neurons
-mainly photoreceptors= rods and cones
-retinal ganglia cells

Everything flipped upside down!!

9

What are rods?

photoreceptor in fovea
-ALL wavelengths visible light
-dense around macula
-detects light levels and motion-- course vision

10

What are cones?

photreceptor in fovea
-3 types of pigements to transduce color wavelenths: red, green, blue
-most dense around fovea where macula has greatest visual acquity

11

What are retinal ganglia?

output neurons- 1CB of visual pathway
-axons collect at optic disk and once exit eye all travel as CNII
-unmeylinated axons until exit disk-> myelinated with oligodend

12

What are pigment epitheliums? what are the 3 types?

melanin that absorbs light to decrease scatter

1. opesins: photo pigment for color
2. rodespin: light/dark
3. melanopsin: special ganglia with melanin

13

What are the 4 possible pathways of visual perception?

1. Primary pathway-> V1
-occipital pole

2. Suprachiasm nucleus of hypothal
-diurnal clock
-light/dark
-melanopsin

3. Pretectal nuclei (midbrain)
-pupil constrictor/thicken lens
-parasympathetic reflexes

4. Superior colliculus (midbrain)
-eye movements relative to environment

14

What is the 1neron characteristic of the Primary Visual pathway?

axons off of photoreceptors
-collect/sort 3 regions of projections
-all axons travel in ipsilateral optic nerve
-enter chiasm: vulnerable to pituitary tumor damage

Nasal: 60% decussate in chiasm-> contrlateral optic tract
Temporal: 40% stay ipsilateral-> ipsilateral optic tract

Tracts-> LGN -> internal capsule -> optic radiations -> VI

15

What is the BA number of V1

BA 17

16

What are the layers of the LGN

4 parvocellar layers: show color
2 magnocellar layers: percieve motion

17

What is the striate cortex?

superior and inferior banks by calcacrine sulcus

Inferior visual field goes up through parietal to SUP bank

Superior visual field goes down through temporal to INF bank
-some bend around inferior horn of lateral ventricles= Meyers loop

18

What is the monocular visual field?

Vision of one eye
-seperate into 4 quadrants: superior, inferior, nasal, and temporal

TEMP CRESCENTS 930 deg) project to NASAL retina

19

What is the binocular visual field?

Detected by both eyes
-majority of visual field except small monocular temporal crescents

MOST (90 deg) projects to BILAT TEMPORAL retina

20

What do the extraocular muscles do in relationship to convergence?

control eye alignment- focul point on fovea
-converge to fovea to get optimal visual acuity

21

How does the light refract through lens and in brain?

Inverted through lens onto retina
-inferior field on top
-superior field on bottom

L and right fields are flipped
-temporal visual field of L eye projects to nasal retina of left eye

22

Where do the R visual fields project in the brain?

LEFT V1

23

What does damage to the L eye/optic nerve result in?

Ipsilateral blindness
-can't see from L eye
-monocular field deficit

24

What does damage to the L optic chiasm do?

Bitemporal meianopia
-impaired peripheral vision bilaterall
-affects nasal retina axons at decussations

25

What does damage to the L optic tract do?

contrlateral homonomous hemianopnia
-impaired visual field contrlateral to tract
-R peripheral vision and left nasal vision

26

What does damage to LGN axons around inferior horn do?

Superior portion of contrlateral homonomous
-1/4 field okay

27

Why does macular sparing occur?

Redundant sampling of each quadrant
OR
MCA and ACA blood supply

28

What is the pathways of the pupilary light reflexes?

Retinal ganglia cells down CNII bypass LGN-> Pretectal nucleus
Pretectal-> BILAT Ed-West nucleus
Ed West-> ciliary ganglia via CNIII )oculomotor)
Ciliary ganglia-> pupilary constrictor muscle

29

Where is the CB of post-ganglionic nucleus in pupilary reflex?

ciliary gangliaa(along CNIII)

30

Where are the CB of pre-ganglionic neurons in pupilary reflex?

Ed-westphal

31

What is the area called where axons decussate from pretectub to contrlat E-W?

posterior commisure

32

What is it called when the ipsilateral eye reflex contracts? Contralateral? Both at once?

Direct
Indirect
Consensual

33

How would a lesion of the ipsilateral optic nerve affect pupilary reflex?

Direct and indirect Absent

34

How would a lesion to the contralteral optic nerve affect pupilary reflex?

Direct and Indirect Present

35

How would ipsilateral lesion to oculomotor nerve affect reflex?

Direct absent
Indirect present

36

How would contrlateral lesion to oculomotor nerve affect reflex?

Direct present
indirect Absent

37

What is the fusiform gyrus?

Occipotemporal gyri
-source of facial representations
-can get hallucinations if spontaneously activate
-primary visual lesions can cause association areas like this to fire sporadically