Visual Pathway Flashcards
1
Q
centrocecal
A
includes fixation and the blind spot
2
Q
scotomas
A
Island defect surrounded by “seeing field”
3
Q
what is the optic chiasm surrounded by
A
circle of willis
4
Q
nerve fiber bundle defect
A
nasal step
-Defects on the horizontal midline nasally >15 degrees away from central fixation
5
Q
how many optic nerve fibers
A
1-2.2 million
6
Q
optic chiasm relations
A
- Posterior + inferior to the anterior cerebral + communicating arteries
- Medial to the internal carotid arteries
- Inferior to the third ventricle
- Superior to the pituitary gland
7
Q
striate connections
hypothalamus
A
circadian rhythm
8
Q
what is the diameter of the intraorbital portion of the nerve
A
diameter: 3mm
9
Q
pupils and optic tract
A
pupils affected if lesion is in the anterior 2/3 of the tract
10
Q
where is the first place that a single lesion will affect both eyes
A
optic chiasm
nasal fibers cross the midline
11
Q
optic radiation blood supply
middle radiations
A
deep optic branch of the middle cerebral artery
12
Q
where does myelination occur
A
only in he postlaminar region
13
Q
vertical organization
A
- ocular dominance columns
- columns for stimulus orientation
- -responds to the direction of light
14
Q
visual association areas names and functions
A
Brodmann areas 18, 19 now referred to as V2, V3, V4, V5
Functions as storage for visual patterns and recall
15
Q
bitemporal hemianopia most common cause
A
pituitary gland adenoma
16
Q
primary visual cortex blood supply
A
Calcarine branch of the posterior cerebral artery
17
Q
superior network blood supply to optic chiasm
A
- Anterior communicating artery
- Anterior cerebral artery
18
Q
LGN retinotopic representation
A
A given point in the visual field projects to a specific location in the LGN
Fibers from corresponding points in both retinas terminate in neighboring areas of adjacent LGN layers
19
Q
meyers loop
A
- part of inferior retina (temporal)
- must pass through the temporal lobe by looping around the inferior horn of the lateral ventricle.
20
Q
optic chiasm
superior nasal fibers
A
cross to the contralateral, medial optic tract
-posterior knees of wilbrand
21
Q
what does the calcarine fissure intersect
A
intersects the parietooccipital sulcus
22
Q
what is the lamina cribosa
A
network of scleral fibers where the optic nerve exits the eye
23
Q
To nucleus of the optic tract
A
Optokinetic nystagmus (OKN)
24
Q
superior field is imagined in
A
inferior retina
25
inferior nasal fibers
cross to the contralateral, lateral optic tract
| -anterior knees of wilbrand
26
function of visual cortex
- Process visual information
| - Integration of binocular information
27
optic tract lesions
right VF
left VF
- right vf carried in left optic tract
| - left vf carried in right optic tract
28
Paracentral scotoma
Does not affect fixation
29
Hemianopia or Hemianopsia
- homonymous defect extends past the 180th meridian
- involves half the visual field
- respects the vertical midline
30
retinotopic representation visual cortex
Adjacent fibers in the LGN project to adjacent areas in the visual cortex
31
temporal field imagined in
nasal retina
32
optic chiasm
| macular fibers
Macular fibers stay in the middle
- Temporal fibers
- Nasal fibers
- ---Cross to contralateral eye
33
temporal wedge
a small defect temporal to the blind spot
34
pericentral ring
Does not affect fixation
| Makes an annular pattern
35
synapse 3
LGN nucleus
| axons --> optic radiations
36
synapse 1
photoreceptor cell
37
list the parts of the ON longest to shortest
intraorbital > intracranial > intracanalicular > intraocular
38
homonymous
- eye in both eyes
- nasal in one eye, temporal in other
- respects the vertical midline
39
LGN relations
- Medial to the internal capsule
- Lateral to the medial geniculate nucleus
- Medial to the inferior horn of the lateral ventricle
40
anterior junction syndrome
- compression of the optic nerve at its junction with the chiasm
- central defect in ipsilateral eye
- pie in the sky in the contralateral eye
41
optic disc fibers
```
Nasal fibers
Temporal fibers
Superior fibers
Inferior fibers
Macular fibers
```
42
physiological blind spot
15 degrees temporal to fixation
43
a right homonymous hemianopsia lesion
left side
44
optic radiation blood supply
| posterior radiations
calcarine branch of the posterior cerebral artery
45
ganglion cell
axons (optic nerve) --> optic chiasm --> optic tract
46
optic radiations fibers
superior fibers --> parietal lobe
| inferior fibers --> temporal lobe
47
synapse 2
bipolar cell
48
post-chiasmal VF
binocular
49
post laminar blood supply
Ophthalmic artery
Central retinal artery,
Pial vessels
50
optic chiasm
| superior temporal fibers
exit to the medial optic tract
51
binasal hemianopia and chiasm
involves both lateral sides of the chiasm
52
magnocellular layers process..
horizontal organization
motion and low spatial frequency
53
intraocular nerve prelaminar
fascicles: sheaths of astrocytes bundle ~1000 fibers per fascicle
54
what surrounds the postlaminar region
EOMS
55
visual pathway order
retina --> ON --> optic chiasm --> optic tract --> LGN --> optic radiations --> striate cortex
56
blood supply to the ON
| prelaminar and laminar
peripapillary choroidal network, unfenestrated
57
what is optic tract
-flattened. cylindrical band of ganglion fibers from the optic chiasm to the LGN
58
what are the functions of the LGN
some visual processing
- Ensures the most important information is sent to the visual cortex
- Has a pathway to the visual cortex and other cortical areas
- Has a pathway from the visual cortex
59
optic radiation blood supply
| anterior radiations
anterior choroidal artery
60
what % of fibers from the optic tract go to the LGN
90%
61
frontal eye fields
Voluntary and reflexive binocular eye movements
62
synapse 4
visual cortex nucleus
63
retinal nerve fiber layer (RNFL)
- group of ganglion cells
- arcuate scotoma or nasal step
- horizontal midline typically respected
64
where is the LGN located
on the dorsolateral portion of the pulvinar thalamus
65
optic tract blood supply
- anterior choroidal
| - middle cerebral
66
arcuate scotoma
Complete or incomplete/partial
| Double arcuate
67
optic chiasm
| inferior temporal fibers
exit to the lateral optic tract
68
optic nerve fibers
- Distal from the chiasm
- Proximal to the chiasm
- --Macular fibers move to the center
69
LGN vf loss
homonymous loss
70
posterior lesion
congruent
71
marginal tissue (of Elschnig)
connective tissue continuous with the sclera
72
other names for primary visual cortex
striate cortex, brodmann area 17, v1
73
where do retinal axons terminate
LGN
74
anterior lesion
incongruent
75
what is the function of glial tissue (ON)
separates the nerve from the retina, choroid, sclera
76
primary visual cortex location
- medial portion of the occipital lobe
| - line of Gennari runs near the calcarine fissure
77
intraocular nerve laminar
within the lamina cribosa
78
what part of the ON is the post laminar
intraorbital
79
Each layer receives information from only one eye at the LGN
2,3,5 ipsilateral
| 1,4,6 contralateral
80
10% of fibers from optic tract go where
pretectal area,
superior colliculus
hypothalamas
81
central or centrocecal defect ON
(+) APD, afferent pupillary defect
82
LGN blood supply
- Anterior choroidal artery
| - Posterior choroidal artery
83
optic tract fibers
Ipsilateral temporal fibers and contralateral nasal fibers are now grouped
-macular fibers are in the middle
84
pre-chiasmal VF
monocular
85
optic tract relations
- Lateral to cerebral peduncle
- Parallel to the posterior cerebral artery
- Inferior to the globus pallidus
86
cecal
enlarged blind spot
87
optic radiation fibers
fibers fan out passing through the parietal and temporal lobes
88
congruency and chiasm
incongruent- closer to chiasm
| congruent- further from the chiasm
89
what is affected first with compression to ON
macular fibers
90
altitudinal
-Upper or lower half of the field affected
-Respects the horizontal midline
Unilateral
Bilateral
91
meyers loop lesion
a lesion in the temporal lobe that results in damage to Meyer's loop causes a characteristic loss of vision in a superior quadrant (quadrantanopia or "pie in the sky" defect.)
92
bilateral altudinal
Damage to the upper or lower calcarine fissure of both eyes
93
temporal crescent
- Portion of the peripheral field without a counterpart in the nasal field of the other eye
- Located very _anterior__ in the visual cortex
94
inferior network blood supply to optic chiasm
- Posterior communicating artery
- Posterior cerebral artery
- Internal carotid artery
95
optic radiation relations
-lateral to the inferior horn of the lateral ventricles
96
what bigger structure of the brain is the LGN apart of
thalamus
97
what bone does the ON go through
lesser wing of the sphenoid bone
98
optic radiations vf loss
likely a quadranopsia
99
intermediary tissue (of kuhnt)
glial tissue separating the retina
100
what are the 6 layers of the LGN
layers 1-2 = magnocellular layer
Layer 3-6 = parvocellular layer
koniocellular dispersed around
101
meyers loop carry info from
carry information from the superior part of the visual field
102
visual cortex fibers
superior fibers --> cuneus gyrus
inferior fibers --> lingual gyrus
macular fibers run more posterior
103
intraorbital: postlaminar
fascicles acquire a connective tissue sheath and become myelinated by oligodendrocytes
104
post-chiasmal lesions
damage affects the contralateral field
| -vertical midline respected
105
border tissue (of jacoby)
glial tissue separating the choroid
106
what is the horizontal diameter of ONH
1.5mm (1500 um)
107
pituitary gland location
located inferior to the optic chiasm
108
blood supply to intracranial
Ophthalmic artery
Anterior cerebral artery
Anterior communicating artery
Internal carotid artery
109
what sheaths are attached to the optic nerve
EOM
| MR and SR
110
anatomical location
- inferior to the olfactory tract
- inferior to anterior cerebral artery
- superior + medial to the ICA
- lateral to the sphenoid body
111
retinal nerve fiber layer
- ganglion cell axons
- papillomacular bundle
- horizontal raphe
112
cuneus lingual
cuneus- upper
| lingual- lower
113
parvocellular layers process..
horizontal organization
color and high spatial frequency
114
visual cortex vf loss
- congruent homonymous hemianopia
| - VA usually not affected
115
right side of VF imagined in
nasal retina in right eye
| temporal retina in the left eye
116
heteronymous
fields of both eyes show on opposite sides
- bitemporal
- binasal
117
striate connections
| superior colliculus
fixation and saccades
