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NEURO > VISUAL PATHWAY > Flashcards

VISUAL PATHWAY Flashcards

1
Q

AFFERENT FROM EYES TO BRAIN:

CN II SSA function?

A

vision and pupillary constriction

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2
Q

CN V GSA function?

A

Ocular pain
Tearing reflex
Corneal reflex
Proprioception from extraocular muscles

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3
Q

What are the 3 intraocular muscles?

A

Pupiloconstrictor
Ciliary muscle
Pupilodilator

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4
Q

intraocular muscle that has a sympathetic function? the other two function as ___

A

Pupilodilator muscle, parasympathetic

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5
Q

Image is inverted in retina, therefore:

A

Upper visual space to lower retina
Lower visual space to upper retina
Right visual space to left hemiretina
Left visual space to right hemiretina

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6
Q

125 million photoreceptors found within
Light passes through the lens

A

EYES AND RETINA

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7
Q

Central fixation point of EYES AND RETINA

A

fovea

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8
Q

Highest visual acuity
Represented by half of the optic nerve fibers and half of the cells in primary visual cortex

A

fovea

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9
Q

fovea is surrounded by

A

macula lutea

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10
Q

No photoreceptors
15 degrees medial (nasal) to the fovea

A

Optic disc

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11
Q

area where Axons of ganglion cells leaving the retina gather to form the optic nerve

A

Optic disc

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12
Q

Since there is no photo receptors________ has 15 degrees lateral (temporal) and slightly inferior to the central fixation point for each eye

A

Blind spot

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13
Q

More numerous than cones (20:1)

Relatively poor spatial and temporal resolution of visual stimuli

A

Rods

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14
Q

Less numerous overall but highly represented in the fovea

Numerous in fovea

High spatial and temporal resolution

A

Cones

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15
Q

Do not detect colors
Specifically used in night vision as it cannot detect colors

Vision in low-level lighting conditions = night vision

A

Rods

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16
Q

Detect colors

Visual acuity

A

Cones

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17
Q

form the outermost layer, farthest from the lens

A

Photoreceptors

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18
Q

other layers of the retina are not present, allowing light to reach the photoreceptors without distortion

A

Fovea

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19
Q

the proportion of visual field where light causes excitation or inhibition of the

Area that is stimulated

A

Receptive field

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20
Q

Photoreceptors respond to light in their receptive field and form excitatory or inhibitory synapses onto ___________

A

bipolar cells

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21
Q

Bipolar cells synapse with ________________whose axons are sent to the optic nerve

A

Ganglion cells

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22
Q

Ganglion cells axons becomes the _____________

A

Optic nerve

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23
Q

Retinal ganglion cells have 2 types:

A

Parasol cells (A cells)\

Midget cells (B cells)

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24
Q

small receptive field, sensitive to fine visual details and color; project to parvocellular layers of LGB

A

Midget cells (B cells)

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25
Q

large receptive field, movement and gross stimulus features; project to magnocellular layers of LGB

A

Parasol cells (A cells)

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26
Q

Horizontal cells

Amacrine cells

Lateral inhibitory or excitatory connections with nearby bipolar and ganglion cells

A

Interneurons

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27
Q

when bipolar and ganglion cells are excited, surrounding cells are _________

A

Inhibited

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28
Q

ARRANGEMENT OF VISUAL FIELD

A

From eyes → optic nerve → optic chiasm → optic tract → LGB → optic radiation → loops around in temporal lobe (Meyer’s Loop) → primary vision cortex

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29
Q

Axons of retinal ganglion cells
Exit via optic canal of sphenoid bone to enter the cranium

A

OPTIC NERVES

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30
Q

Lesions of eye, retina, or optic nerve produce

A

monocular visual field defect

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31
Q

Located on ventral surface of midbrain, beneath the frontal lobes and just on top of the pituitary gland

A

OPTIC CHIASM

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32
Q

Partial crossing of nasal (medial) retinal fibers

Fibers from the left hemiretina of both eyes end up in left optic tract

A

OPTIC CHIASM

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33
Q

Lesions of optic chiasm often produce

A

bitemporal (bilateral lateral) visual field defect also called

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34
Q

Lesion on optic chiasm = no vision on

A

bilateral nasal vision also called Bitemporal hemianopsia

35
Q

Lesion on optic nerve = no vision on

A

bilateral temporal vision

36
Q

Wrap around the midbrain laterally to the LGB of the thalamus

A

OPTIC TRACT

37
Q

Lesions posterior to the optic chiasm (optic tracts, LGB, optic radiations, visual cortex)

A

homonymous visual field defects
or same side

38
Q

LATERAL GENICULATE NUCLEUS AND EXTRAGENICULATE PATHWAYS:

A

axons of retinal ganglion cells→ LGB neurons→primary visual cortex

Note: Some fibers bypass the LGB to enter the brachium of the superior colliculus to project to the pretectal area and superior colliculus

39
Q

After the stimulus goes to the pretectal area and superior colliculus it would go to?

A

EDW nucleus (PSY)

40
Q

direct visual attention and visual attention and eye movements toward visual stimuli; project to numerous brainstem areas involved as well as association cortex (lateral parietal cortex and frontal eye fields) via relays in pulvinar and lateral posterior nucleus of thalamus

A

Superior colliculus and pretectal area

41
Q

Fan out over a wide area

A

optic radiation

41
Q

Axons of LGB enter the white matter to sweep over and lateral to the atrium and temporal horn of the lateral ventricle and then back to the _________________

A

primary visual cortex

41
Q

Inferior optic radiations carry information from inferior __________________________

A

retina (superior visual field)

42
Q

fibers of the inferior optic radiations arc forward into the temporal lobe

Inferior portion of optic radiation

A

Meyer’s loop

43
Q

contralateral homonymous superior quadrantanopia

A

Temporal lobe lesions

44
Q

Upper portions of the optic radiation project to the superior bank of the calcarine fissure

A

contralateral inferior quadrant defects

45
Q

Inferior optic radiations terminate on the lower bank of the calcarine fissure

A

contralateral superior quadrant defects

46
Q

Retinotopically organized

Fovea - represented near the occipital pole

More peripheral regions of ipsilateral and contralateral visual fields are more anterior along the calcarine fissure

A

PRIMARY VISUAL CORTEX

46
Q

Lesion on retina with location, size and shape of scotoma depends on the location and extent of the lesion

A

Monocular Scotoma

Note: If lesion on retina is big enough can cause - monocular visual loss

46
Q

Retinal disorders
Lesion of optic nerve

A

Monocular visual loss

47
Q

Lesion in optic chiasm
If lesion here = both sides ng nasal side will be loss

Pituitary gland tumor, pituitary macroadenoma (enlargement of pituitary gland which can cause^)

A

Bitemporal Hemianopia

48
Q

Retrochiasmal lesion - optic tracts, LGN, optic radiation or visual cortex

A

Homonymous Visual Field Deficit

49
Q

Lesion of optic tract
Lesion of LGB
Lesion of entire optic radiation
Lesion of entire primary visual cortex
(D, G, H) Contralateral homonymous hemianopia

A

Contralateral Homonymous Hemianopia

49
Q

Lesions of temporal lobe through meyer’s loop of lower optic radiation

aka Pie in the sky

Lesion to the lower bank of calcarine fissure

Cannot see on affected lower quadrant side

A

Contralateral Superior

Quadrantanopia

50
Q

Lesions of parietal lobe involving the upper portions of the optic radiations

Pie on the floor

Lesions of upper bank of the calcarine fissure

A

Contralateral Inferior

Quadrantanopia

50
Q

Partial lesions of visual pathways

Fovea has relatively large representation from the optic nerve to the primary visual cortex

Can occur in the visual cortex due to collateral flow between MCA and PCA

A

Macular Sparing

51
Q

Finds, fixates, focuses/aligns on and follows visual targets

A

foveates

52
Q

To align each eye to cause the central light to fall on the fovea and the entire retinal image to fall on corresponding retinal points of both eyes

A

OCULOMOTOR SYSTEM

53
Q

elevates eyelids, sympathetic (states of sympathetic predominance and static tone or maintenance)

A

Superior tarsal muscle (Muller’s muscle)

54
Q

elevates eyelids

A

Levator palpebrae superioris

55
Q

controls lens

A

Ciliary muscles

56
Q

Activation of ________causing bilateral pupillary constriction and contraction of ciliary muscles of the lens

A

pretectal nuclei

57
Q

Activated by visual signals relayed to the visual cortex

A

ACCOMMODATION REFLEX

58
Q

Ciliary muscle acts as a _____________
When ciliary muscle contracts, it causes the suspensory ligament to relax, producing a rounder, more convex lens

A

Sphincter

59
Q

For near vision
Convergence by medial recti – aims the visual axes onto the near fixation point
Pupillary constriction by pupillary constrictor muscles of the iris (PSY)
Lens thickening by ciliary muscles (PSY)

A

ACCOMMODATION REFLEX

59
Q

Lens is normally under tension from

A

suspensory ligament

60
Q

PUPILLARY DILATION - SYMPATHETIC

A

Descending sympathetic pathway→lateral brainstem and spinal cord to T1 and T2.
→Activates preganglionic SY neurons →Axons exit via ventral T1 and T2 ventral roots→paravertebral SY→superior cervical ganglion
→Postganglionic SY fibers →pupillary dilator muscles

61
Q

Eyelid Elevation

A

Superior tarsal (Muller) muscle - tonically elevates the eyelid; innervated by carotid sympathetic nerve
Levator palpebrae muscle - tonically and phasically elevate the eyelid; innervated by CN IlI

61
Q

ptosis, miosis and anhidrosis

A

Horner’s syndrome

62
Q

Eyelid Closure

A

Orbicularis oculi muscle - CN VII

63
Q

All voluntary horizontal and vertical eye movement
Rapid eye movements in sleep
Bring target of interest into field of view
Vision transiently suppressed

A

Fast, physiologic = Saccades

64
Q

allow stable view of moving objects

A

Smooth pursuit

65
Q

maintains fused fixation as targets move towards or away

A

Vergence

66
Q

rhythmic form of reflex eye movement composed of slow eye movement in one direction, interrupted repeatedly by fast, saccade-like eye movement in the opposite direction

Vestibulo-ocular reflex

A

Nystagmus

67
Q

interconnects the CN III, CN IV, CN VI and CN Ill nuclei; eye movements are yoked together for conjugate eye movement in all directions

A

Medial Longitudinal Fasciculus (MLF)

68
Q

Responsible for left and right deviation of the eye (horizontal movements)

A

Paramedian Pontine Reticular Formation (PPRF)

69
Q

SR, IR, SO and IO
Located in rostral midbrain reticular formation and pretectal area

A

Vertical eye movements

70
Q

Ventral portion - _________
Dorsal portion - _________
Rostral interstitial nucleus of MLF - ____________

A

downgaze, upgaze, mediate downgaze

71
Q

generate saccades in contralateral direction via connections with contralateral PPRF

A

Frontal Eye Fields (BA 8)

71
Q

saccadic brainstem center for vertical eye movements

A

Rostral interstitial nucleus of the MLF

72
Q

modulate eye movement

A

Basal Ganglia

72
Q

PPRF

A

Paramedian Pontine Reticular Formation (PPRF)

72
Q

for smooth pursuit movements in the ipsilateral direction via connections with vestibular nuclei, cerebellum, PPRF

A

Parieto-Occipito-Temporal Cortex

NEURO (7 decks)

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