Visual Pathway Flashcards
The visual field of each eye is separated into…
Four quadrants:
Upper & Lower
Right & Left (nasal & temporal)
The retina receives…
Visual field projection
In the retina, the image is…
Crossed & inverted
The temporal 1/2 of the visual field projects to the ____ of the retina
Nasal 1/2
The nasal 1/2 of the visual field projects to the _____ of the retina
Temporal 1/2
The upper 1/2 of the visual field projects to the ____ of the retina
Lower 1/2
The lower 1/2 of the visual field projects to the ____ of the retina
Upper 1/2
In the optic chasm, fibers partially cross so that the left 1/2s of the visual field enter the ____ optic tract, and the right 1/2s of the visual field enter the ____ optic tract
Right
Left
The optic tracts synapse in the ____
Lateral geniculate nuclei
Fibers from the lateral geniculate nuclei form the ____
Optic radiation
The optic radiation fibers that correspond to the upper 1/2 of the visual field form the _____ in the ____ lobe
Loop of Meyer
Temporal
The optic radiation fibers that correspond to the lower 1/2 of the visual field form the ____
Parietal lobe optic radiation
The optic radiation from the loop of Meyer terminate at the ____, carrying visual information from the ____ visual field
Lingual gyrus
Upper
The optic radiation fibers from the parietal lobe terminate in the ____, carrying visual information from the ____ visual field
Cuneus
Lower
Lesion of right optic nerve
Right anopsia
(Loss of vision in right eye only)
Pituitary tumour affecting the optic chiasm (saggital)
Bitemporal hemianopsia
(Loss of peripheral/temporal vision)
Right carotid aneurysm affecting the optic chiasm (horizontal)
Right nasal hemianopsia
Lesion of right optic tract/LGB/optic radiation/visual cortex
left homonymous hemianopsia
(loss of vision of left visual field)
Lesion of right visual cortex (cuneus & lingual) excluding occipital pole
Left homonymous hemianopsia with sparing of macula
(loss of vision of left visual field, sparing central vision)
lesion of right parietal lobe optic radiation/cuneus
left homonymous lower quadrantanopsia
(loss of vision of lower left quadrant visual field)
lesion of right cuneus excluding occipital pole
left homonymous lower quadrantanopsia with sparing of macula
(loss of vision of lower left quadrant visual field, sparing central vision)
lesion of right loop of Meyer/temporal lobe optic radiation
left homonymous upper quadrantanopsia
(loss of vision of upper left quadrant visual field)
bilateral internal carotid aneurism affecting optic chiasm (horizontal)
binasal anopsia
lesion of right lingual gyrus excluding occipital pole
left homonymous upper quadrantanopsia with sparing of macula
(loss of vision of upper left quadrant visual field, sparing central vision)
activation of the light reflex causes…
constriction of pupils (sphincter pupillae mm)
what is the accommodation reflex?
convergence, thickening of lens & pupillary constriction
light entering the right eye will cause…
direct right pupil constriction
indirect left pupil constriction
light entering the left eye will cause…
direct left pupil constriction
indirect right pupil constriction
what happens when light enters the right eye with a lesion of the right optic nerve?
no pupil constriction
what happens when light enters the left eye with a lesion of the right optic nerve?
bilateral pupil constriction
what happens when light enters the right eye with a lesion of the right oculomotor nerve?
- right pupil cannot constrict (mydriasis)
- left pupil constricts
what happens when light enters the left eye with a lesion of the right oculomotor nerve?
- right pupil cannot constrict (mydriasis)
- left pupil constricts
what is Argyle Robertson Pupil?
mydriasis without cycloplegia
(Accommodation Reflex Present, Light Reflex Absent)
In the primary visual cortex, what structure separates the upper and lower visual fields?
calcarine sulcus
describe the pathway of the light reflex
LIGHT -> retina -> CN II -> optic tract -> sup. brachium
–< pretectal nucleus (bilateral; sup colliculi)
–< edinger-wesphal nuclei -> CN III
–< ciliary ganglion -> short ciliary n
–< sphincter pupillae mm
describe the pathway of the accommodation reflex
retina -> CN II -> optic tract
–< LGB -> optic radiation
–< visual cortex -> frontal eye field (8) -> corticobulbar tract
–< pretectal nuclei (bilateral; sup colliculi)
–< edinger-westphal nuclei -> CN III
–< ciliary ganglion -> short ciliary nn
–< ciliaris (lens) & sphincter pupillae (constriction) mm
what are saccadic movements (saccades)?
high velocity eye movements that orient the eyes toward a stimulus
what are the combined functions of the superior colliculus and frontal eye field related to saccadic movements?
coordinate visual, somatic, and auditory info, adjusting movements of the head to the stimulus
what are the functions of the superior colliculus related to saccadic movements?
receives info about motion in the visual field and is concerned with visual attentiveness and identification of broad outlines of objects
what are the functions of the frontal eye field related to saccadic movements?
receives info from primary visual cortex and is concerned with fine visual discrimination and saccadic movements to complex visual stimuli
