Visual System Flashcards
The upper nasal visual quadrant projects to the ____
Lower temporal retinal quadrant
The lower nasal visual quadrant projects to the ___
Upper temporal retinal quadrant
The upper temporal visual quadrant projects to the __
Lower nasal retinal quadrant
The lower temporal visual quadrant projects to the __
Upper nasal retinal quadrant
Where do fibers from the temporal hemiretina and nasal hemiretina cross?
Fibers from temporal hemiretina do not cross in the optic chiasma
Nasal hemiretina fibers cross in the optic chiasma
What is the rule of L’s?
Information from lower hemiretina projects to lateral part of lateral geniculate body, loop of Meyer, and lingual gyrus
What do homonymous visual fields refer to?
Corresponding halves of visual fields such as temporal field of one eye and nasal field of other
What do heteronymous visual fields refer to?
Noncorresponding visual fields like temporal field of one eye and temporal field of other
What does a unilateral lesion of the optic nerve result in?
Monocular blindness
What is binasal hemianopia?
Bilateral lesion of lateral aspect of optic chiasma
Results in hetronymous blindness in nasal fields of each eye
May also be unilateral since it is frequently due to atherosclerosis of internal carotid arteries
What does a unilateral lesion of the lateral aspect of the optic chiasma result in?
Nasal hemianopia of ipsilateral eye
What is bitemporal hemianopia?
May be due to midline lesion of medial portion of optic chiasma
Heteronymous deficit is usually caused by pituitary tumors
What is contralateral homonymous hemianopia?
Result of unilateral lesions of lateral geniculate body, complete optic radiations, or visual cortex
What is contralateral superior quadrantanopia?
Result of unilateral lesions of loop of Meyer
May be caused by tumor or infarction in posterior temporal lobe
What is incongruent contralateral homonymous hemianopia with macular sparing?
Usually indicative of a unilateral lesion of visual cortex
May be due to obstruction of posterior cerebral artery
Lesions of visual cortex are usually incongruous (asymmetrical), whereas lesions of LGB or optic radiations are congruous in their visual field deficits
The pretectum is important for the ___ reflex, while the posterior commissure is important for the ___ reflex
Direct light
Consensual light
Describe accommodation
Cortically mediated visual response
Originates in frontal eye field of the frontal lobe
The triad of accommodation includes convergence of vision, pupillary constriction, and thickening of the lens
What is Holmes-Adie Pupil (Tonic pupil)?
Benign condition, which may be due to lesion of ciliary ganglion
Initially, tonic pupil does not appear to react to convergence
If convergence is maintained for several seconds, the pupil will slowly constrict and will eventually be smaller than the normal pupil
It also constricts in response to parasympathomimetic agents, but the normal pupil does not
What controls nonvolitional eye movements? Volitional eye movements?
Occipital eye field
Frontal eye field
The visual projects __ image onto retinal field
Inverted and reversed
