Visual Pathways Flashcards
Optic tracts after leaving the optic chiasm arrive at what nucleus
The Lateral Geniculate Nucleus
Superior Optic radiations carry what optic fibres?
Superior quadrant fibres through the parietal lobe
A lesion to an optic nerve before it reaches the optic chiasm causes what type of visual defect
Monocular Blindness. Total blindness to 1 eye
A lesion at the optic chiasm like seen in a pituitary adenoma causes what type of visual defect?
Bitemporal hemianopia
A lesion to the optic tracts would cause what form of visual defect?
Homonomous Hemianopia. Complete loss of vision to the ipsilateral side of each eye
A lesion in the optic radiations would be called what?
Homonomous Inferior/Superior Quadrantanopia
Why is the Macula spared in a stroke effecting the Posterior Cerebral Artery
The pole of the occipital lobe is spared as it’s supplied by the middle cerebral artery. This area is responsible for Macula function.
What are the 3 changes in the eye seen in the accommodation reflex. Hint 3Cs
Convergence (Medial Rectus)
Pupillary Constriction (Constrictor Pupillae)
Convexity of the lens (Cilliary Muscle)
Parasympathetics of CN III are responsible for pupil constriction and lens thickening. What nucleus in the midbrain is responsible for this efferent neurone?
Edinger-Westphal Nucleus
How does Retinal pigment improve acuity?
It prevents light from over refraction so a lack of this can lead to glare
How do Horizontal Cells improve lights focus?
Through Lateral Inhibition they inhibit photoreceptors proximal to the focus
A clot in the central retinal artery causing transient loss of vision to an eye is known as what?
Amaurosis Fugax
