Visual Pathway Flashcards
What are the 2 types of ganglion cells according to the type of information they process?
magnocellular which provide information about motion and parvocellular which provide information about colour and are important for visual acuity
What percentage of the ganglion cells are parvocellular?
80%
What is the major target for ganglion cell axons?
the lateral geniculate nucleus of the thalamus
Which structures in the brain are located close to the optic chiasm?
pituitary gland and the internal carotids
What is the most common cause of tunnel vision?
a tumour of the pituitary gland which impacts on the optic chiasm
Which part of the brain is the right visual hemisphere viewed by?
the left hemisphere
Which layers of the LGN are magnocellular?
layers 1 and 2
Which layers of the LGN are from the left eye?
1, 4, 6
What are optic radiations?
the white matter tract from the LGN to the occipital lobe
Which fissure does the visual cortex sit around?
the calcarine fissure
Where is central vision represented in the occipital cortex?
the most posterior part of the occipital lobe
Where is the lesion when the visual field of only one eye is effected?
before the optic chiasm
Where is the lesion when the temporal sides of both visual fields is affected?
at the optic chiasm
Where is the lesion when the same half of the visual field is affected for both eyes?
after the optic chiasm
What is the cause of the lesion when half the visual field is affected but spares the central part of the visual field?
a vascular problem - because the most posterior part of the occipital lobe is supplied by a branch of a different artery than what supplies the rest of the occipital lobe
