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The Retinofugal Projection & LGN - Coggle Diagram
The Retinofugal Projection & LGN
What is the scheme of the retinofugal projection (the neural pathway that leaves the eye, beginning with the optic nerve)? Where does the LGN lie in this projection?
ganglion axons go away from the retina
the brain stem
optic nerve
optic chiasm
optic tract
run just under the pia along the lateral surfaces of the diencephalon
small number of axons: connect with hypothalamus
synchronizing biological rhythms
some continue past the thalamus to innervate the midbrain
pretectum 👀💨 (part of the midbrain)
control the size of the pupil and certain types of eye movement
about 10% of the ganglion cells in the retina project to
the
superior colliculus
part of the midbrain tectum 🗻
involved in orienting the eyes in response to new stimuli in the visual
periphery
most !!! of them innervate the
lateral geniculate nucleus (LGN)
of the dorsal thalamus :one: :eye:
neurons in the LGN give rise to axons that project to the primary visual cortex
this projection from the LGN to the cortex is called the
optic radiation
☢️
2 LGNs: right and left
organization
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right LGN receives information about the left visual field :left_right_arrow:
lies at the base of the brain
axons originating in the
nasal
retinas cross from one side to the other :nose::crossed_swords:
since only the axons originating in the nasal retinas (HALF the axons) cross → it's called a
partial
decussation of the retinofugal projection
implications for the visual field
full
visual field
entire region of space (measured in degrees of visual angle) that can be seen with both eyes looking straight ahead
midline: a vertical line, dividing the visual field into left and right halves
each half is known as a
visual hemifield
binocular visual field
central portion of both visual hemifields viewed by both retinas
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exit the left and right eyes at the optic disks 📀
travel through the fatty tissue behind the eyes
pass through holes in the floor ⬇️ of the skull
optic nerves from both eyes combine to form