Histo and optic tracts of the eye Flashcards
Levels of the corneoscleral coat
first is the Sclera: thick fibrous opaque layer piereced by BVs nerves and posteriorly by the optic nerve
Corneal epithelium: nonkeratinized stratified squamous cells
Bowmans membrane: anterior base membrane
Corneal stroma: unique orientation of cells and stroma; avascular
Descemets membrane: posterior base membrane
Corneal endothelium: simple squamous epithelium facing anterior chamber
Levels of the lens
Capsule: made of flexible elastic ECM
Subcapsular: lens epithelium cells on the periphery proliferate and migrate to make mature lens fibers cells
Lens fibers: filled with crystallins and lose all organelles
-central lens nucleus laid down during embryonic/fetal development
Lens accomadation
lens flat to see far away = relaxation of cilary muscle to ftighten the zonular fibers
lens round to see close = tightening of the ciliary muscle to relax the zonular fibers to let the lens ball up
What are the Retinal layers
Retinal pigmented layers
Photoreceptor layer
Outer limiting membrane
Outer nuclear layer: contain cell bodies of rods and cones
Outer plexiform layer
Inner nuclear layer: contains cell bodies of glial cells
Inner plexiform layer
Ganglion layer: cell bodies of ganglion cells
Layer of optic nerve fibers
Inner limiting membrane
What is the pathway of the light and neuron signal
the light will travel in and go all the way back to the Pigmented epithelium (back of the retina)
then the signal will travel anterior to the nerve fiber layer and travel transversely to the optic nerve/disk
Fovea Centralis
Highest visual acuity
Highest concentration of cones
absence of vessels cell bodies and axons of ganglionic and inner nuclear layer (stuff in the way of the cones and the light
Macula Lutea
Surrounds the Fovea
Antioxidant properties and short wave UV filter
Protects the cones of the FOvea
Optic Disk
Located at head of optic nerve
Gganglion axons from all of retina converge and dive
lack photoreceptors - only ganglion cells
Blind spot
Temporal part of the retina will see the?
contralateral visual hemifield
The nasal part of the retina will see?
the ipsilateral visual hemifield
The superior retina will see?
The Inferior visual hemifield
The inferior retina will see?
the superior visual hemifield
What is the importance of the decussation at the optic chiasm
Brings information together from comparable areas of both retinas to help with depth perception
What retinal areas cross at the optic chiasm
the nasal retina and its corresponding visual fields (ipsilateral visual field)
What synapses at the Lateral genticulate ganglion
ipsilateral temporal retina
contralateral nasal retina
Same side visual field!
Where do secondary neurons synapse in the optic tract
relay to the primary visual cortex (striate cortex) from the Lateral genticulate nucleus
Fibers from the lower quadrant visual fields travel in what to where
originate from the dorsomedial portion of the LGN
pass through the retrolenticular limb of internal capsule
travel through the parietal lobe (Baums loop)
target the superior bank of the calcarine sulcus on the cuneus gyrus
Fibers from the upper quadrant visual fields travel in what to where
originate in the ventrolateral portion of the LGN
pass into white matter of the temporal lobe called the meyers loop
Target the inferior bank of the calcarine sulcus on the lingual gyrus
Where does the macula represent
found in the middle of the LGN and will end up in the respective upper and lower quadrants but the information will be processed most posterior on the calcarine sulcus
Monocular blindness
lesion to one side of the optic nerve
Bitemporal heteronymous hemianopia
lesion at the optic chiasm
lose both nasal retinal layer fields
Ipsilateral right nasal hemianopia
lesion at the lateral aspect of the optic chiasm on the right side
lose the right temporal retina
Left homonymous hemianopia
lesion at the right optic tract
lose the left visual world for both eyes
Congruous
a deficit when the visual field loss of one eye can ve superimposed on that of the other eye (symmetrical)
Incongruous
a deficit where the visual field is not symmetrical among both eyes
Damage anterior to chiasm
affects the ipsilateral eye
damage at the chiasm
causes heteronymous deficits
damage posterior to the chiasm
causes homonymous defects
lesion to the posterior cerebral artery affects on the
still have the macula vision but have left homonymous hemianopia with macula sparring
