Lecture 1/5 Flashcards
list the 3 types of supportive cells of the retina
- mueller cells
- macroglia
- microglia
what are the fibular baskets of the mueller cells ?
they are extensions that go into receptive layer
describe the makeup of the ELM
it is a fusion of the cell walls in exact line of Mueller cells, cones, and rods
describe the makeup of the ILM
it is a fusion of the footplates of the Mueller cells
what is the largest cell in the retina?
Mueller cell
astrocytes are a type of
macroglia
astrocytes are associated with:
blood vessels and neurons
where are astrocytes found?
from the nerve fiber layer to the inner nuclear layer
what microglial cell is found in the retina?
wandering phagocytic cells
where are microglia found?
from nerve fiber layer to outer plexiform layer
the blood supply to the retina is from capillaries from what 2 places?
- central retinal artery (CRA)
- choriocapillaris
capillaries from the central retinal artery (CRA) supply what part of the retina?
- from nerve fiber layer to outer edge of inner nuclear layer
- inner half of the retina (primary and secondary neurons)
capillaries from the choriocapillaris supply what part of the retina?
outer half of the retina (rods and cones)
what locations are there tighter attachments at the retina?
- anterior at the ora serrata
- posterior at the optic nerve
- a small but weaker attachment at the macula
what causes the yellow color of the macula lutea?
a pigment called xenophyll
what is the diameter of the macula lutea?
5.5 mm diameter
the macula is relatively avascular. in what area is there no vessels?
the central 0.4 mm has no vessels
what is the diameter of the fovea centralis (central part of macula)?
1.5 mm in diameter
what is the floor of the fovea called and what does it not contain?
the foveola
-no blood vessels, no rods, no cones
the diameter of the foveola is
0.35 mm diameter
what is the very center of the foveola called?
the umbo (navel)
what are the sloping walls of the fovea called?
clivus
what is the inner ring of the fovea called and how wide is it?
inner ring: parafovea
0.5 mm wide
what is the outer ring of the fovea called and how wide is it?
outer ring: perifovea
1.5 mm wide
what retinal layers are present at the foveola?
layers 1-5 and the ILM
what retinal layers are NOT present at the foveola?
layers 6, 7, 8, and 9
what is the layer called where the fibers are pushed and going horizontally instead of vertically?
fiber layer of Henley
what is the diameter of the optic nerve head?
1.5 mm
what is the excavation of the optic nerve head called and why is it important?
called the cup, a result of embryological development, important for C/D ratio and glaucoma diagnosis
what is unique about the ILM and the optic nerve head?
the ILM does not go over the optic nerve, instead there is a thin layer of astrocytes
what is the layer of astrocytes over the optic nerve called?
central meniscus of Kuhnt
what is the lamina cribrosa?
the bridges across the posterior scleral foramen
what is the purpose of the lamina cribrosa?
to allow the axons of the ganglion cells to exit out of the eye with perforations and holes for the axons
what is the anterior portion of the lamina cribrosa derived from?
derived from the choroid
-made up of astrocytes and elastic tissue
what is the posterior portion of the lamina cribrosa derived from?
derived from the sclera
-made up of collagen fibers and some astrocytes
where does myelination of the fibers occur?
at the lamina cribrosa
where is the thickest area of the retina?
optic nerve head
560 microns thick
where is the thinnest area of the retina?
ora serrata
100 microns thick
how thick is the foveola?
130 microns thick
what is the average thickness throughout the retina?
370 microns
what are the nerve fibers that travel from the macula called?
papillomacular bundle
what are the nerve fibers that travel from the superior/ inferior temporal retina called?
arcuate fibers
what are the nerve fibers that travel from the superior/ inferior nasal retina called?
radial fibers
what is the superior inferior demarcation line called?
horizontal raphe
how many axons does the optic nerve contain?
1.2 million axons
what is the extent of the optic nerve?
from the globe in the back of the eye to the optic chiasm
what is the length of the optic nerve?
500 mm long
diameter of the optic nerve
3-4 mm
what are the 3 meninges surrounding the optic nerve?
dura mater, arachnoid, pia matter
what is important about the subarachnoid space?
it contains the cerebrospinal fluid (CSF)
how would a space occupying lesion in the brain manifest ocularly?
a tumor, for example, could cause pressure in the CSF that is transmitted up the back of the eye and causes swelling of the optic nerve
what is the optic chiasm?
the crossing of the optic nerves (decussation)
how many of the optic nerve fibers will cross at the optic chiasm?
1.4 million fibers
what is the optic tract?
from the optic chiasm to the lateral geniculate body (LGB)
what is special about the LGB
it is the first synapse of the axons from the ganglion cell
