Visual Pathway Anatomy Flashcards
The 7 major parts of the Visual Pathway
1) Retina
2) Optic Nerve
3) Optic Chiasm
4) Optic Tract
5) Lateral Geniculate Nucleus
6) Optic Radiations
7) Striate Cortex (visual cortex)
How many cells and synapses in the visual pathway? What are the cells?
5 cells, and 4 synapses (between the cells)
The 5 cells:
1) Recepetor cell in the retina (rod or cone)
2) Bipolar cell in the retina
3) ganglion cell in the retina
4) LGN neuron
5) Visual cortex neuron
what structures are the axons of the ganglion cells?
optic nerve, optic chiasm, optic tract
what structure is the axons of the LGN?
optic radiations
how long is the optic nerve?
5-6 cm
what are the sections of the optic nerve?
intraocular intraorbital intracanal (part that passes through optic canal) intracranial (from the optic canal to the optic chiasm)
what is the diameter of the optic nerve intraocularly and postlaminarly?
1.5 mm intraocularly, 3 mm postlaminarly
what does the lamina cribrosa have to do with the visual pathway?
it is the network of scleral fibers through which the optic nerve fibers exit the globe
describe the meningeal sheaths of the optic nerve
the optic nerve is sheathed in meningeal layers that correspond with, and are continuous with, the cerebral meningeal layers (dura, arachnoid, and pia)
how is the intraocular ON bundled?
into fascicles by astrocyte sheaths
how is the postlaminar ON bundled?
by an additional connective tissue sheath, and by oligodendrocyte myelination
what is the intermediary tissue (of Kuhnt)?
the ring of glial tissue that separates the ON fibers from the retinal layers
what is the border tissue (of Jacoby)?
a continuation of the the intermediary tissue of Kuhnt, which separates the ON fibers from the choroid
what is the border tissue (of Elschnig)?
a ring of collagenous tissue that lies outside of the glial sheaths of the ON
what is the clinical significance of the attachment of certain EOMs to the ON sheath? what is this condition called?
movement of the eyes may cause pain if the optic nerve is swollen (optic neuritis)
the ON is inferior to the _________ and the _________.
olfactory tract, anterior cerebral artery
the ON is lateral to the _________.
sphenoidal sinus
the ON is _________ to the olfactory tract and anterior cerebral artery.
inferior
which EOMs are attached to the ON sheath?
medial and superior recti
the ON is _________ to the sphenoidal sinus.
lateral
what supplies blood to the prelaminar and laminar ON?
unfenestrated peripapillary choroidal network
what is the function of the glial tissue network of the prelaminar ON?
it provides structural support for the delicate nerve fibers
what are the glial tissues of the prelaminar ON?
the intermediary tissue (of Kuhnt), the border tissue (of Jacoby), and the marginal/border tissue (of Elschnig)
what is a fenestrated capillary? unfenestrated?
a fenestrated capillary is one with small pores that allows small molecules and some proteins to diffuse through; unfenstrated do not have these pores, and so limit what passes through
what blood vessels supply the postlaminar portion of the ON?
opthalmic a.
central retinal a.
pial vessels
what blood vessels supply the intracranial ON?
opthalmic a.
anterior cerebral a.
anterior communicating a.
internal carotid a.
