Optic Nerve Flashcards
(35 cards)
how many myelinated axons make up the optic nerve
1.2 million
how long is the optic nerve
4cm
where does the intracanalicular portion travel through
the lesser wing of the sphenoid bone (with the ophthalmic artery)
what is the optic nerve called after it passes through the optic canal
intracranial portion
where is the myelin derived from that surrounds the ganglion cells within the optic nerve
oligodendrocytes
is the optic nerve prone to diseases that affect the central nervous system
yes
what are the 3 meningeal sheaths that surround the optic nerve
dura mater, arachnoid, and pia
what does the pia send into the optic nerve when it becomes the intraorbital portion
septa to support the nerve fiber bundles, artery, and vein
what happens to the optic nerve if IOP is elevated too high
cerebralspinal fluid in the subarachnoid space will exert pressure onto the nerve and cause the lamina cribrosa to bulge forward (convex)
where do the central artery and vein cross the subarachnoid space
12mm posterior to the globe
what may be a cause of papilledema during a funduscope exam
if intercranial pressure increased and compressed the central retinal vein
what are the 4 regions the optic nerve can be divided into
intraocular, orbital, intracanalicular, and intracranial
how long is the intraocular portion
1 mm
what is included in the intracocular portion
the optic disc and the portion of nerve that lies within the sclera
what is another term for the optic disc
the prelaminar zone
where is the cup situated within the disc
slightly off center, displaced temporally
what lines the optic cup
glial plaque or the central supporting tissue of Kuhnt or meniscus of Kuhnt
what is Bergmeister’s papilla
if the meniscus of Kuhnt is over-exaggerated during development
what is the meniscus of Kuhnt continuous with
a thinner membrane lining the surface of the nerve head, inner limiting membrane of Elschnig
what are the meniscus of Kuhnt and the inner limiting membrane of Elschnig composed of
astocytes
what is the inner limiting membrane of Elschnig continuous with peripherally
the basal footplates of the Muller cells
what do the central artery and vein share exiting the lamina cribrosa
a collagenous adventitial sheath that separates them from the nasal fibers of the optic nerve
how long is the intraorbital portion
25mm
how much does the optic nerve increase in size from the intraocular diameter to the intraorbital diameter
from 1.5mm to 3-4mm (due to myelin added)
