Opt 114 visual pathway: optic nerve (composition/arrangement, myelination/papilla edema)

is the optic nerve a peripheral nerve

technically yes, but not a true peripheral nerve

what cranial nerve characteristics does the optic nerve have

extension of brain tract, myelinated by oligodendrocytes, covered by 3 layers of meninges

what would a true peripheral nerve be myelinated by

Schwann cells

does the optic nerve have a subarachnoid space

yes

what is found within the subarachnoid space

CSF

if the pressure in the subarachnoid space increases, what can happen

occlusion of veins, compression of nerve

what makes up the optic nerve

ganglion cell axons

the optic nerves join to form ___ which is found where

optic chiasm, found anterior to the pituitary gland

what portion of the optic disc is taken up by the macular fibers

temporal wedge

what portion of the optic disc is taken up by the superior temporal fibers

superior wedge

what portion of the optic disc is taken up by the inferior temporal fibers

inferior wedge

what portion of the optic disc is taken up by the superior nasal fibers

superior nasal wedge

what portion of the optic disc is taken up by the inferior nasal fibers

inferior nasal wedge

what portion of the optic nerve do the macular fibers travel in

center

what portion of the optic nerve do the superior temporal fibers travel in

superior temporal quadrant

what portion of the optic nerve do the inferior temporal fibers travel in

inferior temporal quadrant

what portion of the optic nerve do the superior nasal fibers travel in

superior nasal quadrant

what portion of the optic nerve do the inferior nasal fibers travel in

inferior nasal quadrant

if you see bright white around the optic disc, what do you think that is

myelination

is myelination of the optic disc usually seen around the whole disc

not often but it does happen, usually just one side

what can myelination of the optic nerve cause

larger blind spot, increase pressure, increase glaucoma, impact vein occlusions

if the optic nerve is inflamed, what will it impact

rectus muscles

why will it affect the rectus muscles if the optic nerve is inflamed

runs through the annulus of zinn (origination of rectus muscles)

why does pressure in the subarachnoid space cause compression of the nerve

dura won't give, so the nerve does instead

is the optic nerve centered in the annulus of zinn

no

where is the optic nerve located in the annulus of zinn

closer to the medial rectus

which rectus muscle will be impacted first with optic nerve inflammation

medial rectus

what is papilla edema

optic nerve swelling due to elevated CSF

what is the order of tests you would order if you suspect papilla edema

MRI, then lumbar puncture

what will papilla edema cause

compromised blood flow in the optic nerve

what does the optic nerve look like with papilla edema

round, red, not distinct

what is pseudopapilla edema

CSF isn't elevated but the nerve is still swollen

what is pseudopapilla edema usually associated with

young women over a certain BMI weight or using hormone birth control