Oc Anatomy Flashcards
which recti EOM inserts closest to the limbus?
where to all recti originate?
MR
SR–>LR–>IR–>MR (spiral of tillaux). 7.7-6.9-6.5-5.5
CTR (common tendinous ring) - aka annulus of Zinn
how many degrees toward midline for OBlique EOMs to have primary action? What is their primary action?
51-55 degrees
- action: TORSION (superiors intort, inferiors extort)
- OBlique: ABduct
Innervation for: SR? IR? IO? MR? LR? SO?
SR: SUPERIOR division of CN III
IR/IO/MR: INFERIOR division of CN III
LR: CN 6
SO: CN 4
LESSER wing of sphenoid - what wall of orbit? What runs thru it that’s important?
GREATER wing of sphenoid - what wall of orbit? What THREE foramen are in it, and what runs through them?
LESSER: SUPERIOR wall of orbit (ROOF=front-less) - OPTIC CANAL
GREATER: LATERAL wall of orbit (Lateral= Great-Z)
1) foramen rotundum (V2)
2) foramen ovale (V3), and lesser superficial petrosal
3) foramen spinosum (MMA)
most common benign orbital tumor in:
- adults?
- children?
adults: CAVERNOUS hemangioma
children: CAPILLARY hemangioma (strawberry birthmark)
The medial canthus is supplied by which arterial blood supply? Which artery did that blood supply terminate from?
ANGULAR artery; terminated from the FACIAL artery
The infraorbital artery is a branch of the ______ artery and supplies which two EOMs?
Maxillary; IO and IR
An internal carotid artery aneurysm within the cavernous sinus will most likely result in a CN___ palsy
6 - because it runs alongside the in the cavernous sinus
What’s the major threat to vision in a CRVO
Neovascular Glaucoma (90-day Glaucoma)
Venous DRAINAGE from the eye:
- central retinal vein drains _____
- ant ciliary veins drain ____
- vortex veins drain _____
- MAJORITY of draining occurs thru what vein?
- Where do the two branches of the inf. oph vein drain?
CRV: inner 6 layers of retina
ACV: anterior structures (CB, conj, schlemm’s canal, iris)
Vortex: choroid
-SUPERIOR oph vein - main drainage
-INF branches: inf branch –> pterygoid plexus, sup branch –> cavernous sinus
Two issues/syndromes d/t cavernous sinus problems? Sx/Signs of each
Tolosa Hunt Syndome - PAINFUL external ophthalmoplegia - inflammation of the SOF and/or cavernous
Carotid Cavernous Fistula (CCF) - PAINFUL d/t abnml comm b/w artery/vein w/i cavernous
Total corneal thickness?
Thickness of…
-Epi? (BM) -Bowman's? -Stroma? -Descemet's? -Endo?
550 microns
epi ~50 bowmans ~10 stroma ~450 descemet's ~10, increases throughout life endo ~5 (1 cell layer)
- TIGHT junction also termed what? Where’s the ONLY part of the cornea these exist? The iris?
- WEAK/loose jxn termed what? Where are these found in the cornea? The lens?
tight jxn = ZONULA occludens = surface layer of corneal EPI. Also seen in IRIS capillaries (Blood-aqueous-barrier)
weak/loose jxn = MACULA occludens = corneal ENDO (allows nutrients/AA/glucose thru since cornea is avascular). Also seen in LENS EPI
Collagen type:
- BM?
- Bowman’s?
- Stroma?
- Descemet’s?
- Lens capsule?
- Vitreous?
BM - Type 4 Bowmans - Type 1 Stroma - Type 1 Descemet's - Type 4 Lens capsule - Type 4 Vitreous - Type 2
-What layer of the epi secretes BM? Attaches via what cell type? What’s unique about this layer?
- BASAL layer - attaches via hemidesmosomes
- the ONLY mitotic layer in the epi
T/F: corneal innervation exists in all layers of the cornea
FALSE: ONLY in the MID stroma –> ANT stroma –> Bowman’s –> epi…anything behind the mid-stroma receives NO innervation
Which type of lens crystallin in lost with age? What is its normal role? Is it water or lipid-soluble?
ALPHA-crystallin - water soluble. Role: molecular chaperone–> helps beta and gamma crystallins recover from injury (prevents loss of lens fibers, maintains transparency) - LOSS of these fibers –> cataract
Potential dz of pts with:
BLUE sclera -
YELLOW sclera -
blue - O. imperfecta, Ehlers-Danlos, scleritis
yellow - old people (nml), alcoholism (liver dz), wilson dz (Kayser-Fleischer)
#1 cause of preseptal cellulitis? #1 cause of orbital cellulitis?
preseptal - minor skin trauma/hordeolum
-orbital - sinus infection
dacryoADENITIS - inflamm of lacrimal ___
dacryoCYSTITIS - inflamm of lacrimal ___ -
- two most common causes in adults?
- one most common cause in kids?
adenitis - lac gland
cystitis - lac sac
NLDO in adults: 1) involutional stenosis (closing w/ age), 2) sinusitis
NLDO in kids: 1) issue w/ valve of hasner (closed - usually prevents back flow)
What nerves pass THROUGH the SOF and the CTR?
What passes ABOVE the CTR?
THROUGH = NOA - nasociliary, oculomotor, abducens nerves
ABOVE = FLighT - frontal, lacrimal, trochlear nerves, +sup oph vein
BELOW = inf oph vein only
Three places the SNS “mooches”?
1) ICA
2) on CN3 to get to MULLER
3) on CN5 to get to iris DILATOR
what’s the most superior muscle in the orbit?
LEVATOR - not SR (it’s slightly below levator) - levator is just below the roof
the lacrimal gland lies within which bone?
FRONTAL
THINNEST bone in the orbit?
ethmoid (elms - makes up MEDIAL wall)
orbital cellulitis - infection of the ___ ___ **
lamina papyracea (thin orbital portion of the ethmoid bone)
GCA is an inflamm of ALL __ and __ -sized arteries, particularly the ____s, which leads to suffocation and irreverible ONH damage (___)
medium-large –> SPCAs (circle of Zinn) –> AAION
-will travel to contra eye if not tx’ed immediately w/ high dose corticosteroids
EXTERNAL jugular vein is formed by the ___ vein and the ___ ___ vein –> drains blood from ___ face
INTERNAL jugular is a continuation of the ___ sinus; drains blood from…..?
external = retromandibular + posterior auricular, drains SUPERFICIAL face
internal = cont. of SIGMOID sinus - drains all common stuff: facial, occipital, lingual, superior, medial thyroid veins
