Orbits & Eyes Flashcards
What is a blow out fracture of orbit? How and what is fractured? what does patient report?
trauma
fracture to ethmoid or lacrimal bone with entrapment of ocular muscles = double vision
What bones make the medial wall of orbit?
Maxilla
lacrimal
ethmoid
body of sphenoid
What bones make the lateral wall of orbit?
zygomatic
greater wing sphenoid
What bones make the floor of orbit?
maxilla
zygomatic
What bones make the roof of orbit?
frontal
lesser wing sphenoid
what are 3 layers to eye?
- sclera/cornea
- vascular
- neural
sclera means? How?
tough
predominantly collagen laid down in concentric circles
What attaches to sclera?
extraoccular eye muscles
What does the Cornea do?
principal refractor ~60%
5 layers of cornea?
- Epithelium (mucus membrane)
- Bowman’s layer
- stroma (collagen)
- Descemet’s membrane
- endothelium (cells don’t divide)
describe cornea histologically?
avascular
transparent
How is the cornea transparent?
very organized parallel collagen fibrils creating destructive interference
is the sclera transparent or opaque? why?
opaque
non ordered/non-uniform size of collagen
where is the anterior chamber?
between iris and cornea
what is the anterior chamber angle for?
aqueous humour drains out
Where in the anterior chamber angle does aqueous fluid drain out?
trabecular meshwork through the canal of Schlemm
What is the Uvea? 3 things
- Ciliary body (makes aqueous humour)
- chroid
- iris
3 things ciliary body does: which cells do what?
- make aqueous humour (epithelium)
- tethers lens (ciliary processes)
- accommodation (ciliary muscle)
How is intraocular pressure created?
via ciliary body making aquenous humour
What are zonules?
ligaments that attach ciliary processes to the lens.
what does the ciliary muscle do? describe it’s neural connections
focuses by changing lens shape
parasympathetic
smooth muscle
where do you find the ciliary muscle?
within ciliary body
what is presbyopia?
loss of lens accommodation/flexibility with age
2 muscles what control pupil: how innervated?
- sphincter pupilae, ParaS, CNIII
2. dilator pupilae, Symp
What is the choroid?
3 layers of blood vessels under the retina that keeps it alive
what is the most important layer of choroid?
choriocapillaris just underneath retina
What is the fovea?
highest area of concentrated cones, no rods, HIGH visual acuity
what is the macula?
area around fovea with decreased vasculature, mostly from choroid
what is the orra serrata?
junction between retina and ciliary body
what is the lamina cribosa?
a structure continuous with the sclera that runs perpendicular and through the optic nerve, contains sieve-holes that transmit nerve fibres
where are the retinal artery and vein located?
in or along the optic nerve
curtain come down over someone’s vision is most likely?
arterial ischemia/occlusion of central retinal artery
what are the vessels you see in the fundoscope?
central retinal artery
3 ciliary arteries are?
long posterior
short posterior
anterior ciliary
What are the 2 arteries what supply the retina?
- Central retinal artery: inner
2. posterior ciliary: outer
2 Muscles of the orbits and their innervation?
- orbicularis oculi (CNVII)
- levator palpebrae superiosis (CNIII)
They work in opposition
