Orbit Flashcards
what is the orbital axis
from center of cornea to retinal center
walls of the orbit
sup- frontal bone, lesser wing
lat- greater wing, zygomatic
inf- maxilla, zygomatic
med- body of sphenoid, lacrimal
what is the content of the optic cannal and where is located
located within the common tendinous ring\
optic nerve and opthalmic artery a
muscles that attach to the common tendinous ring
superior rectus
medial rectus
lateral rectus
inferior rectus
nerves that run thru the superior orbital fissue inside common tendinous ring
Occulomotor (sup+inf)
Nasocillary
-abducens
-optic
Nerves that run thru superior orbital fissure outside common tendinous ring
- frontal n
- lacrimal n
- trochlear n
The eye post is ivested in what and what is behind that
bulbar fascia with retrobulbar fascia behind it
what does the palpebral conjunctiva produce
produce fluid to lubricate the eyelid
what is the most sup muscle in the eye, inn
Levator palpebrae sup- elevates upper eyelid- styriated inn by CN3, smooth sympathetic
what are the 3 parts of the eye
- Capsul
- Nucleus
- Fundus
parts of the capsul
- sclera- external layer
- Cornea
- Choroid- supply of blood/nutrients
- ciliary body- on either side of lens
- retina
Parts of the nucleus
- lens- can change shape
2. vitrous body
Parts of fundus
- Optic disk and fovea
What does vit A deficiancy cause
deficiency of photpigments required for night vision
what part of the eye does a visual acuity test test
macular function (fovea)
what is the light reflex and what muscles do it
sphincter pupilae muscles are inn by parasympathetic n that constrict the eye and dialater pupilae dialate eye inn by sympathetic
Light relex test and what does it indicate (for same eye and other eye)
normal- both pupils constrict
same eye fails to constrict- indicates optic n injury
other eye fails to constrict- loss of CN3
What is the accomodation reflex
with parasympathetic inn by cn3 the cillary m will contract and the lens contricts for near vision
-lose this after 40 ish due to lens losing elasticity
movements of the eye
Adduction/Abduction
Elevaton/depression
Extorsion/intortion
where does the sup oblique m run
on med portion of orbit and wraps around trochlea to attach on lat side
what does abscence of sympathetic supply to deep smooth muscles of levator palpebra superioris cause
drooping of eyelid
What muscles are used to look up to the right, straight to the right, down to the right
up to right- r- IO, l-SR
side- r- LR, left MR
down to right- r-SO, IR
What two muscles in the eye arnt inn by the occulomotor nerve CN3
lat rectus- Abducens CN6
sup oblique- Trochlear CN4 (r supplies l mm, vise versa)
What is lacrimal fluid stimed by
parasympathetic inpulses from CN7
what is the most sup muscle in the orbit
levator palp sup
what are the branches of the opthalmic a and what branch enters the eye
Medial, central and lateral
central renial artery enters eye thru optic disk
indications of CN3 palsy
- ipsilateral drooping due to partial iacactivation of lev pal sup
- downward, abducted eye due to unopposed action of sup oblique+lat rectus
- dialation of ipsilateral pupil
- inability to accommodate ipsilateral eye
- diplopia
indications of CN6 abducens palsy
medial deviation due to unopposed action of medial rectus (causes double vision)
indication of CN4 trochlear n lesion and when would it get better
would cause r eye to be extorted and slightly elevated
-if they tilded their head to the unaffected side
where could tumor affect the CN2
thru sup orbital fissure
why does glacoma occur
due to increased intraocular pressur due to blockage of aquages bumor outflow thru scleral venous sinus
