eye and orbit Flashcards
nn of the orbit
CN: 2,3,4,5,6
know foramen
cn II inn what at eye
special sensory of retina
cn 3 inn what at eye
sup, med, inf rectus, inf oblique and levator palpbrae superioris
motor inn
cn 4 inn what at eye
motor to sup oblique
cn 5 at eye
cutaneous sensory (v1 and v2)
cn6 at eye
lat rectus motor inn
basic mechanism of eye function
photons to the retina=photoreceptors
carried by optic nn to optic chiasm where crossover of lateral field occurs
R to L side of brain and vice versa
some visual info goes to other parts of the brain for processing and is used for head and eye movement coordination
label
label
lesion at optic chiasm
loss of lateral fields of view
label
white part of the eye
sclera
meningial coverings, CSF blockage?
meningial layers extend onto the optic nn until it reaches the eye
CSF blockage could impact the optic disc
choroid of the eye
vascular layer, supplies eye with nutrients
ciliary body
will pull on or relax the lens
contracts for near vision allowing lens to be compressed for focusing, zonular fiber are relaxed during this
iris
colored portions with two mm layers
outer longitudinal and inner circular
will constrict inner circular to constrict pupil(para from CN 3)
will constrict outer long to dialate (sym)
label
label
macula
region with the highest density of photoreceptors
usually avascular but surrounded by lots of vessels
levator palpbrae superioris action
elevates superior eyelid
superior oblique action
abducts
depresses
medial rotation
inferior oblique action
abduct
elevates
lat rotation
superior rectus action
elevates
adducts
medial rotation
inferior rectus action
depresses
adducts
lateral rotation
medial rectus action
adduction
lateral rectus action
abduction
sup oblique action explained
will rotate eye medially, down and abduct due to the trochlaer attatchment
ciliary ganglion contents and function
contains para/sym fibers
parasympathetics from CN III and sympathetics from the superior cervical ganglion
psotgang sympathetics but contains the synapse between pre and post gang para
will give branches that can hitch rides on CN V branches to go to the mm of the lens and pupil
allows for accomodated vision (change in lens size) and pupil size adjustment
pterygopalatine ganglion
pregang para from CN 7 (greater petrosal nn), postgang sym from the superior cervical ganglion
will provide branches to the nasal and lacrimal glands
submandibular ganglion
recieves parasym fiber (pregang) from CN7 (chroda tympani)
post gang sym from the superior cervical ganglion
control of salivary glands
otic ganglion
receives parasym from CN IX (pregang)
sym from sup cervical ganglion (postgang)
will provide ANS inn to the parotid gland
sympathetics of head/neck
can hitch rides on?
provided from the thoracolumbar distribution of sympathetic
synapses of pregang and postgang at the superior cervical gang
will then project postgang fibers to the ganglia of head/neck, hitch ride along the carotid Aa to reach this area
can then hitch rides on the branches of CN to reach targets
manifestations of loss of sympathetics to the head/neck
tosis=droppy eye lids
miosis=small pupil
anhidrosis=inability to sweat normally
Aa supply of the eye
int carotid will provide the opthalamic Aa this then branches to supply the eye lacrimal aa ant/post ethmoidal aa supratrochlear supraorbital ant/post ciliary (short/long) central Aa of retina dorsal nasal Aa zygomatic facial and temporal Aa
vitreous humor flow
from region of the greater arterial circle of iris to the scleral venous sinus
vv drainage of eye
sup/inf opthalamic vv drain to cavernous sinus, as well as supraorbital vv
infraorbital and angular drain to the pterygoid plexus
blowout fracture of the eye
possible with direct blow to break boen inferior to the orbit=herniation of adipose tissue but also mm
eye may not move properly
retinal detatchment
retina detatches from the choroid layer
can lead to blindness with cell death if not fixed
retinal detatchment
retina detatches from the choroid layer
can lead to blindness with cell death if not fixed
cataracts
clouded lens, fixed with artifical lens
glaucoma, kinds
obstruction to vitreous humor flow>usually out of the scleral venous plexus
can be open/closed angle
open: the trabecular mesh is blocked=increase in P which decreases blood flow to the eye and causes subsequent cell death
closed: increased P due to iris closure over trabecular meshwork=cannot drain, same result as open
hyphema
bleeding in the eye from trauma
CN 3 paralysis presentation
mm it inn will be out
does not inn the lat rectus or sup oblique, these are active and cause abduction, depression and medial rotation
also dialted pupil as there are no parasym to the ciliary gang from cn3
