Eye Flashcards
What is susceptible to compression and shear injury which leads to traumatic optic neuropathy?
Intracanalicular portion of II nerve
What can loss of innervation to LPS cause? what innervation was lost?
Levator palpebrae superioris m elevates upper eyelid. destruction of III or branches leads to paralysis and
COMPLETE PTOSIS
Loss of innervation to tarsal m causes what? What is the innervation to the tarsal m?
Loss causes slight ptosis
Usually occurs with Horner’s syndrome
Loss in post sympathetics going to this smooth m
What is the drainage pathway of the lacrimal gland? why does the nose run when crying?
Lacrimal glands drain into apex of superior fornix
Lacrimal caniculi collect tears ->lacrimal sac ->nasolacrimal duct ->inferior meatus (this connection is why nose runs when crying)
Which wall of the orbit is thin?
the medial wall with the 7 bones
Paper thin
What is the thicker wall of the orbit?
Lateral
What goes through the optic canal?
CNII and ophthalmic a
What goes through SOF?
CNII, IV, V1, and VI
ophthalmic v
What are the margins of the orbit?
supraorbital margin: frontal bone and has a foramen
Lateral margin: zygomatic bone and orbital tubercle
Infraorbital margin: zygomatic and maxilla bone
What is TON?
Traumatic optic neruopathy: forces applied to temporal, maxillary and frontal regions transmitted to optic canal
There is an Immediate or slowly progressive loss of vision ipsilateral
Head is commonly struck by blunt object
What is a blow out fracture?
Floor of orbit trauma due to trauma of front eyeball
Herniation of orbit contents into maxillary sinus
Also air can come out of sinus to go behind orbit and push out eye
What are the three Le Forte Maxillary fractures?
I: transverse fracture of maxillae above alveolar processes
II: pyramidal shaped, one orbit
III: both orbits, face separated from skull (Panda)
What is the main GSA to the eyeball?
nasociliary
What is the GSA to the eye?
lacrimal
What conveys GSA pain fibers to cornea?
long ciliary n
What does the central a supply?
4 quadrants of the retina through upper and lower temporal branches and upper and lower nasal branches
Anastomose: circle of Zinn-haller
What happens with lesion of the superior division of III?
complete ptosis - LPS
Superior rectus - inability to abduct and elevate eye
What nerve does an increase in intercranial pressure compress causing paralysis and eye to be medial?
abducens n: lateral rectus
What are not the cardinal signs of Gaze?
Looking up or down
What is oculomotor nerve palsy?
only mm working are SO and LR
Cant open eyes
eye is dilated
looking down and out
What is the parasympathetic pathway for innervation to the eye?
EWN->CN III GVE-p->ciliary ganglion ->sphincter pupillae m +ciliary m
pupillary constriction and thickening of lens for near vision
What is the sympathetic pathway for innervation of the eye?
SCG->ICN->sympathetic br to ciliary ganglion -> passes through ciliary ganglion->pupillary dilator and tarsal m
What is the direct and consensual corneal reflexes?
lightly touching of cornea->naked n endings in cornea->nasociliary afferents (long)->descending nucleus of V->facial nucleus ->VII (temporal) ->orbicularis oculi m -> blink both eyes
In by 5, out by 7
What is the direct light reflex?
Light->optic n->optic tract->branchium of superior colliculus ->superior colliculus ->pretectum->EWN->III->ciliary ganglion->pupillary const. mm ->ipsilateral constriction
What is the consensual light reflex?
on the ipsilateral side:
light->optic n->optic tract->branchium of superior colliculus->superior colliculus->pretectum->Posterior commissure
Now on contralateral side:
->EWN->III->ciliary ganglion->pupillary const mm->contralateral constriction
What is the pupillary dilation response?
Stimulus is decrease in light
retina->optic n->superior colliculus->pretectum->reticular formation->lateral reticulospinal tract->preganglionic sym ILCC at T1
->SCG->sympathetic branch to ciliary ganglion->pupillary dilator m
What can blockage of sinus venosus sclera cause?
build of of pressure due to aqueous humor and ->glaucoma
What are the signs of Horners syndrome?
Ptosis (SLIGHT), anhidrosis, and mitosis
There is a decrease in sympathetics
What type of response is accommodation?
cortically mediated response!
What are the three parts of accommodation?
I: convergence: medial recti mm
II: pupillary constriction - parasym through III
III: thickening of lens - focus on near
All parasympathetic responses
What can pituitary macroademona cause when it infiltrates cavernous sinus?
press on optic chiasm: peripheral vision loss
CN III, IV, VI
ICA compression
Where do cataracts form?
lens
What is argyll-roberston pupil?
syphilis infection
pupils unreactive to light
Pupils do constrict during accomodation
Destruction of pretectum
What is Holmes-Adie pupil?
benign due to lesion of ciliary ganglion
pupils unreactive to light
pupils do constrict during accommodation but take a LONG ASS TIME
common in young females
What does choroid damage cause?
autoimmune rejection of undamaged eye
called sympathetic ophthalamia
What divides the anterior chamber from the posterior chamber?
lens
What is hyphema?
damage to arterial circle of iris
blood in ant. chamber due to trauma
MEDICAL EMERGENCY
What is subconjuctival hemorrhage?
Damage to deep pericorneal plexus
bleeding restricted to subconjunctival tissue or bulbar fascia
What is conjuctivities?
involves superficial pericorneal plexus
brick-red inflammation/irritant of conjuctiva especially at fornices
vessels movable
redness doesnt fade
What is pailledema?
extension of subarachnoid space around optic n
increase in intercranial pressure restricts venous return from retina->edema or swelling of optic disc
may also disrupt retrograde axonal flow->proximal fibers swell
What are the clinical presentations of atherosclerosis of central retinal a?
abrupt painless blindness
cherry red macula
What is trigeminal neuralgia?
chronic pain, extreme sporadic sudden burning facial pain
describe meningeal dura
continuous with sheath of optic n and bulbar fascia
Describe bulbar fascia
covers optic n and entire eyeball except cornea
Where does the inferior ophthalmic v drain into?
plexus->cavernous sinus
