GA: Eye + Eye Movements Flashcards
Look at the bones that make up the orbit
Where is there most likely to be breakage in an orbital blowout fracture?
Usually medially and inferiorly w/ the maxillary bone.
Orbital contents can prolapse and end up in the maxillary sinus
How are the eyeballs positioned within the skull?
medial walls of orbit = parallel
lateral walls = right angle to eachother
axes of gaze = parallel but axes of orbit diverage @ 45 degrees
What are the movements of the pupil?
normal primary postion = looking straight forward
What does the levator palpebrae superioris m. do + innervation?
Elevates superior eyelid (opens eye)
CN 3
What is the function + innervation of superior oblique M.?
ABducts + depresses + medially rotates
CN 4
What does inferior oblique M. do + innervation?
ABducts + elevates + laterally rotates eyeball
CN 3
Function + Innervation of Superior rectus M.
Elevates + ADduct + rotate medially
CN 3
Function + Innervation of Inferior rectus M.
Depresses + ADducts + rotates eyeball laterally
Function + Innervation of Medial Rectus
ADducts
CN 3
Function + Innervation of Lateral Rectus
ABducts
CN 6
Extraocular M.’s
What is the prime muscle mover for each of these directions?
What is the innervation of the orbit (sensory)?
V1 Opthalamic N. gives off 3 branches:
1) Frontal N. –> Supratrochlear + supraorbital N.’s
2) Lacrimal N.
3) Nasociliary N. –> Posterior ethmoidal N. + Anterior Ethmoidal N. + Infratrochlear N. + Long ciliary N. + Short ciliary N.
What is the innervation of the extraocular M.’s?
Oculomotor N. (IO, SR, IR, + LPS to open eye)
Trochlear N. (SO)
Abducent N. (LR)
How do the sympathetics infiltrate the eye and what do they make it do?
Sup. Cervical Ganglion –> Internal Carotid Plexus hitch
nasociliary = dilates eye
&
long ciliary = keeps eye open
A lesion of CN ____ causes trochlear palsy.
4 = SO
Heaad tilts away from affected side
A lesion of CN ____ causes abducens palsy.
6 = lateral rectus
Cannot look laterally w/ affected eye
What are the symptoms of oculomotor palsy?
Down + out eye
Complete ptosis
Pupil Dilation (loss of parasympathetics)
What should happen in the pupillary light reflex?
Both eyes should constrict
Light synapses in 4 nuclei:
- Pretectal
- Edinger-Westphal preganglionic nucleus
- Ciliary M.
- Constrictor pupillae M.
What should happen in the corneal reflex?
If the cornea detects touch or irritation is should close
CN V –> trigeminal nucleus, facial nucleus, facial N.
What are the layers of the eyeball:
- Fibrous
- Vascular
- Inner
Fibrous = sclera + cornea
Vascular = Choroid, Ciliary body, Iris
Inner = Retina
*optic nerve covered w/ all 3 layers of meninges*
What lines the innermost part of the eyelids?
Palpebral Conjunctiva
What lines the outermost part of the eyeball?
Bulbar (ocular) conjunctiva
What muscle is innervated by sympathetics and keeps the eyelid up?
Superior tarsal M.
What muscle helps open the eyelid and is inervated by CN 3?
Orbicularis oculi M.
What is this?
Subconjunctival hematoma
What is another word for pink eye?
Conjunctivitis
What muscle is affected in complete ptosis?
Levator Palpebrae Superioris
*Also can result from full destruction of CN 3 which opens the eye*
What muscle is affected in partial ptosis?
Tarsal muscle which is innervated by postganglionic sympathetic fibers
seen in horners syndrome
What causes papiledema?
Increased intracranial pressure
URGENT
Label these:
What happens if the central retinal artery is occuled?
You will end up blind. This is the only artery supplying the retina.
Anastomoses help w/ slow occlusions
Where does venous supply of the face drain?
1) Cavernous sinus
2) Pterygoid Venous plexus
What is occluded causing this appearence of “ketchup”?
Central Retinal Vein
What is occluded causing this “cherry red spot”?
Central Retinal Artery
What does the lacrimal appartus function in and what nerve innervates it?
Tear production
CN 7 via greater protrusal
How does tear production work?
- Greater petrosal N. + Deep Pretrosal form pterygoid canal
- Parasym. fibers synapse in pterygopalatine ganglion and travel w/ V2, then sygomatic branch, then lacrimal N. of V1
What are the 4 chambers of the eye?
- Ciliary body
- Ciliary Processes
- Anterior Chamber
- Posterior Chamber
How does the aqueous humor flow?
- Ciliary processes secrete aqueous humor into posterior chamber
- Flows through pupil to anterior chamber
- Drains into sclera venous sinus
- Humor is removed via limbial plexus
If you have a blockage of Schlemm’s canal (scleral venous sinus) what can happen?
Increased pressure and glaucoma
What is this?
Hyphema: rupture w/in the anterior chamber of the eye
When we need to use near vision like for reading what happens to our eye?
The ciliary muscles contract and this reduces the tension on the suspensory ligament, allowing the lens to become more rounded.
