Eye And Eye Movement (extra) Flashcards
How to test superior and inferior rectus ms.?
Abduct eye with lateral rectus m and raise/lower eye. Only SR m or IR m can work on eye if LR m abducts.
How to test superior oblique andingerior oblique ms.?
When eyes addicted by MR m, only SO m and IO m can work on eye.
Sensory innervation of the eye
Nasociliary n (V1) —> long ciliary n —> choroid, iris, cornea
SNS to the eye
Sympathetic root synapse in ciliary ganglion and travels to dilator papillae m and tarsal ms.
PSNS to eye
CN III synapses in ciliary ganglion with short ciliary n and acts on sphincter pupillae m and ciliary m/body
Trochlear palsy
Head tilts away from affected side. Double vision worse on looking down.
Abducens palsy
Cannot look laterally
Oculomotor palsy
Down and out eye
Complete ptosis
Pupillary dilation
Pupillary light reflex (4)
- Retinal cells of CN II sense light and synapse in protectable nucleus.
- Cells from pretectal nucleus synapse in Edinger-Westphal nucleus.
- Preganglionic cells synapse in ciliary ganglion.
- Postganglionic cells will innervate pupillary constrictor m.
Corneal reflex (3)
- Receptors in cornea detect irritant, travel in CN V, and synapse in trigeminal nucleus.
- Cells from trigeminal nucleus projects in facial nucleus.
- Facial n will cause eye to blink.
Fibrous layer of eye
Sclera and cornea
Vascular layer of eye
Choroid, ciliary body and iris
Inner layer of eye
Retina
Palpebrae conjunctiva
On inner eyelid
Bulbar conjunctiva
On outermost eye
Superior tarsal m.
Innervated by SNS. Partially closes eye. Partial ptosis is affected.
What muscle closes eyelid?
Orbicularis oculi m.
Venous drainage from eye into the cavernous sinus
Vortices veins drain into superior ophthalmic v and inferior ophthalmic v to cavernous sinus.
Venous drainage to Pterygoid plexus
Infraorbital v (from facial v) and from inferior ophthalmic v send a branch to pterygoid plexus
Tear production (3)
- Greater petrosal n (CN VII) and deep petrosal n become N of pterygoid canal.
- Will synapse in Pterygopalatine ganglion.
- Postganglionic fibers will travel on V2 (zygomatic branch) to a communicating branch then to lacrimal n (V1).
Lacrimal apparatus and drainage
Lacrimal gland makes tears. They drain into lacrimal canaliculi —> lacrimal sac —> nasolacrimal duct.
Flow of aqueous humor (4)
- Ciliary process secrete aqueous humor into posterior chamber.
- Flows thru pupil to anterior chamber (nourishes lens and cornea).
- Drains thru trabecular meshwork to sclera venous sinus.
- Humor removed by limbdal plexus.
Relationships of the sinuses to the orbit
Frontal sinuses superior
Maxillary sinuses inferior
Ethmoid sinuses medial
Sphenoid sinuses posterior
Orbital blow out fx
From indirect trauma.
Occurs medially and inferiorly involving maxillary bone.
Contents can be trapped in maxillary sinus.
Double vision, exophthalmos.
Angle of axis of orbit
45
Angle of the lateral walls of orbit
90
What axis is parallel?
Orbital axis (axes of gaze)
Intorsion vs extorsion
Intorsion (medial rotation)
Extorsion (lateral rotation)
Where do the rectus ms. originate?
Tendinous ring
Action of superior oblique m.
Abduct, depress and medially rotate eyeball
Action of inferior oblique m.
Abduct, elevate and laterally rotate eyeball
Action of inferior rectus m.
Depresses, adducts and laterally rotates eyeball
Action of superior rectus m.
Elevates, adducts and medially rotates eyeball
Adductors of eye
Medial rectus m.
Superior and inferior rectus ms.
Abductors of eye
Lateral rectus m.
Superior and inferior oblique ms.
Elevate eyes
SR m.
IO m.
Abduct and elevate
IO m.
Adduct and elevate
SR m.
Abduct and depress
SO m.
Adduct and depress
IR m.
Depress eyes
SO m.
IR m.
How to test the superior/inferior rectus ms. clinically:
Abduct eye, then have pt look up or down.
Can’t look up: SR m.
Cant’t look down: IR m.
How to test the superior/inferior oblique ms. clinically:
Adduct eye, then have pt look up or down.
Can’t look up: IO m.
Can’t look down: SO m.
Which nerves do NOT enter via the tendinous ring?
Lacrimal n.
Frontal n.
CN IV
What muscle keeps eyelid open?
Tarsal ms.
Central retinal v. occlusion
Hardening of CRA and HTN can compress the CRV.
Ketchup looking.
Central retinal a. occlusion
From atherosclerosis, embolism.
Retina is white. Cherry red spot.
Anterior chamber
Between cornea and iris/pupil
Posteriro chamber
Between iris pupil and lens/ciliary body
How does ciliary body assist in near vision?
Contracts ciliary ms. –> reduced tension on suspensory L.
Lens becomes rounder.
