Eye and Eye Movements Flashcards
Chronic infections in the ethmoid sinus can spread to what?
Orbits
What is an orbital blow out fracture? What does this cause? What are the symptoms?
Fracture of the orbital walls usually caused by indirect trauma; the blowout usually occurs medically and inferiorly involving the maxillary bone; orbital contents may prolapse and become entrapped in the maxillary sinus; symptoms include diplopia, globe ptosis, and exophthalmos (protrusion of the eyeball)
What movements of the eye occur along a vertical axis?
Abduction and adduction
What movements of the eye occur along a horizontal axis?
Elevation and depression
What movements of the eye occur along an anterior-posterior axis?
Intorsion (medial rotation) and extorsion (lateral rotation)
What is the innervation and action of the levator palpebrae superioris?
Innervation: superior branch of CN III
Action: elevates superior eyelid
What is the innervation and action of the superior oblique muscle?
Innervation: CN IV
Action: abducts, depresses, and medially rotates eye
What is the innervation and action of the inferior oblique muscle?
Innervation: inferior branch of CN III
Action: abducts, elevates, and laterally rotates the eye
What is the innervation and action of the superior rectus muscle?
Innervation: superior branch of CN III
Action: elevates, adducts, and medially rotates the eye
What is the innervation and action of the inferior rectus muscle?
Innervation: inferior branch of CN III
Action: depresses, adducts, and laterally rotates the eye
What is the innervation and action of the medial rectus muscle?
Innervation: inferior branch of CN III
Action: adducts eye
What is the innervation and action of the lateral rectus muscle?
Innervation: CN VI
Action: abducts eye
To discriminate muscle or nerve function from one another, the clinicians can trap one muscle and test its function pair. Muscles are trapped from performing their function when the visual gaze axis is _________________ to the muscle fiber direction
Perpendicular
How do you test the superior/inferior rectus muscles for elevation and depression, respectively?
Abduct using lateral rectus, then ask patient to look up/look down
How do you test the superior/inferior oblique muscles for depression and elevation, respectively?
Adduct the eye with medial rectus, then have the patient look down/look up
What nerves only pass through the superior orbital fissure?
Lacrimal nerve (V1), frontal nerve, and trochlear nerve (IV)
What nerves pass through both the superior orbital fissure and tendinous ring?
Oculomotor nerve superior and inferior divisions (III), nasociliary nerve, abducent nerve (VI)
What nerve only passes through the tendinous ring?
Optic nerve (II); passes through optic canal with opthalmic artery, which is within the tendinous ring
What muscles are under parasympathetic control?
Sphincter pupillae and ciliary muscle
What muscles are under sympathetic control?
Dilator pupillae and superior/inferior tarsal muscles
What synapses in the ciliary ganglion and what is just passing through?
Parasympathetic synapse here, but sensory and sympathetic fibers are just passing through
What is considered sensory in the eye?
Choroid, iris, and cornea
In the pupillary light reflex, what is sensory and what is motor?
Sensory: optic nerve (II)
Motor: parasympathetic to pupillary constrictor traveling with CN III
In the corneal reflex, what is sensory and what is motor?
Sensory: CN V (V1)
Motor: CN VII
What is in the fibrous layer of the eyeball?
Sclera and cornea
What is in the vascular layer of the eyeball?
Choroid, ciliary body, and iris
What is in the inner layer of the eyeball?
Retina
What is the palpebral conjunctiva?
Lines innermost part of eyelids
What is the bulbar (ocular) conjunctiva?
Lines outermost part of the eyeball
What artery and vein is found with the optic nerve?
Central retinal artery/vein
What muscle is affected in complete ptosis? What is wrong?
Levator palpebrae superioris; destruction of CN III or one of its branches that results in paralysis of LPS and complete ptosis
What muscle is affected in partial ptosis? What is wrong?
Tarsal muscle; probably Horner’s syndrome, which causes paralysis of the tarsal muscle
What causes papilledema?
Increased intracranial pressure; manifests as a bulging optic disc
Emergent situation and need to find the cause of the increased pressure
All the arteries of the eye come from what?
Internal carotid artery
What does the Supra-orbital artery connect to?
Superficial temporal artery
What does the supra-trochlear artery connect to?
Angular artery
What does the lacrimal artery connect to?
Middle meningeal artery
What does the ethmoidal arteries connect to?
Sphenopalatine artery
If there is a slow occlusion of the opthalmic artery, the anastomoses will send blood to the central retinal artery, but a blood clot or quick occlusion will cause what?
Blindness; no blood gets to central retinal artery
Where does the nasolacrimal duct drain to?
Inferior nasal meatus
What causes a central retinal vein occlusion?
Hardening of the CRA and hypertension in CRA can compress the CRV
What characterizes a central retinal vein occlusion?
Hemorrhages and dilated veins
What causes a central retinal artery occlusion?
Atherosclerosis and embolism
What characterizes a central retinal artery occlusion?
Retina appears white, cherry red spot, and veins/arteries attenuated
What is the anterior chamber?
Space between cornea and the iris/pupil
What is the posterior chamber?
Space between the iris/pupil and the lens and ciliary body
What is the ciliary body?
Circumferential tissue inside the eye composed of the ciliary muscle and ciliary processes
What is the ciliary processes?
Secrete aqueous humor which fills the anterior/posterior chambers
What happens when you block Schlemm’s Canal (scleral venous sinus)?
Increased pressure and glaucoma
What is a hyphema?
Rupture of arteries in anterior chamber
What does contraction of the ciliary muscles cause?
Decreases size of ciliary body, reduces tension on suspensory ligament, and the lens becomes more rounded (for near vision)