Eye and Ear Flashcards
How does the eye change with age
The lens of the eye becomes less flexible and less able to thicken and so less able to focus on nearby objects (presbyopia)
What is cataracts a result of
Disruption of lens protein organisation
What is glaucoma a result of
Visual field loss and increased intraocular pressure.
Disruption of aqueous humour flow is responsible for increased intraocular pressure
What is the cornea and sclera
Tough outer coat for protection. Extraocular mm attach to sclera
What does the choroid of the eye do
Vascular coat nourishes retina. Between sclera and retina
What does the vitreous humour of the eye do
Gel occupies majority of eyeball. Served as cushion and transmits light. Adherant to retina in some areas
What does the aqueous humour do and what is it produced by
Produced by ciliary process. Clear watery solution that provides nutrients to the cornea and lens. Passes through pupil from posterior to anterior chamber and drains into the venous sinus of the sclera (blockage causes glaucoma)
What components of the eye are involved in glaucoma
Damage to the optic nerve
Why does a blockage of the central artery of the retina cause blindness
Terminal branches of the central retinal arteries are the only blood supply to the retina
Which muscles are involved in closure of eyelids
Levator palpeerde superioris - responsible for elevating eyelid. Relaxation of this muscle causes closure of the eyelid
orbicularis oris - closes the eyelid tightly
Which muscle is responsible for shutting the eyelid tightly
Orbicularis oris
What is levator palpebrae superioris innervated by
Occulomotor nn
What is the orbicularis oris innervated by
Sympathetic nervous system
What is the ciliary body of the eye
Contains ciliary smooth muscle which alters shape of lens to focus the eye. Epithelium secretes aqueous humour to maintain ocular pressure
What is occulomotor palsy (CN III)
Pupil dilatation, ptosis, eye faces downward and outward due to unopposed action of superior oblique and lateral rectus
What is abducent palsy (CN VI)
Lateral rectus paralysed. Eye loses ability to move laterally
On forward gaze, eye swings medially due to lack of opposition from lateral rectus
Patient will experience diplopia (double vision)
blood supply of the eye
carotid artery –> ophthalmic artery
ophthalmic artery–> retinal artery, posterior cillary arteries [choroid+ anterior optic nn] , muscular arteries [EO mm]
posterior ciliary arteryes + muscular aa –> anterior ciliary arteries [ciliary body and iris]
venous drainage of eye
Veins of eyeball–> superior and inferior ophthalmic veins
–>into and through superior orbital fissure –> blood enters into cavernous sinus
Pathway of lacrimal fluid
1- Lacrimal gland in lacrimal gland fossa
2- produces lacrimal fluid
3- lacrimal ducts take fluid to conjunctival sac
4- fluid goes to lacrimal lake. Then drained by lacrimal puncta to lacrimal sac
5- fluid goes to nasal cavity through nano-lacrimal duct
role of lacrimal gland
secrete lacrimal fluid
Role of lacrimal ducts
convey lacrimal fluid to conjunctival sac
Role of lacrimal puncta
Convey lacrimal fluid from the lacrimal lake to the nasolacirmal duct
Origin of the levator palpebrae superioris
Insertion
Sphenoid bone (lesser wing)
Superior eyelid
Innervation and action of levator palpebrae superioris
CNIII - deep layer supplied by sympathetic fibres
Elevates superior eyelid
What muscles are involved in pupil constriction and dilatation
Their innervation?
Constriction- sphincter pupillae (occulomotor nn)
Dilatation- dilator pupillae (SNS)
What effect does occulomotor palsy have
Pupil is dilated due to the unopposed actin of dilator pupillae- innervated by SNS
What passes through the superior orbital fissure
Conveys all nn except the optic, infraorbital nn
Has superior ophthalmic vein
What passes through the inferior orbital fissure
Conveys infraorbital nn and inferior ophthalmic vv
What cells are in high concentration in the macula
Cone cells (they see high quality vision and colour
What is an ipsilateral light reflex
Same eye you shine light in constricts
What is a contralateral light reflex
Other eye constricts even though you shine a light in the other
What is the corneal reflex
Put cotton bud in eye. Involuntary blinking of the eyelids because of stimulation of cornea
What is the accommodation reflex
Watching an object as it approaches eye
-Change in vergence, lens shape, accommodation and pupil shape
acronym for remembering innervations of extra ocular mm
LR6 SO4 AO3
[Lateral rectus 6, superior oblique 4, all others 3]
What is the effect of a lesion or compression of the optic chiasm (such as a pituitary tumour)
will stop transmission of nasal fibre signal hence only temporal halves will be seen (bilateral hemianopia)
What is the effect of a unilateral lesion posterior to optic chiasm
Hemianopia on the opposite side
How do you test muscle medial rectus
Adduct beyond midline (follow ring finger as you adduct eye beyond midline)
How do you test muscle superior rectus
Abduct then elevate
How do you test muscle inferior rectus
Abduct then depress
How do you test inferior oblique
Adduct then elevate
How do you test superior oblique
Adduct then depress
How do you test lateral rectus
abduct
What is damage of CN3
Ptosis of upper eyelid
Eyeball abducted and directed slightly inferiorly
What is damage of CN VI
Diplopia (double vision)
What is damage of CN VI
Medial deviation of affected eye
