The Eye Flashcards
what are the 3 openings into the orbit
superior orbital fissure
inferior orbital fissure
opti canal
what goes through the superior orbital fissure
occulomotor nerve, trochlea nerve, trigeminal (ophthalmic) and abducens
what are the weakest parts of the orbit and why are they the weakest
the medial wall and floor
this is because they have air cavities next to them instead of bone
what is an orbital blow out fracture
where trauma to the orbit causes a fracture of the floor of the orbit
what does an orbital blow out fracture result in
swelling, double vision, anaesthesia over the cheeks
why is there anaesthesia over the cheeks in a blow out fracture
as the intra-orbital nerve (trigeminal) runs through the floor of the orbit so is damaged
what would be seen on a CT/X ray in a blow out fracture
the fractured floor
blood in the maxially sinus
orbital contents in the maxially sinus
what are the 2 types of glands found in the eyelid
glands in the tarsal plates and glands at the hair follicles
what happens if the glands at the tarsal plates are blocked
you get a meibomian cyst
what happens if the glands at the eyelashes are blocked
you get a stye
what are the tarsal plates
the fibrous skeleton giving the eyelids firmness and shape
what is the orbital septum
it is a separation produced by the tarsal plates and tendon of levator palpebrae
what is pre-septal orbital cellulitis
infection in the pre-septal orbit (space between the tarsal plates and the eyelid fat)
what is post-septal cellulitis
infection the orbital cavity
what does the orbital septum prevent
infection spreading between the pre and post septal orbit
what are the complications of post-septal cellulitis
abscess
spreading to the cavernous sinus - this could then potentially spread to the brain
what does the lacrimal gland do
produce tears to keep the conjunctiva and cornea lubricated
where do tears drain
into the lacrimal punctum - this then goes through the lacrimal sac to the nasolacrimal duct
what does the conjunctiva do
produces a mucus covering to help lubrication
what makes up the outer layer of the eyeball
the sclera and cornea
what covers the sclera
conjunctiva
true or false: the conjunctiva covers the cornea
false
what is subconjunctival haemorrhage
where a blood vessel in the conjunctiva suddenly bursts
what makes up the middle layer of the eye
choroid, ciliary body and the iris
what innervates the ciliary body
parasympathetics of the oculomotor nerve
what happens when the ciliary body contracts
the 2 ciliary bodies come closer together (giving less pressure on the suspensory ligaments), this makes the lens fatter so light is refracted more
where is aqueous humour produced
by the ciliary bodies
how is aqueous humour circulated
once produced by the ciliary bodies it flows into the posterior and anterior chambers
it then drains through the iridocorneal angle to drain the canal of Schlemm and into the venous system
what is the inner layer of the eye
the retina
what is the arterial supply to the retina
ophthalmic branch of the internal carotid artery
where do the ophthalmic veins drain to
cavernous sinus
what nerve supplies sensation to the eye
(ophthalmic) trigeminal
what nerve supplies motor to the eye
occulomotor, trochlea, abducens
what nerve allows sensation to the eye
optic
what us glaucoma
when the drainage of the aqueous humour is blocked causing an increase in intra-ocular pressure, damaging the optic nerve
when looking at far objects, what causes light to refract the most
the Cornea
describe the refraction of light when looking at close objects
the Cornea can’t refract light enough so the ciliary bodies contract to fatten the lens, allowing more refraction
what is the accommodation reflex
what occurs when looking at closer objects:
- pupils constrict
- eyes converge
- ciliary muscles contract
why do the eyes converge when looking at closer objects
to prevent too much light from entering
what is presbyopia
when the lens becomes stiffer so unable to refract light as well when looking at closer objects
what is cataracts
when the lens and cornea are no longer transparent so light isn’t let through
what is the purpose of the aqueous humour
supply nutrients and oxygen to the lens and cornea as these are avascular in order to remain translucent
what are the intrinsic muscles of the eye
- muscles of the iris (sphincter/dilator papillae)
- ciliary muscle
what are the 6 extra-ocular muscles controlling eye movement
inferior rectus, superior rectus, medial rectus, lateral rectus, superior oblique and inferior oblique
which of the extra-occular muscles are supplied by the trochlea nerve
superior oblique
which of the extra-occular muscles are supplied by abducens
lateral rectus
what are the functions of the extra ocular muscles
- medial/lateral rectus = allows medial/lateral movement
- inferior rectus = down and in
- superior rectus = up and in
- inferior oblique = up and out
- superior oblique = down and out
how do you test the superior oblique muscle
move eye medially and then down
how do you test the inferior oblique muscle
move eye medially and then down
how do you test the inferior rectus
move eye laterally and down
how do you test the superior rectus
move eye laterally and up
what will you see in occulomotor damage
pupil dilation
ptosis
eyes will go down and out
what will you see in trochlea damage
up and in
what will you see in abducens damage
eye will be pulled medially
what is uveitis
inflammation of the choroid layer in the eye
