The Eyeball Anatomy Flashcards
what are the 3 layers of the eyeball
fibrous
vascular
inner
what 2 parts make up the fibrous layer
the sclera and the cornea
functions of the sclera and cornea
give shape and support to the eye
attachment site for extra-ocular muscles (sclera)
refracts light entering the eye (cornea)
what 3 parts make up the vascular layer (aka the urea)
Choroid
Ciliary body
Iris
what is the choroid
a layer of connective tissue and blood vessels which surrounds the outside of the eye
provides nourishment for the outer layers of the retina
site of nutrition and gas exchange
what is the ciliary body
the ciliary muscle and the ciliary processes - encircles the lens
ciliary muscles - smooth muscle fibres
ciliary processes - attach the lens to the ciliary body via zonula fibres
function of the ciliary body
changes the shape of the lens (accommodation)
secretes aqueous humour
what happens to the lens when the ciliary muscle is relaxed
the suspensory ligaments are taut
the lens is therefor stretched out and thin to help with distant vision
what happens to the lens when the ciliary muscle is contracted
the suspensory ligaments relax
the lens goes back to being pump and circular - thick and focussed to help with close vision
what is the iris
a circular structure an open space in the middle - the pupil
vascular and gives eye colour
controls the size of the pupil
how does the iris control the size of the pupil
The spinchter papillae muscle (parasympathetic) shrinks the pupil in response to light
the dilator papillae muscle (sympathetic) dilates the pupil in response to dark
what type of innervation is the dilator papillae muscle
sympathetic
‘fight or flight’ wide eye
what makes up the inner layer of the eye
the retina - this is the light detecting part
what are the 2 layers of the retina
neural layer
-consists of photoreceptors
pigmented layer
- underneath neural layer - attached to choroid layer
- supports neural layer
what is the non-visual retinal
anterior part of the eye where the pigmented layer continuous but the neural layer does not
what is the optic part of the retina
posteriorly and at the sides where both layers of the retina are present (seen in fundoscopy)
what is the centre of the Retina
the MACULA
what is in the macula
v pigmented
high concentration of CONES
responsible for high accuracy colour vision
what is the optic disc
area where the optic nerve and central retinal artery enter the Retina
had no light detecting cells - blind spot of the Retina
what vessel supplies the retina
central retinal artery
enters at the optic disc
branches views in ophthalmoscopy
where is the anterior chamber
between the cornea and the iris
what does the anterior chamber contain
aqueous humour
where is the posterior chamber
small chamber behind the iris and in front of the lens
what does the posterior chamber contain
aqueous humour
what connects the posterior and anterior chambers
pupillary opening
where is aqueous humour first secreted
into the posterior chamber - then transmitted to anterior chamber via the pupil
how is aqueous humour drained
via the trabecular meshwork into the canal of schlep
what happens if the drainage of aqueous humour is obstructed
pressure builds up leading to glaucoma - as the optic nerve can be damaged by the rise in pressure
what is the vitreous chamber
a chamber on the other side of the lens - it secretes vitreous humour and extends behind the lens to the retina
what is the centre of the macula
the fovea
