Internal Structure of the Eye Flashcards
Sclera
External covering of the eye.
Very tough and opaque.
Contains collagen fibres.
Protects and maintains structure of the eyeball.
Provides attachment for eye muscles.
Cornea
Transparent part of the sclera (over eyeball).
Curved surface acts as main structure for most of the refraction of light towards the retina.
Conjunctiva
A thin transparent layer of living cells.
Protects much of the cornea from damage.
Choroid
A layer of pigmented cells between the retina and sclera.
Rich in blood vessels supplying the retina.
Black pigment prevents internal reflection of light.
Ciliary body
At the junction of the sclera and cornea.
Contains connective tissue, blood vessels and muscle.
Ciliary muscle
Ring of circular muscle attached to suspensory ligaments.
Contraction and relaxation alters tension in the ligaments and controls shape of lens.
Suspensory ligament
Tough and flexible but do not stretch.
Joins ciliary muscle to lens.
Transfers tension in the wall of the eyeball to make the lens thinner.
Lens
Transparent biconvex structure which focuses light onto the retina.
Aqueous humour
Clear solution of salts secreted by the ciliary body filling the space between the cornea and lens.
Iris
Pigmented diaphragm of muscle (radial and circular).
Controls the amount of light entering the eye by altering the size of the pupil.
Pupil
Gap in the iris.
Allows light through to the centre of the eye and eventually the retina.
Vitreous humour
Clear semi-solid jelly between the lens and the back of the eye.
Maintains the shape of the back of the eyes and supports the lens.
Retina
Contains light sensitive cells (rods and cones).
Converts light into electrical impulses.
Fovea
The most sensitive part at the centre of the retina.
Contains only cones at high density to give good daylight colour vision.
Optic nerve
Bundle of sensory fibres.
Carries impulses from the rods and cones in the retina to optic centre of the brain.
