|
Basic Anatomy & Function of the Eye:
Printable version
The Eye:
Being only about 1" wide, 1" deep and 0.9" tall, the eye is a compact and amazingly complex organ.
| The tough, outermost layer of the eye is called the
sclera
. This maintains the shape of the eye. The front part of this layer is clear and is called the
cornea
. All light must first pass through the cornea when it enters the eye. Attached to the sclera are six muscles that move the eye, called the
extraocular muscles
. |
|
the six extraocular muscles
|
-
Conjunctiva
Mucous membrane lining the inner surface of the eyelids and covering the front part of the sclera (white part of eye), responsible for keeping the eye moist.
-
Sclera
White part of the eye. Tough covering that (with the cornea ) forms the external, protective coat of the eye.
-
Cornea
Transparent tissue that forms the front part of the eyeball, covering the iris and pupil. The cornea is the first part of the eye that bends (or refract s) the light and provides most of the focusing power.
-
Iris
Actually classified as a muscle, the iris is the colored part of the eye in front of the crystalline lens that regulates the amount of light that enters the eye by adjusting the size of the pupil in the center.
-
Pupil
This is the black opening in the center of the eye where light enters. Pupil size changes when the iris
tenses or relaxes depending on the amount of light present.
-
Crystalline Lens
Double convex, transparent part of the eye, located behind the iris and in front of the vitreous body. Serves in conjunction with the cornea to refract incoming rays of light onto the retina .
-
Posterior capsule
This is a thin membrane that holds the crystalline lens in place.
-
Vitreous
This is the gel that fills the eye and allows it to maintain its shape. It also serves as a clear
pathway for light when it travels from the lens to the retina.
-
Macula
Yellow spot on the retina, where the photoreceptors are most
dense and responsible for the central vision. Has the
greatest concentration of cones, responsible for visual acuity and
the ability to see in color.
-
Retina
The retina is the nerve center of the eye where light is converted into an electrical signal that
travels to the brain. Cells, called rods and cones, within the retina transmit these signals along the
optic nerve, thereby enabling sight.
-
Optic Nerve
Bundle of nerve fibers that connect the retina with the brain. The optic nerve carries signals of light to the area of the brain called the visual cortex, which assembles the signals into images called vision.
|
