The Eye

Its function is to receive light by which an animal perceives and distinguishes objects in its immediate environment.

The eye is located in a socket in the skull called orbit which offers protection against physical damage.

Within the orbit there is a fatty layer lining which provides further protection as a shock absorber against mechanical injury.

In the socket, the eye is suspended by sets of muscles which move the eye.

Lateral rectus muscles move the eye left and right.

Superior and inferior rectus muscles move the eye up and down.

Oblique muscles steady the eye in it’s up and down movement.

In front of the eyeball, there are two thin folds of the skin, the eyelids, which protect the eye.

From the edge of the eyelids are many hairs called eyelashes which protect the eye from the entry of small foreign particles.

The eyebrows are raised portions of the skin above the eye, thickly covered with hair, whose function is to prevent sweat and dust from entering the eye.

In land vertebrates there is a lachrymal gland that continuously secretes a watery, saline and antiseptic fluid called tears.

The tears moisten the cornea and wash foreign particles out of the eye.

Functions of the External Structures of the Eye