The eye is a complex sensory organ specialized in collecting visual information. The eye is composed of three main parts: eyeball (globe), orbit (eye socket), accessory structures (annexes). Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original EssayAccessory Structure The accessory structures of the eye include the eyelids, conjunctiva, caruncle, and lacrimal glands. The eyelids are folds of skin that cover and protect the eye. It contains glands that produce an oily secretion which in turn covers the tear layer and prevents tears from evaporating and the eyelids from adhering. The conjunctiva is a transparent mucous membrane that lines the inner surface of the eyelids and the outer surface of the eye. The conjunctiva secretes mucus to lubricate the eyeball and keep it moist. The caruncle is the small pink portion of the innermost corner of the eye that contains sebaceous glands, sweat glands and conjunctival tissue. The lacrimal gland (lacrimal gland) is located in the upper outer corner of each eye. The lacrimal gland secretes tears to keep the surface of the eye and the lining of the eyelids moist and lubricated. Tears help reduce friction, remove dust and debris from the eye, and prevent infections. Orbit (eye socket) The orbit (eye socket) is made up of the bone formed by the skull that contains the eyeball and connective tissues. Bones and connective tissues cushion and protect the eye. Muscles attached to the eyeball make it move in different directions. The eyeball The eyeball (globe) is rich in blood vessels. Human eyes are roughly spherical, filled with a clear, gel-like substance called vitreous humor. Supports internal structures and maintains the shape of the eye. Please note: this is just an example. Get a custom paper from our expert writers now. Get a custom essay The eyeball is made up of three concentric layers (tunic), whose names reflect their fundamental functions: a fibrous tunic, made up of the sclera posteriorly and the cornea anteriorly; a pigmented vascular tunic, including the choroid, the ciliary body and the iris; and a nervous tunic, the retina.