Eye & Accessory Visual Structures

Description

The eye refers to the organ of vision and is composed of the eyeball and optic nerve. The eyeball itself is contained within a bony cavity, the orbit, which is made up of a number of bones from the facial skeleton. The orbital region overlies the orbit and contains the upper and lower eyelids and lacrimal apparatus. These structures control the exposure of the anterior eyeball to the external environment and lubricate it, respectively. Additionally, the orbital cavity contains accessory visual structures, including the extraocular muscles, which position the eyeball; nerves and vessels that supply the eyeball and its accessory structures; and the conjunctiva, a mucous membrane lining the anterior aspect of the eyeball and posterior aspects of the eyelids.