Human Body

Nerves and Senses

What are the parts of the eye and their functions?

The major parts of the eye and their functions are summarized in the following chart:

Structure Function
Sclera Maintains shape of eye; protects eyeball; site of eye muscle attachment
Cornea Refracts incoming light; focuses light on the retina
Pupil Admits light
Iris Regulates amount of incoming light
Lens Refracts and focuses light rays
Aqueous humor Helps maintain shape of eye; maintains introcular pressure; nourishes and cushions cornea and lens
Ciliary body Holds lens in place; changes shape of lens
Vitreous humor Maintains intraocular pressure; transmits light to retina; keeps retina firmly pressed against choroids
Retina Absorbs light; stores vitamin A; forms impulses that are transmitted to brain
Optic nerve Transmits impulses to the brain
Choroid Absorbs stray light; nourishes retina

The accessory structures of the eye include the eyebrows, eyelids, eyelashes, conjunctiva, and lacrimal apparatus. These structures have several functions including protecting the anterior portion of the eye, preventing the entry of foreign particles, and keeping the eyeball moist.


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