The eye is one of the smallest pieces of the human anatomy, yet is one of the most complex and amazing components of the human body. It appears to be simple, but is made up components that work well together to allow you do something very important, which is to see. In my years of study of biology and human anatomy, the structure of they eye has always amazed me.
The eye sits in orbits in the human skull also known as sockets, and is held in place and protected by tissue and muscle. The eye is also protected by other very small body parts including eyelids, eyebrows and eyelashes. All of these protect the eye from damage due to things such as dust and bright light.
The eye is made of numerous components including the following:
1) Cornea - Helps to maintain the shape of the anterior eyeball chamber. It is the front part of the eye and it also covers the iris and pupil. The cornea along with the lens (mentioned below) refracts light and in turn helps the eye to focus. The cornea is very sensitive to touch, light, and any chemical and the eyelid will do its best to protect the cornea from any of these.
2) Lens - The lens is located behind the iris and is used to focus light onto the retina. Its main function is to help allow the eye to focus on objects located at various distances. The process at focusing at distances is also known as accommodation.
3) Iris - Is a part of the retina which contains cone cells and is the colored part of the eye. These cone cells are used to help with resolution of vision. It is embedded with muscles that dilate and contract the pupil.
4) Pupil - Is a layer of thin epithelial cells that protects the cornea from damage. It is the black dot in the center of the iris that controls the amount of light that enters the eye.
5) Choroid - Is attached to the edges of the optic nerve and is located between the retina and sclera. It is only 0.5 mm thick and provides nourishment to the outer layers of the retina.
6) Sclera - The sclera is also known as the "white of the eye". It is composed of tough tissue that forms the eye's protective outer coat.
7) Aqueous Humor - Is the watery fluid that fills the space between the cornea and the iris. It serves two functions:
- Provides nutrients to the lens and corneal endothelium
- Provides pressure that maintains the convex shape
8) Fovea - Is responsible for sharp vision which is responsible for most day to day functions including reading and watching TV.
9) Optic Nerve - Is one of the most important components of the eye as it transmits visual information from the retina to the brain. It contains over 1.2 million nerve fibers.
These are some of the main components to the eye, all serving their own purpose. Each part depends on another part to work and ultimately allow the eye to serve its main purpose of vision.