The Middle Layer of the Eye

Pupil

a circular opening in the center of the iris, and into the anterior chamber.

Iris

a thin diaphragm composed of connective tissue and smooth muscle fibers. It is the colored portion of the eye and lies between the cornea and the lens.

Circular set

act like a sphincter and contracts when stimulated by bright light making the pupil smaller.

Ciliary muscles

groups of muscle fibers

Anterior cavity

has two halves called the anterior chamber and the posterior chamber.

Ciliary processes

in the ciliary body, and has many folds.

The middle layer

includes the choroid coat, ciliary body, and the iris

Radial set

increases the pupil's diameter (dilates) in response to low levels of light allow more light to enter the eye.

Choroid coat

is loosely joined to the sclera and is honeycombed with blood vessels. It has many pigment-producing melanocytes. The melanin produced by these cells absorb excess light.

Suspensory ligaments

strong, delicate fibers that extend inward from the ciliary processes and holds the lens in position.

Aqueous humor

the epithelium on the inner surface of the ciliary body secretes a watery fluid. It helps nourish the structures in the anterior cavity of the eye and helps maintain the shape of the front of the eye.

Ciliary body

the thickest part of the middle layer, extends forward from the choroid coat and forms an internal ring around the front of the eye.