How many parts comprise the middle tunic of the eye?

The middle tunic of the eye, also referred to as the uvea or uveal layer, is composed of three distinct parts: the iris, the ciliary body, and the choroid. Each of these components plays a vital role in the overall function of the eye.

The iris is the colored part of the eye that regulates the size of the pupil and thus controls the amount of light that enters the eye. The ciliary body is responsible for producing aqueous humor and contains the ciliary muscle, which adjusts the lens for focusing. The choroid is a layer rich in blood vessels that provides nourishment to the retina and absorbs excess light to prevent scattering within the eye.

Understanding these three parts allows for insights into how the eye functions in terms of vision and the processing of light, making the knowledge of the middle tunic essential for grasping the anatomy and physiology of the eye.