Radial and circular muscles are types of smooth muscle fibers that are present in different parts of the body, including the eye.
In the eye, the circular muscles are part of the ciliary body, which is a ring-shaped structure that surrounds the lens and helps to change its shape. The circular muscles, also known as the ciliary muscles, are arranged in a ring around the lens and contract to decrease the tension on the lens, allowing it to become more rounded for near vision.
The radial muscles, on the other hand, are located in the iris, which is the colored part of the eye that surrounds the pupil. The radial muscles, also known as the dilator muscles, are arranged in a spoke-like pattern and contract to dilate the pupil and allow more light to enter the eye.
Both the circular and radial muscles are controlled by the autonomic nervous system, which regulates involuntary functions in the body. The circular muscles are controlled by the parasympathetic nervous system, which causes them to contract and allows for near vision, while the radial muscles are controlled by the sympathetic nervous system, which causes them to contract and allows for dilation of the pupil in response to low light conditions.
Overall, the circular and radial muscles play important roles in the function of the eye, allowing for clear vision and adaptation to different lighting conditions.
