What Is the Ciliary Muscle?

Also known as the ciliary ligament. The fiber bundles of the ciliary body muscles located on the inner surface of the anterior sclera and in the upper choroid space are the main components of the ciliary body and are smooth muscles. In the brown-black layer of the sclera, the front is attached to the scleral process, and the outer side of the back is connected to the inner layer of the sclera by means of many small plates. Below the sagittal section is a right-angled triangle, the hypotenuse is parallel to the sclera, the right angle is inwardly facing the ciliary process, and the tip points to the choroid, which is equivalent to the tip of all ciliary bodies. The ciliary muscle is composed of three kinds of fibers, the meridian fibers arranged side by side on the outer side; the annular fibers parallel to the limbus on the inner side; the radial fibers that are oblique and fan-shaped between the meridian fibers and the annular fibers. These muscle fibers each have special physiological functions.

Also known as the ciliary ligament. The fiber bundles of the ciliary body muscles located on the inner surface of the anterior sclera and in the upper choroid space are the main components of the ciliary body and are smooth muscles. In the brown-black layer of the sclera, the front is attached to the scleral process, and the outer side of the back is connected to the inner layer of the sclera by means of many small plates. Below the sagittal section is a right-angled triangle, the hypotenuse is parallel to the sclera, the right angle is inwardly facing the ciliary process, and the tip points to the choroid, which is equivalent to the tip of all ciliary bodies. The ciliary muscle is composed of three kinds of fibers, the meridian fibers arranged side by side on the outer side; the annular fibers parallel to the limbus on the inner side; the radial fibers that are oblique and fan-shaped between the meridian fibers and the annular fibers. These muscle fibers each have special physiological functions.

Chinese name

Ciliary muscle

lie in

Circular smooth muscles inside the eyes

Function

Is to change the shape of the lens

Make up

Composed of smooth muscle fiber bundles

The root cause of myopia

Lack of exercise for the ciliary muscle

Anatomy of the ciliary muscle

The ciliary muscles are smooth muscles, and there are three types of longitudinal fibers, annular fibers, and radial fibers according to the direction of the muscle fibers. Longitudinal fibers are at the outermost side, starting from the front of the choroid and ending at the sclera at the edge of the cornea. When contracted, the sclera sinus can be opened to promote aqueous humor circulation. The ring-shaped fiber is on the inside and surrounds the free edge of the ciliary body. When contracted, the lens can relax the ligament, increase the curvature of the lens, and adjust the eye's vision. If you often work for a long time and close distance, it can cause excessive tension in the ciliary muscles in a state of spasm, increase the curvature of the lens, fail to return to its original state, and cause pseudo myopia. Therefore, we should not spend too much time reading and writing. We should take appropriate rest, do eye exercises, or look at the distance for a while to relax the ciliary muscles to prevent myopia. Radiation fiber is located between the above two muscles and starts from the front of the longitudinally moving fiber. The fiber is connected in a fan shape inward to the annular fiber.

The ciliary muscle constitutes a complex muscular system, but the source of its tissue is still inconclusive. It is generally considered that the ciliary muscle is mainly composed of three groups: the longitudinally arranged muscle fibers in the outermost layer; the radial or oblique muscle fibers in the middle layer; the innermost annular muscle fibers. These three parts are connected to each other, and when the muscles contract, a three-dimensional forward and inward movement will occur. The ciliary muscle originates from the scleral process and the trabecular meshwork. The longitudinally aligned muscle fibers originate from the outer layer of the scleral process and the trabeculae of the cornea. Radial muscle fibers with inner collagen fibers and inner ring muscle fibers also originate from the columnar structure of the corneal sclera and trabecular meshwork. The ring structure formed by the scleral process can resist the collapse of the Schlemm's canal caused by the ciliary muscle pulling the trabecular columnar structure when the eye adjusts. The muscle fibers start with two heads, and then gradually close together to form a V shape. After the merger, the muscle fibers continue to extend from front to back. In the three-layer muscle, the V-shaped included angle of the longitudinal muscle fibers is an acute angle; the V-shaped included angle of the middle radial muscle fiber is wider; and the V-shaped included angle of the inner circular muscle is an obtuse angle. So the circular muscle looks like a circular plane.

Larger muscle bundles are located in the front 2/3 of the ciliary body, and a smaller amount of muscle fibers reaches the serrated margin backwards. The main function of the ciliary muscle is to shift the front 2/3 of the ciliary body forward and inward, and the other part is to move the front end of the choroid along the inner surface of the sclera to move forward and backward.

Under the electron microscope, the ciliary muscle is basically the same as the smooth muscle structure of other parts of the body, but there are still some differences. The muscle fibers outside each bundle are not collagen fibers, but are covered by a shell formed by flat fibroblasts. Each of the muscle fibers is surrounded by a continuous basement membrane. At the same time, there are many vesicles in the serous membrane, and each muscle fiber is filled with actin microfilaments with a diameter of 60 to 70 m. Accompanied by microfilaments, electrons are densely concentrated near the serous membrane. The above features are the main points for the diagnosis of smooth muscle tumors with ultra-microstructure. Mitochondria, endoplasmic reticulum and Golgi apparatus in the cytoplasm of ciliary muscle cells are more developed than smooth muscle cells in other parts. Ishikawa confirmed that there are three types of neuromuscular coupling in the smooth muscles here. Most of the synaptic ends have indirect contact with the septum basement membrane, which is similar to the neuromuscular coupling of the uterine and arterial walls. Many direct contact coupling methods.

In the connective tissue between muscle fiber bundles, nerves, collagen fibers and a small amount of pigment cells, fine particulate matter, and capillaries without window holes can be seen. However, in young people, there is less connective tissue between these muscle bundles. With the increase of age, especially since the age of 30, the connective tissue there has increased significantly and thickened, including the accumulation of collagen and particulate matter and vitreous changes. .