The choroid, responsible for accommodation, adaptation and nutrition of the retina, is a very important part of the structure of the eyeball. It consists of several parts, one of which is the ciliary (ciliary) body. It consists of many vessels and cells, the structure of which is characteristic of smooth muscle tissues.
Such cells are arranged in layers, and each of them has its own direction. Due to this, the necessary functionality of the ciliary body is achieved, which consists in maintaining continuous nutrition of its own muscle fibers and ensuring the ability of the eye to focus at different distances (accommodation). Another important function of the formation in question is the stabilization and maintenance of the necessary pressure inside the eyeball.
The structure of the eye: anatomy
So what is the named part of the choroid, and what are its functions? To understand, you need to consider the structure of the eye. Anatomy distinguishes in the visual organ 4 mainingredients:
- The peripheral part, also called the perceiving (it includes the eyeball itself, the protective organs of the eye, adnexal organs and the muscular apparatus responsible for the movement of the eyeball).
- Pathways consisting of the optic nerve, junction and tract.
- Visual centers in the subcortex.
- Higher visual centers, which are located in the back of the cerebral cortex.
The eyeball is a very complex optical device, which is confirmed by the diagram of the eye below.
The main task of this organ is to transmit the correct picture to the optic nerve. And all the components of the eyeball are involved in this:
- cornea;
- anterior chamber of the eye;
- iris;
- pupil;
- crystalline lens;
- vitreous body;
- retina;
- sclera;
- choroid (in fact, the ciliary body of the eye is part of it).
It is located, as the diagram shows, between the sclera, iris and retina.
Ciliary body: structure and functions
From the point of view of anatomy, the described part of the eyeball is a closed ring-shaped figure behind the iris, under the sclera of the eye. This location, by the way, does not allow direct examination of the ciliary body.
Considering the structural structure of this formation, we can distinguish two of its components: ciliary and flat.
- The first one comes close to the jagged edge, and its width fluctuates around 4 mm.
- The second one, the ciliary one, reaches up to 2 mm in width. It is on it that there are special processes (ciliary or ciliary), which together represent the ciliary crown. They are directly involved in the formation of fluid inside the eye. This happens due to blood filtration in many blood vessels that literally penetrate each of the processes, which, by the way, have a lamellar shape.
Looking at the ciliary body at the cell level, you can see that it consists of two layers: mesodermal and neuroectodermal. The first consists of two types of tissues - connective and muscle. But neuroectodermal is limited to the presence of only epithelial cells, the presence of which is due to the spread of the latter from the layer of the retina.
It turns out a kind of layer cake, the layers in which are arranged as follows (from the deepest):
- muscle layer;
- vascular layer;
- basement membrane;
- pigmented epithelium;
- epithelium without pigment layer;
- internal seal.
Next, we will take a closer look at the main components of the ciliary body, which includes the scheme of the eye.
Muscle layer
This layer is characterized by the presence of several muscles running in different directions: longitudinal, radial and circular. Longitudinal orientation is distinguished by muscle fibers called Brücke muscles, andwhich are the outer part of the layer. Beneath them are Ivanov's radially directed muscles. And the closing ones are the circularly directed Muller muscles.
The main task of each layer is to participate in the process of ensuring the ability of the eye to see clearly at different distances (accommodation). It happens in the following way. The inner part of the ciliary body is connected with the outer part of the lens (its capsule) through the ciliary belt, which consists of a large number of the finest fibers. The task of this formation is to fix the lens in the desired position, as well as to assist the ciliary muscle during accommodation processes.
The fibers of the ciliary girdle, also called zonular, are divided into two types: anterior and posterior. The former are attached to the equatorial and anterior regions of the lens capsule, while the latter are attached to the equatorial and, respectively, posterior. Thanks to them, the tension and relaxation of the ciliary muscle is transferred to the lens sheath, and it becomes either more rounded or more elongated, which is the process of focusing the eye at a certain distance.
Vascular layer
The structure of this layer is not much different from the structure of the choroid, the continuation of which it is. The composition of the vascular layer includes for the most part veins of various sizes. This is due to the fact that most of the arteries of the eye are located next to the choroid and, oddly enough, in the ciliary body, but in its muscular part. It is from there that small arterial vessels enter the choroid.
Basal Membrane
This layer is also a continuation of the choroid. From the inside, it is covered with two types of epithelial cells: pigmented and non-pigmented. These types of cells are nothing more than a non-functioning part of the retina. Behind them is the boundary membrane, which is not only the final layer of the ciliary body, but also separates it from the vitreous body.
Physiological role of the ciliary body
There are several main functions of the ciliary body:
- Participation in accommodation processes due to the ability to change the shape of the lens capsule with the help of the muscle layer of the ciliary body. Accommodation provides fine adjustment within 5 diopters.
- Ensuring sufficient intraocular fluid, due to the fact that the ciliary body contains a large number of vessels and, as a result, has a good blood supply. Subsequently, through this fluid, the pressure necessary at a certain moment is exerted on other components of the eyeball.
- Maintaining the right pressure inside the eye, which is one of the conditions for ensuring clear and crisp vision.
- The vascular system involved in providing nutrition to the ciliary body also nourishes the retina.
- The ciliary body acts as a support for the iris.
Pathologies of the ciliary body
In medicine, diseases that affect the ciliary body are distinguished:
- Glaucoma. With this disease, thebalance between the synthesized intraocular fluid and its outflow.
- Iridocyclitis. It is characterized by the appearance of inflammatory processes in the ciliary body.
- Reduced pressure inside the eye, due to a decrease in the volume of fluid in it. This can lead to swelling of the layers of the epithelium.
- Neoplasms in the ciliary body. In some cases, they may be of poor quality.
- Various pathologies of a congenital nature.
When the first signs of a problem appear, it is necessary to undergo a special examination that allows you to see the ciliary body of the eye, find out what pathological processes begin in it, and, if necessary, prescribe treatment.
Result
Summing up, it should be said once again that the ciliary body, being a component of the choroid, is responsible for a number of important functions inside the eyeball. Among them are the normalization of pressure inside the eye and maintaining its balance, the synthesis of intraocular fluid, ensuring normal blood circulation in nearby tissues and, of course, participation in the process of accommodation. It should be remembered that diseases of the ciliary body will also affect the general state of human vision.
