Ciliary body (ciliary body): structure and function. Eye diagram

24.05.2020

The choroid, which is responsible for accommodation, adaptation and nutrition of the retina, is a very important part of the structure eyeball... It consists of several parts, one of which is the 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. Thanks 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 education under consideration is stabilization and maintenance of the required pressure inside the eyeball.

Eye structure: anatomy

So what is the named part of the choroid, and what are its functions? To understand, you need to consider Anatomy distinguishes 4 main components in the visual organ:

The peripheral part, also called the perceiving part (it includes the eyeball itself, the protective organs of the eye, accessory 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.
The higher visual centers, which are located at the back of the cerebral cortex.

The eyeball is a very sophisticated optical device, which is confirmed by the eye diagram below.

The main task of the named organ is to transmit the correct picture optic nerve... And all the constituent parts of the eyeball are involved in this:

cornea;
anterior chamber of the eye;
iris;
pupil;
lens;
retina;
sclera;
choroid (in fact, the ciliary body of the eye is a part of it).

It is located, as the diagram shows, between the sclera, iris and retina.

Ciliary body: structure and function

From the anatomical point of view, the described part of the eyeball is a closed ring-shaped figure behind the iris, under the scleral.This location, by the way, does not allow direct examination of the ciliary body.

Considering the structural structure this education, there are 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, ciliary, reaches up to 2 mm in width. It is on it that special processes (ciliary or ciliary) are located, which together represent the ciliary crown. They are directly involved in the formation of fluid inside the eye. This happens due to the filtration of blood in a variety blood vessels, which literally penetrate each of the processes, which, by the way, have a lamellar shape.

Examining the ciliary body at the cell level, one 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 by the presence of only epithelial cells, the presence of which is due to the spread of the latter from the retinal layer.

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;
pigment epithelium;
epithelium without pigment layer;
inner seal diaphragm.

Muscle layer

This layer is characterized by the presence of several muscles running in different directions: longitudinal, radial and circular. Muscle fibers, called Brücke muscles, which are the outer part of the layer, differ in the longitudinal direction. Below them are the radially directed muscles of Ivanov. And the trailing muscles are the circularly directed Mueller muscles.

The main task of each layer is to participate in the process of ensuring the eye's ability to see clearly at different distances (accommodation). It happens as follows. The inner part of the ciliary body is connected with the outer part of the lens (its capsule) through the ciliary girdle, 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 accommodative 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, and the latter to the equatorial and, accordingly, posterior. Thanks to them, the tension and relaxation of the ciliary muscle is transferred to the shell of the lens, 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 vascular layer includes mostly veins of various sizes. This is due to the fact that most of arteries of the eye is 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.

Basement membrane

This layer is 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 the processes of accommodation, thanks to the ability to change the shape of the lens capsule with the help of the muscle layer of the ciliary body. The accommodation provides a fine adjustment within 5 diopters.
Providing a sufficient amount of 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 required 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 clear vision.
The vascular system, involved in providing nutrition to the ciliary body, nourishes and
The ciliary body acts as a support for the iris of the eye.

Ciliary body pathologies

In medicine, diseases that affect the ciliary body are distinguished:

Glaucoma. With this ailment, the balance between the synthesized intraocular fluid and its outflow is disturbed.
Iridocyclitis. It is characterized by the appearance 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 epithelial layers.
Neoplasms in the ciliary body. In some cases, they may be substandard.
Various pathologies of a congenital nature.

When the first signs of a problem appear, you must go through special examination, allowing you to see the ciliary body of the eye, find out what pathological processes begin in it, and, if necessary, prescribe treatment.

Outcome

Summing up, it should be said once again that the ciliary body, being a component of the choroid of the eye, is responsible for a number of important functions inside the eyeball. Among them are the normalization of pressure inside the eye and maintenance of its balance, the synthesis of intraocular fluid, the provision of 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 general condition human vision.

I had laser eye surgery ten years ago, but in last years my vision became significantly short-sighted. I consulted an ophthalmologist to see if it was eye strain because I work a lot on computers, or part of a natural deterioration in vision over time, or both. My ophthalmologist seems to think that in my case I am young enough, that the natural degradation with age is minimal, and that my main problem is eye strain. She believes that I can regain about 90% of my vision after surgery if I can reduce eye strain. She gave me a few eye dropsto help with dryness, and recommended different waysto help my eyes recover.

I decided to look at eye strain to learn more about what conditions are causing it and what can alleviate it. I learned that the eye needs to be flatter to accommodate focusing on far objects and rounded to focus on near objects. flat with spring connective tissuecalled choroidswhat it taught to pull. Attached to these vascular muscles are muscles called ciliary muscleswhich stretch the choroid as they contract. This action causes the choroid to stop pulling the lens and the lens returns to a more rounded shape. So when the ciliary muscles are relaxed, you can see far. When the ciliary muscles contract, you can see large This diagram from the York University website was the clearest explanation I've come across:

So the reason for my current inability to focus on distant objects is because focusing so much on close objects, mainly on computer monitors, strains my eyes. To regain the ability to focus on distant objects, I need to reduce the load and allow my muscles to relax. If they relax, the choroid can pull the gaze into a flatter shape, necessary to see far.

However, I cannot reconcile this model with how I understand the mechanics of other muscles in my body. If I go to the gym and run or lift weights, or in any way put my muscles to work, they respond by getting stronger without sacrificing ability Stop contracting. The muscles in my body do not lose the ability to relax, no matter how much I exercise them. I have never heard of anyone working too hard or too long to keep their biceps in a constant state of contraction.

In fact, in my experience, after a hard workout it is impossibleso that my muscles don't relax and resist doing more work. When I do my biceps in gym and I do this to the point that I can no longer lift the weight, my muscles give up and I lose weight. In the same way, if I spent a long time looking at close objects, should my ciliary muscles give up, allowing the vascular shell, making clear distance vision an inevitable result?

The idea that my ciliary muscles have to relax in order to see far is also contrary to my personal anecdotal experience. Sometimes I can see far, but I cannot hold it for longer than a few seconds. If I try to keep focus on distant objects for too long, in my I get an unpleasant feeling that is hard to describe, but it is a form of pain that makes me give up. My vision becomes blurry and I can only see close objects again. If my biceps worked the same way, it would hurt if my arm was hanging right with the load, and the only way to lighten it is to lift the weight, which doesn't make sense. I feel like the effort is to see far away and when I'm tired I can only see in close-up.

It’s not that I think that in all medical research of the eye this is backwards, but that there is an aspect that I don’t see (pun intended).

How can it be that the ciliary muscles, unlike other muscles, lose their ability to relax?

Why aren't my ciliary muscles depleted and allowing the choroid to be conquered?

When it comes to focusing on distant subjects - perhaps it has nothing to do with distance? I think you would "gaze" at objects with intense concentration rather than gaze casually, and you could probably flicker less and move less in the direction of your gaze, fatiguing the retina. - Superbest Apr 21 14 2014-04-21 20:49:22

To relax your eye muscles and prevent eye strain, you can follow the 20-20-20 rule of looking at something at least 20 feet every 20 minutes for at least 20 seconds. This should work for problems that are at least not pathological, but I'm not an expert, so take the advice with a grain of salt (the rule is sound, but the later half of my answer is just my opinion). - user13129 15 2015-01-21 06:22:50

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First of all, I must correct some points that have been misunderstood. Do not change the question because it will lead to confusion.

"The way the lens is flattened is the use of springy connective tissue called the choroid to pull it."

In classical ophthalmology, you do not need to think about the choroid in direct relation to placement: the choroid is a spongy layer between the sclera and the retina and, in general, consists of blood vessels. The anterior part of the choroid continues forward to become the ciliary body, which in turn contains the ciliary muscle - one circular muscle per eye. From the ciliary body / muscle proliferation of the zonule (fibers of the zonule) and these are fixed at the equator of the lens.

physiology: contraction ciliary muscle causes ciliary ligamentsto loosen and steel "Free" lensto bulge and move focus to the front ( not vascular itself contracts). If the ciliary muscle relaxes, then the zones tighten, and therefore the lens becomes flatter (less convex), moving the focus back. In other words, you can say it in terms of depth of focus - a convex lens gives less depth, less convex gives more depth of focus.

So the classic layer of choroid does nothing (look at the link related to choroid - almost nothing is said about placement).

A “constant state of contraction” can be physiological (\u003d normal) as well as abnormal, and this is very common in some conditions (muscle spasms). One example is priapism, where the contraction of the smooth muscles of the body causes a persistent and dangerous erection of the penis, which can be urgent medical care (priapism is much more complicated, so use the explanation as a metaphor).

If we are talking about "living spasm", there is an analogy with " muscle spasm"(And partly priapism), but I have to say that we believe that there is a spasm of the ciliary muscle, since we do not see it directly. Probably (and take this proposal as speculation, since I cannot give you a link right now), the reasons for this are not the muscle spasm itself, but the state of the ozone fibers that cannot return to their baseline state. I like the iron bar example - if you cut it quickly and many times, at some point it can be “loosened” and also broken (and it probably does with zones as well). It is likely (I say “possibly” to emphasize a point we don’t know exactly about) that “placement spasm” is partially mistaken, and future investigations will find out.

You may recognize some interesting Facts from the definition of pseudoexfoliation syndrome, but I am not explaining it here because it is not directly related to the question. From the wiki "is known to cause weakening of structures within the eye that help hold the lens of the eye in place, called the lens areas."

Another analogy for the continuation of the "spasm" is the situation when you need to care for something heavy at a long distance without releasing the grip - finally, you can get not only spasmodic contraction, but also severe ischemic injury to the fingers.

Considering your case, you should be aware of pathological (degenerative) myopia, where the eye expands backwards, and therefore the focus is in front of the retina, which must be corrected by minus lenses. It is well known that nearsighted eyes have a longer axial length than normal eyes. This is probably your business.

So, as you can see, the answer to your question is not a clear cut, but a guess. The ciliary muscle may relax, but the problem is probably more complex than the ciliary muscle problem.

PS The image you have restored is a little inconsistent with one and not accurate. This one is classic and gives a better understanding of anatomy -

Seeing off as ciliary muscle (FAT / shortened muscle) can cause loose eyes Lense ligaments (near vision) is what you need to grasp.

This Video Best Shows WHY and HOW does the contracting (FAT) muscle do it: " accomodation » https://www.youtube.com/watch?v\u003dp_xLO7yxgOk

When the ciliary muscle contract (close vision) the ligaments holding the lens of the eye in position become Loose.

When the muscles RELAXES (distant vision) the ligaments become TAUT.

thanks for accepting this old question - Welcome to BiologySE! We always appreciate some links / links to let other users know more about your answer - and that definitely strengthens the answer. - Vance l albaugh May 29. 16 2016-05-29 22:18:49

I am not an eye doctor, but I exercise. I would like to say something about your metaphor or comparison of the ciliary muscle with the muscles of the body.

Let's take a look at the workout. In a workout, you tense your muscles and then relax your muscles until you run out of muscles. The other part of the exercise is stretching. If you don't stretch, you will lose your full range of motion. For example, if I did my first bicep curl and I slept that night with my arm raised, it would be a painful effort to straighten it the next day. If I do not stretch it, my arm will remain in this position with limited movement. The muscle is relaxed, but the range has changed. Another example would be when I was a teenager, I did karate and could do splits. I am currently unable to do splits, no matter how relaxed my muscles are.

Looking at a computer all day is not comparable to a muscle, because you don't contract and relax again. You just agreed.

Now let's look at the muscles of the body in a more relevant metaphor - Tension. Stress is an involuntary reaction. Because you keep the muscle in a squeeze for so long, she tends to want to stay connected without you trying. Many people hold tight to their neck and shoulders, and no matter how painful they are, they cannot voluntarily relax.

Muscles have a mind of their own (muscle memory). Assuming you have complete control over them is wishful thinking. My guess is that the ciliary muscle is no different.

There are a few more things to consider in order to better understand physiology.

The ciliary muscles are not skeletal muscles (voluntary muscles that you can control), but smooth muscles (involuntary muscles, which are under the control of the autonomic nervous system, which is independently regulated by parts of the brain not under conscious control). This has several profound implications.

Smooth muscles are not hypertrophic - they grow and become thick like skeletal muscles - they are more or less permanent, and their growth / strengthening is more hormone-related than regular contraction / relaxation exercises

Smooth muscles are supplied autonomously nervous system. Parasympathetic system is the main source of food. Recently, evidence has been found for sympathetic innervation of the ciliary muscles.

Typically, there is a balance between sympathetic and parasympathetic, the balance of which is driven by the need of the brain. Imbalance in these systems can cause placement problems

This point is an assumption based on proven biological laws: The stress-stress law: This means that if biological systems grow under constant stress,

Gradual traction on living tissue creates tension that can stimulate and support the regeneration and growth of certain tissues. Slow, sustained tension of the tissue causes them to be metabolically activated, which leads to an increase in their proliferative and biosynthetic functions. These processes depend on two main factors:

the quantity and quality of tissue blood supply are mechanically emphasized and

The stimulating effect of tensile forces acting along the lines of muscle contraction, since the collagen fibers are usually aligned parallel to the tensile stress vector.

The ciliary (ciliary) muscle is a paired organ of the eyeball, which is involved in the process of accommodation.

Structure

Muscle consists of different types of fibers (meridional, radial, circular), which, in turn, perform different functions.

Meridian

The part that attaches to the limbus is adjacent to the sclera and partially extends into the trabecular meshwork. This part is also called the Brücke muscle. In a tense state, it moves forward and participates in the processes of focusing and disaccomodation (vision into the distance). This function helps to preserve the ability to project light onto the retina during sudden head movements. The contraction of the meridional fibers also promotes the circulation of the intraocular fluid, reminiscent of the eyebrows.ru, through the Schlemm canal.

Radial

Location - from scleral spur to ciliary processes. Also called Ivanov's muscle. Like meridional ones, it participates in disaccomodation.

Circular

Or Muller's muscles, located radially in the area of \u200b\u200bthe inner part of the ciliary muscle. In tension, the inner space narrows and the tension of the zinc ligament is weakened. The result of the contraction is the acquisition of a spherical lens. This change in focus is more favorable for near vision.

Gradually with age, the process of accommodation is weakened due to the loss of elasticity of the lens. Muscular activity does not lose its ability even in old age.

The blood supply to the ciliary muscle is carried out through three arteries, obaglaza.ru claims. The outflow of blood occurs through the anterior ciliary veins.

Diseases

With intense exertion (reading in transport, prolonged stay in front of a computer monitor) and overvoltage, a convulsive contraction develops. In this case, a spasm of accommodation occurs (false myopia). When such a process is delayed, it leads to true myopia.

With some injuries to the eyeball, the ciliary muscle can also be damaged. This can provoke absolute paralysis of accommodation (loss of the ability to see clearly at near).

Disease prevention

With prolonged exertion, in order to prevent disruption of the ciliary muscle, the site recommends the following:

do strengthening exercises for the eyes and cervical spine;
take breaks of 10 to 15 minutes every hour;
to refuse from bad habits;
take vitamins for the eyes.

This great idea will help you maintain your vision. We promise that you will feel the effect immediately !!!

Causes of visual impairment

There are 2 theories why a person's vision deteriorates. In my opinion and in my experience, they both take place.

Lens of the eye and ciliary muscles

First, let's take a look at why vision deteriorates:

Nearsightedness - corrected with a biconcave (reducing) lens.

Hyperopia - corrected with magnifying lenses

Briefly about the reasons: loss of elasticity of the lens, spasm or "insufficiency" of the ciliary muscle - the muscle that changes the curvature of the lens.

Supportive muscles of the eye: lateral, medial and others

The photo shows the right eye

We will not describe in detail how and which eye muscles work - this can be easily understood by looking at the picture. I want to say only one thing: due to the uneven load on the muscles, some of them spasm, and either change the shape of the eyeball (and then even with normal operation of the lens and ciliary muscles, the same picture is obtained as in the images above), or they simply “lead the eye to the side "- when you look at the monitor screen, both eyes look at one closely located point, and therefore only that muscle (medial) works, which turns / bevels the eye, so to speak, closer to the bridge of the nose. When you look into the distance, both eyes look straight ahead. So when you try to look into the distance after a long work at the computer, then my eyes cannot look exactly right because of the spasm of the medial muscle.

The method itself

A plate with pairs of balls, each ball has a number written on it.

How to use

Download and print for sight. There are 3 files in the archive. One table is immediately ready for printing (table_done.doc), in another (table.doc) - a macro, changing the parameters of which you can change appearance tables for specific needs (hereinafter - more in detail) and the third (table_done.pdf) - pdf (very convenient to use on a tablet). Print it out and hang it on the wall at eye level. Stand about 30 cm away from it and try to combine pairs of balls into one ball. In other words, each eye must be looking at a separate ball. The principle is the same as in these pictures.
As soon as you manage to combine the top pair into one ball - go down below. So try to get down as low as possible. With each new step down, you relax the muscles of the lens, making the image blurred like a "Gaussian" (to achieve this effect, look as if through a leaf into the distance), but not disconnected.

Thus, go up and down several times. Recently I have been using this plate on my tablet - very convenient and always at hand. The only thing - I turn down the screen brightness to a minimum.

Some clarifications and notes

There is a well-known exercise of changing the focus of vision, when you look at a point on a window and then look at a point somewhere in the distance. Here is the principle, BUT! If you lower yourself onto the lowest pair of balls, your eyes will literally spread apart, relaxing the medial and training the lateral muscle. In addition, due to the same force-relaxation, the ciliary muscle of the lens also reflexively relaxes.

About the macro and its parameters. I assumed that if with each new step the balls would increase or decrease, then this would be more effective for myopic or farsighted people, but it was not possible to test my hypothesis - there are no people who want to exercise regularly. Try it! It may be possible to correct the impaired vision. It will definitely not be worse (checked for 3 years on myself - I never wore glasses, my eyesight is excellent, I sit at the computer for days on end)

And finally, an additional quick blinking within a minute will also be useful, and circular motion eyes. All!

Due to the fact that it turns out there is still a "cross-look". The picture clearly illustrates. In order to understand how you look, you need to combine any pair of balls into one and close your left eye. If you are looking at the right ball with your right, then you are doing everything right, if you are looking at the left, then your "technique" is wrong! The right eye should be looking at the right ball, the left to the left

People with congenital myopia are better off not being zealous. Try, but don't overexert yourself. Congenital myopia or farsightedness is either a curved shape of the eyeball initially, or something with a lens (shape, elasticity). If congenital poor eyesight worsened over the years, it could be partly due to muscle spasm, then this technique may help somewhat.

The ciliary muscle is a pair of ocular muscles located inside the eyeball and providing accommodation.

The ciliary muscle consists of several types of smooth muscle fibers:

1. The meridional fibers that form the Brücke muscle adjacent to the sclera. It attaches to the inside of the limbus and is partly woven into the trabecular meshwork. When these fibers contract, the ciliary muscle moves forward. The Brücke muscle takes part in focusing on objects that are located at a distance, as well as in the process of disaccomodation. Due to this process, it becomes possible to project rays on the retina when turning the head, driving and other rapid movements in space. Also, with the contraction of muscle fibers, the rate of exchange of aqueous humor through the Schlemm canal changes.
2. Radial fibers are called Ivanov's muscles. It branches off from the scleral spur and follows towards the ciliary processes. Due to this, it provides a deaccommodation process.
3. Fibers located circularly are called Mueller's muscles. It is located on the inside of the ciliary muscle. When the fibers contract, the inner space narrows. In this regard, the tension of the zinn ligament is weakened, as a result of which the lens acquires a more spherical shape. Such a transformation of the lens leads to a change in optical power, that is, the focus is shifted to closer objects. With age, changes occur that lead to a weakening of accommodation. However, this is due to a violation of the elasticity of the lens, and not to the functional ability of the muscle.

The ciliary muscle is supplied with blood by four arteries that branch off from an artery in the eye. Venous outflow is carried out through the ciliary veins, which are located in front.

With prolonged load on the muscle (reading, computer), it begins to contract convulsively, which leads to a spasm of accommodation. This spasm is accompanied by false myopia and other visual impairments. With a prolonged course, the spasm of accommodation can develop into true myopia. For the prevention of such a condition, it is necessary to perform special gymnastics, which helps to train the muscle, and also prescribe magnetotherapy, electrophoresis. In some cases, traumatic damage to the ciliary muscle occurs, which leads to absolute paralysis of accommodation. You can get qualified advice on this matter in our