The muscular layer of the wall of the heart. The structure of the walls of the heart

The date: 04.03.2020

The automatism of the heart is its ability to rhythmically contract without any visible irritation under the influence of impulses that arise in the organ itself.

Automation of the heart, the nature of the rhythmic excitation of the heart, the structure and functions of the conduction system. Automatic Gradient. Disturbances in the rhythm of the heart (blockade, extrasystole).

The wall of the heart consists of three layers: the outer one - the epicardium, the middle one - the myocardium and the inner one - the endocardium.

Name the branches of the aortic arch

1.shoulder head trunk

2.left common carotid artery

3. left subclavian artery

List the branches of a. mesenterica superior and name the areas of their branching.

superior mesenteric artery, a. mesenterica superior, departs from the abdominal part of the aorta behind the body of the pancreas at the level of the XII thoracic - I lumbar vertebra. This artery gives off the following branches:

1) lower pancreat and duodenal arteries, aa. pancreaticoduodenales inferiores, arise from the superior mesenteric artery

2) jejunal arteries, aa. jejunales, and ileo-intestinal arteries, aa. iledles, depart from the left semicircle of the superior mesenteric artery.

3) ileocolic-intestinal artery, a. ileocolica, gives back anterior and posterior cecum arteries, aa. caecdles anterior et posterior, as well as artery of the appendix, a. appendicularis, and colonic branch, g. colicus, to the ascending colon;

4) right colic artery, a. colica dextra, starts a little higher than the previous one.

5) middle colic artery, a. colica media, departs from the superior mesenteric artery.

Name the branches of the popliteal artery.

Branches of the popliteal artery:

1. Lateral superior genicular artery, a. genus superior lateralis, blood supply to the broad and biceps muscles of the thigh and is involved in the formation of the knee articular network that feeds the knee joint.

2. Medial superior genicular artery, a. genus superior medialis, blood supply to the vastus medialis muscle of the thigh.

3. Middle knee artery, a. media genus, blood supply to the cruciate ligaments and menisci isinovial folds of the capsule.

4. Lateral inferior genicular artery, a. genus inferior lateralis, blood supply to the lateral head of the gastrocnemius muscle and the plantar muscle.

5. Medial inferior genicular artery, a. genus inferior medialis, blood supply to the medial head of the gastrocnemius muscle and is also involved in the formation knee articular network, rete articulare genus.

Ticket 3

1. What separates the right atrioventricular valve? indicate its folds

The right atrioventricular orifice is closed by the right atrioventricular valve.

It consists of 3 wings:

1.front flap

2.back

3.cloisonné

2. Name the branches of a.femoralis and the areas where they go

femoral artery,a. femoralis, is a continuation of the outer iliac artery. Branches from the femoral artery:

1. Superficial epigastric artery,a. epigastric superficialis, blood supply to the lower part of the aponeurosis of the external oblique muscle of the abdomen, subcutaneous tissue and skin.

2. Superficial artery, envelope of the ilium,a. circumflexa iliaca superjicialis, goes in a lateral direction parallel inguinal ligament to the superior anterior iliac spine, branches in the adjacent muscles and skin.

3. External pudendal arteries,aa. pudendae externa, exit through the subcutaneous fissure (hiatus saphenus) under the skin of the thigh and go to the scrotum - anterior scrotal branches, rr. scrotdles anteriors, in men or to the labia majora anterior labial branches, rr. labidles anteriores, among women.

4. Deep artery hips, a. profunda femoris, supplies blood to the thigh. The medial and lateral arteries depart from the deep artery of the thigh.

1) Medial circumflex artery femur, a. circumflexa femoris medialis, gives back ascending and deep branches, rr. ascendens et profundus, to iliopsoas, pectineus, obturator externus, piriformis and quadratus femoris muscles. The medial circumflex artery of the femur sends acetabular branch, g. acetabuldris, to hip joint.

2) Lateral circumflex artery of the femur, a. circumflexa femoris latertis, his ascending branch, r. ascendens, blood supply to the gluteus maximus muscle and tensor fascia lata. Descending and transverse branches, rr. descendens and transversus, blood supply to the muscles of the thigh (tailor and quadriceps).

3) Perforating arteries, aa. perfordntes(first, second and third), supply blood to the biceps, semitendinosus and semimembranosus muscles.

3.List the branches of a.mesenterica inferior and name their branching areas.

inferior mesenteric artery,a. mesenterica inferior, starts from the left semicircle of the abdominal part of the aorta at the level of the III lumbar vertebra, gives a number of branches to the sigmoid, descending colon and the left part of the transverse colon. A number of branches depart from the inferior mesenteric artery:

1) left colic artery, a. colica sinistra, Feeds the descending colon and the left section of the transverse colon.

2) sigmoid arteries, aa. sigmoideae, heading towards sigmoid colon;

3) superior rectal artery, a. rectalis superior, blood supply to the upper and middle sections of the rectum.

4. Name the branches of a thoracica interna

internal thoracic artery,a. thoracica interna, departs from the lower semicircle of the subclavian artery, splits into two terminal branches - the muscular-diaphragmatic and superior epigastric arteries. A number of branches depart from the internal mammary artery: 1) mediastinal branches, rr. mediastindles; 2) thymic branches, rr. thymici; 3) bronchial and tracheal branches, rr. bronchiales and tracheales; 4) pericardial diaphragmatic artery, a.pericardiacophrenica; 5) sternal branches, rr. sternales; 6) perforating branches, rr. perfordntes; 7) anterior intercostal branches, rr. intercosldles anteriores; 8) musculophrenic artery, a. muscutophrenica; 9) superior epigastric artery, a. epigdstrica superior.

5. Projection of the heart valves on the anterior chest wall.

The projection of the mitral valve is on the left above the sternum in the area of attachment of the 3rd rib, the tricuspid valve is on the sternum, in the middle of the distance between the place of attachment to the sternum of the cartilage of the 3rd rib on the left and the cartilage of the 5th rib on the right. The valve of the pulmonary trunk is projected in the II intercostal space to the left of the sternum, the aortic valve - in the middle of the sternum at the level of the third costal cartilage. The perception of sounds arising in the heart depends on the proximity of the projections of the valves, where sound vibrations are manifested, on the conduction of these vibrations along the blood flow, adherence to chest of the part of the heart in which these vibrations are formed. This allows you to find certain areas on the chest, where the sound phenomena associated with the activity of each valve are better heard.

It is he who protects our motor from injuries, penetration of infections, carefully fixes the heart in a certain position in the chest cavity, preventing its displacement. Let's talk in more detail about the structure and functions of the outer layer or pericardium.

1 Heart layers

The heart has 3 layers or shells. The middle layer is the muscular, or myocardium, (in Latin, the prefix myo- means "muscle"), the thickest and most dense. The middle layer provides contractile work, this layer is a true hard worker, the basis of our “motor”, it represents the main part of the organ. The myocardium is represented by a striated cardiac tissue endowed with special functions peculiar only to it: the ability to spontaneously excite and transmit an impulse to other cardiac departments through the conduction system.

Another important difference between the myocardium and the muscles of the skeleton is that its cells are not multicellular, but have one nucleus and represent a network. The myocardium of the upper and lower cardiac cavities is separated by horizontal and vertical partitions of the fibrous structure, these partitions provide the possibility of separate contraction of the atria and ventricles. The muscular layer of the heart is the basis of the organ. Muscle fibers are organized into bundles; in the upper chambers of the heart, a two-layer structure is distinguished: bundles of the outer layer and the inner one.

Muscular layer of the heart

A distinctive feature of the ventricular myocardium is that in addition to the muscle bundles of the surface layer and internal bundles, there is also a middle layer - separate bundles for each ventricle of the annular structure. The inner shell of the heart or endocardium (in Latin, the prefix endo- means “inner”) is thin, one cell epithelial layer thick. It lines the inner surface of the heart, all its chambers from the inside, and the heart valves consist of a double layer of the endocardium.

In structure, the inner shell of the heart is very similar to the inner layer blood vessels, blood collides with this layer as it passes through the chambers. It is important that this layer is smooth to avoid thrombosis, which can form when blood cells are destroyed by impact on the heart walls. This does not occur in a healthy organ, since the endocardium has a perfectly smooth surface. The outer surface of the heart is the pericardium. This layer is represented by the outer sheet of the fibrous structure and the inner - serous. Between the sheets of the surface layer there is a cavity - pericardial, with a small amount of fluid.

2 We delve into the outer layer

The structure of the wall of the heart

So, the pericardium is not at all a single outer layer of the heart, but a layer consisting of several plates: fibrous and serous. Fibrous pericardium is dense, external. It performs to a greater extent a protective function and the function of a certain fixation of the organ in the chest cavity. And the inner, serous layer fits snugly directly to the myocardium, this inner layer is called the epicardium. Imagine a bag with a double bottom? This is what the outer and inner pericardial sheets look like.

The gap between them is the pericardial cavity, normally it contains from 2 to 35 milliliters of serous fluid. The liquid is needed for softer friction of the layers against each other. The epicardium densely covers the outer layer of the myocardium, as well as the initial sections largest vessels heart, its other name is the visceral pericardium (in Latin viscera - organs, viscera), i.e. this is the layer directly lining the heart. And already the parietal pericardium is the outermost layer of all the membranes of the heart.

The following sections or walls are distinguished in the superficial pericardial layer, their name depends directly on the organs and areas to which the shell is attached. Walls of the pericardium:

Anterior wall of the pericardium. Attached to the chest wall
diaphragmatic wall. This shell wall is directly fused with the diaphragm.
Lateral or pleural. Allocate on the sides of the mediastinum, adjacent to the pulmonary pleura.
back. Borders on the esophagus, descending aorta.

The anatomical structure of this shell of the heart is not easy, because in addition to the walls, there are also sinuses in the pericardium. These are such physiological cavities, we will not delve into their structure. It is enough to know that between the sternum and the diaphragm there is one of these pericardial sinuses - the anteroinferior one. It is her, in pathological conditions, that is pierced or punctured by health workers. This diagnostic manipulation is high-tech and complex, carried out by specially trained personnel, often under ultrasound control.

3 Why does the heart need a bag?

Pericardium and its structure

Our main "motor" of the body requires extremely careful attitude and care. Probably, for this purpose, nature dressed the heart in a bag - the pericardium. First of all, it performs the function of protection, carefully wrapping the heart in its shells. Also, the pericardial bag fixes, fixes our “motor” in the mediastinum, preventing displacement during movements. This is possible due to the strong fixation of the surface of the heart with the help of ligaments to the diaphragm, sternum, vertebrae.

The role of the pericardium as a barrier to cardiac tissues from various infections should be noted. The pericardium "fences off" our "motor" from other organs of the chest, clearly determining the position of the heart and helping the heart chambers to fill with blood better. At the same time, the superficial layer prevents excessive expansion of the organ due to sudden overloads. Prevention of overdistension of the chambers is another important role of the outer wall of the heart.

4 When the pericardium "sick"

Pericarditis - inflammation of the pericardial sac

Inflammation of the outer lining of the heart is called pericarditis. The causes of the inflammatory process can be infectious agents: viruses, bacteria, fungi. Also, this pathology can be provoked by a chest injury, directly by cardiac pathology, for example, an acute heart attack. Also, exacerbation of systemic diseases such as SLE, rheumatoid arthritis, can serve as the beginning in a chain of inflammatory phenomena of the superficial cardiac layer.

Not infrequently, pericarditis accompanies tumor processes in the mediastinum. Depending on how much fluid is released into the pericardial cavity during inflammation, dry and effusion forms of the disease are isolated. Often these forms in this order replace each other with the course and progression of the disease. Dry cough, pain in the chest, especially with a deep breath, a change in body position, during coughing are characteristic of the dry form of the disease.

The effusion form is characterized by a slight decrease in the severity of pain, and at the same time, retrosternal heaviness, shortness of breath, and progressive weakness appear. With a pronounced effusion into the pericardial cavity, the heart is as if squeezed into a vise, the normal ability to contract is lost. Shortness of breath haunts the patient even at rest, active movements become completely impossible. The risk of cardiac tamponade increases, which is fatal.

5 Heart injection or pericardial puncture

This manipulation can be carried out both for diagnostic purposes and for therapeutic purposes. The doctor performs a puncture with a threat of tamponade, with significant effusion, when it is necessary to pump out fluid from the heart sac, thereby providing the organ with the opportunity to contract. For diagnostic purposes, a puncture is performed to clarify the etiology or cause of inflammation. This manipulation is very complicated and requires a highly qualified doctor, since during its implementation there is a risk of damage to the heart.

Aortic aneurysm of the heart - what is it?

What is cardiac bradycardia

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The structure of the wall of the heart.

Internal structure of the heart.

The human heart has 4 chambers (cavities): two atria and two ventricles (right and left). One chamber is separated from the other by partitions.

transverse baffle divides the heart into atria and ventricles.

longitudinal partition, in which two parts are distinguished: interatrial and interventricular, divides the heart into two halves that do not communicate with each other - right and left.

In the right half is the right atrium and right ventricle and venous blood flows

In the left half is the left atrium and left ventricle and arterial blood flows.

There is an oval fossa on the interatrial septum of the right atrium.

The following vessels enter the atrium:

1. superior and inferior vena cava

2. the smallest veins of the heart

3. opening of the coronary sinus

On the lower wall of this atrium is the right atrioventricular opening, in which there is a tricuspid valve that prevents the reverse flow of blood from the ventricle to the atrium.

The right ventricle is separated from the left ventricular septum.

The right ventricle is divided into two sections:

1) front, in which there is an arterial cone passing into the pulmonary trunk.

2) rear(actual cavity), it has fleshy trabeculae, passing into the papillary muscles, tendon chords (filaments) depart from them, heading to the cusps of the right atrioventricular valve.

4 pulmonary veins flow into it, through which arterial blood enters. On the lower wall of this atrium there is a left atrioventricular opening, in which the bicuspid valve (mitral) is located.

The left ventricle has two sections:

1) anterior section from which the aortic cone originates.

2) back department(actually the cavity), it has fleshy trabeculae, passing into the papillary muscles, tendon chords (threads) depart from them, heading to the cusps of the left atrioventricular valve.

There are two types of valves:

1. Leaf valves - there are two and three leaf valves.

Butterfly valve located in the left atrioventricular orifice.

Tricuspid valve located in the right atrioventricular orifice.

The structure of these valves is as follows: the valve leaflet is connected by means of chords to the papillary muscles. Contracting, the muscles pull the chords, the valves open. When the muscles relax, the valves close. These valves prevent back flow of blood from the ventricles to the atria.

2. The semilunar valves are located together with the exit of the aorta and the pulmonary trunk. They block the flow of blood from the arteries to the ventricles.

The valves consist of three semi-lunar flaps - a pocket, in the center of which there is a thickening - nodules. They provide a complete seal when the semilunar valves are closed.

The wall of the heart consists of three layers: the inner one - the endocardium, the middle, thickest one - the myocardium and the outer one - the epicardium.

1. The endocardium lines all the cavities of the heart from the inside, covers the papillary muscles with their tendon chords (threads), forms the atrioventricular valves, the valves of the aorta, the pulmonary trunk, as well as the valves of the inferior vena cava and coronary sinus.

Consists of connective tissue with elastic fibers and smooth muscle cells, as well as endothelium.

2. Myocardium (muscle layer) is the contractile apparatus of the heart. The myocardium is made up of cardiac muscle tissue.

The atrial muscles are completely separated from the ventricular muscles by fibrous rings located around the atrioventricular openings. Fibrous rings, together with other accumulations of fibrous tissue, make up a kind of skeleton of the heart, which serves as a support for the muscles and valvular apparatus.

The muscular layer of the atria consists of two layers: superficial and deep. It is thinner than the muscular membrane of the ventricles, consisting of three layers: inner, middle and outer. In this case, the muscle fibers of the atria do not pass into the muscle fibers of the ventricles; the atria and ventricles contract at the same time.

3. The epicardium is the outer shell of the heart, covering its muscle and tightly fused with it. At the base of the heart, the epicardium wraps up and passes into the pericardium.

The pericardium is a pericardial sac that insulates the heart from surrounding organs and prevents overstretching.

The pericardium consists of an inner visceral plate (epicardium) and an outer parietal (parietal) plate.

Between the two plates of the pericardium - parietal and epicardial there is a slit-like space - the pericardial cavity, which contains a small amount (up to 50 ml) of serous fluid, which reduces friction during heart contractions.

The structure of the walls of the heart

endocardium - thin inner layer;
myocardium - thick muscle layer;
epicardium - a thin outer layer, which is the visceral sheet of the pericardium - the serous membrane of the heart (heart sac).

The middle layer of the heart wall is made up of

Answers and explanations

The walls of the heart are made up of three layers:

endocardium - thin inner layer; myocardium - thick muscle layer; epicardium - a thin outer layer, which is the visceral sheet of the pericardium - the serous membrane of the heart (heart sac).

The endocardium lines the cavity of the heart from the inside, exactly repeating its complex relief. The endocardium is formed by a single layer of flat polygonal endotheliocytes located on a thin basement membrane.

The myocardium is formed by cardiac striated muscle tissue and consists of cardiac myocytes interconnected by a large number of bridges, with the help of which they are connected into muscle complexes that form a narrow-loop network. Such a muscular network provides rhythmic contraction of the atria and ventricles. At the atria, the thickness of the myocardium is the smallest; in the left ventricle - the greatest.

The atrial myocardium is separated by fibrous rings from the ventricular myocardium. The synchrony of myocardial contractions is provided by the conduction system of the heart, which is the same for the atria and ventricles. In the atria, the myocardium consists of two layers: superficial (common to both atria), and deep (separate). In the superficial layer, the muscle bundles are located transversely, in the deep layer - longitudinally.

The myocardium of the ventricles consists of three different layers: outer, middle and inner. In the outer layer, the muscle bundles are oriented obliquely, starting from the fibrous rings, continuing down to the apex of the heart, where they form a heart curl. The inner layer of the myocardium consists of longitudinally arranged muscle bundles. Due to this layer, papillary muscles and trabeculae are formed. The outer and inner layers are common to both ventricles. The middle layer is formed by circular muscle bundles, separate for each ventricle.

The epicardium is built according to the type of serous membranes and consists of a thin plate of connective tissue covered with mesothelium. The epicardium covers the heart, the initial sections of the ascending aorta and pulmonary trunk, the final sections of the caval and pulmonary veins.

133. Layers of the wall of the heart, their functions.

The heart, cor (Greek cardia), is a hollow organ, the walls of which consist of three layers - inner, middle, outer.

Inner shell, endocardium, endocardium is represented by a layer of endotheliocytes. The endocardium covers all the structures inside the chambers of the heart. Its derivatives are all the valves and dampers in the heart. This sheath provides laminar blood flow.

Middle shell, myocardium, myocardium is formed by striated muscle cells (cardiomyocytes). Provides contraction of the atria and ventricles.

outer shell, epicardium, epicardium is represented by a serous membrane, which is the visceral sheet of the pericardium. The shell provides free displacement of the heart during its contraction.

134. The degree of expression of the muscle layer in the chambers of the heart.

The muscle layer has a different thickness in the chambers of the heart, which depends on the work performed by them. Maximum thickness this layer - in the left ventricle, tk. it ensures the movement of blood through the systemic circulation, overcoming the enormous forces of friction. In second place is the thickness of the myocardium in the wall of the right ventricle, which provides blood flow through the pulmonary circulation. And, finally, this layer is least expressed in the walls of the atria, which ensure the movement of blood from them into the ventricles.

135. Features of the structure of the myocardium of the ventricles and atria.

In the atria, the myocardium consists of two layers: superficial- common to both ventricles and deep- separate for each of them.

In the ventricles, the myocardium consists of three layers: external (surface), middle and internal (deep).

The outer and inner layers are common to both ventricles, while the middle layer is separate for each ventricle. The muscle fibers of the atria and ventricles are isolated from each other.

Derivatives of the deep layer of the ventricular myocardium are papillary muscles and fleshy trabeculae.

Derivatives of the outer layer of the atrial myocardium are the pectinus muscles.

136. Large and small circles of blood circulation, their functions.

Systemic circulation provides blood flow in the following direction: from the left ventricle → to the aorta → to the organ arteries → to the MCR of organs → to the organ veins → to the vena cava → to the right atrium.

Small circle of blood circulation provides blood flow in a different direction: from the right ventricle → into the pulmonary trunk → into the pulmonary arteries → into the ICR of the lung acini → into the pulmonary veins → into the left atrium.

Both circles of blood circulation are components of a single circle of blood circulation and perform two functions - transport and exchange. In the small circle, the metabolic function is mainly associated with the gas exchange of oxygen and carbon dioxide.

137. Heart valves, their functions.

The heart has four valves: two valvular and two semilunar.

Right atrioventricular (tricuspid) valve located between the right atrium and ventricle.

Left atrioventricular (mitral) valve located between the left atrium and ventricle.

Pulmonary valve, valva trunci pulmonalis is located within the base of the pulmonary trunk.

aortic valve, valva aortae is located within the base of the aorta.

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The structure of the wall of the heart

endocardium, average - myocardium, outdoor - epicardium

Endocardium -

Myocardium -

surface layer, outer longitudinal, average roundabout and interior

fibrous rings

conducting system sinoatrial

2) atrioventricular node

epicardium pericardium,

blood supply

The structure of the wall of the heart

Anatomical and physiological features of the cardiovascular system

The circulatory system consists of the heart - the central organ of blood circulation, the rhythmic contraction of which determines this movement, and blood vessels. The vessels through which blood from the heart enters the organs are called arteries, and the vessels that bring blood to the heart are called veins (Fig. 3).

The heart is a hollow muscular organ with a mass gr., cone-shaped. It is located in the chest cavity between the lungs, in the lower mediastinum.

In the chest cavity, the heart occupies an oblique position and faces its wide part - the base, up, back and right, and narrow - tip, forward, down and left; 2/3 it is located in the left half of the chest cavity.

Figure 3 - Heart; lengthwise cut.

1 - superior vena cava; 2 - right atrium; 3 - right atrioventricular valve; 4 - right ventricle; 5 - interventricular septum; 6 - left ventricle; 7 - papillary muscles; 8 - tendon chords; 9 - left atrioventricular valve; 10 - left atrium; 11 - pulmonary veins; 12 - aortic arch.

The boundaries of the heart are variable and depend on age, gender, human constitution and body position. The length of the heart in adults is 8.7-14.0 cm, the largest transverse size of the heart is 5-8 cm, anteroposterior - 6-8 cm on the surface of the heart are noticeable interventricular sulci: anterior and posterior, covering the heart in front and behind, and transverse coronal sulcus, arranged in a ring. Along these furrows are the own arteries and veins of the heart. These grooves correspond to partitions dividing the heart into 4 sections: longitudinal intercostal and interventricular septa divide the organ into two isolated halves - right and left heart; a transverse partition divides each of these halves into an upper chamber - atrium and bottom- ventricle.

The atria take blood from the veins and push it into the ventricles, the ventricles eject the blood into the arteries; right - through the aorta, from which numerous arteries depart to the organs and walls of the body. Each atrium communicates with the corresponding ventricle and atrioventricular arteries. The right side of the heart contains venous blood, while the left side contains arterial blood.

Right atrium - is a cavity with a volume of ml., resembles a cube in shape, is located at the base of the heart on the right and behind the aorta and pulmonary trunk. It serves as the confluence of the hollow veins and the veins of the heart itself. Its upper part is atrial appendage.

In the wall of the ear, the heart muscle forms muscular protrusions, located approximately in parallel, which are called comb muscles. In the area of confluence of the inferior vena cava there is a small valve, which is its damper. On the inner wall of the right atrium there is oval fossa(in the fetus, this is an opening through which blood passes from the right atrium into the left atrium, since the fetus does not have a small circle of blood circulation). Below and behind the edge of the oval fossa is the confluence coronary sinus, which collects most of the blood from the wall of the heart itself. The sinus opening is closed by the coronary sinus valve. The passage between the right atrium and the right ventricle is called the right atrioventricular orifice. During systole, the right ventricle closes. right atrioventricular(tricuspid) valve that separates the cavity of the right ventricle from the right atrium and does not allow blood to flow back into the right atrium. During ventricular diastole, the valve opens towards the ventricle.

Right ventricle it is separated from the left ventricle by the interventricular septum, most of which is muscular, and the smaller one, located in the very upper section, closer to the atria, - membranous. Above in the wall of the stomach two holes: behind - the right atrioventricular, and in front - the opening of the pulmonary trunk. The elongated funnel-shaped portion of the ventricle in this place is called arterial cone. Directly above the opening of the pulmonary trunk, consisting of anterior, left and right semilunar dampers, located in a circle, with a convex surface into the cavity of the right ventricle, and a concave and free edge - into the lumen of the pulmonary trunk. On the free edge, each of the flaps has a thickening - a knot, which contributes to a more dense closing of the semilunar flaps when they are closed. When the muscles of the ventricle contract, the semilunar valves are pressed against the wall of the pulmonary trunk by blood flow and do not prevent the passage of blood from the ventricle; during relaxation, when the pressure in the cavity of the ventricle decreases, the return flow of blood fills the pockets between the wall of the pulmonary trunk and each of the semilunar valves and closes (opens) the valves, their edges close and do not allow blood to pass to the heart.

The right atrioventricular orifice is closed by the right atrioventricular valve, having anterior, posterior and medial cusps. The latter fill the triangular tendon plates. On the inner surface of the right ventricle, fleshy trabeculae and cone-shaped nipple muscles, from which to the edges and surfaces of the valves go tendon chords. During atrial contraction, the valve leaflets are pressed by the blood flow against the walls of the ventricle and do not prevent its passage into the cavity of the latter. When the muscles of the ventricle contract, the free edges of the valves close and are held in this position by the tendon chords and contraction of the papillary muscles, preventing blood from flowing back into the atrium.

Left atrium limited from the right intercardiac septum; It has left ear. In the posterior section of the upper wall, 4 pulmonary veins open into it, devoid of valves, through which arterial blood flows from their lungs. Communicates with the left ventricle through the left atrioventricular orifice.

left ventricle in the anterior upper section aortic opening. At the exit of the aorta from the left ventricle aortic valve, consisting of right, left and rear semilunar flaps. The atrioventricular orifice contains the left atrioventricular valve- (bicuspid mitral). Consisting of front and rear wings of a triangular shape. On the inner surface of the left ventricle there are fleshy trabeculae and 2 papillary muscles, from which there are thick tendon chords that attach to the mitral valve leaflets.

The wall of the heart consists of three layers. The inner one is called endocardium, average - myocardium, outdoor - epicardium

Endocardium - lines all the cavities of the heart, tightly fused with the underlying muscle layer. From the side of the cavities of the heart, it is lined with endothelium. The endocardium forms the atrioventricular valves, as well as the valves of the aorta and pulmonary trunk.

Myocardium - is the thickest and functionally most powerful part of the heart wall. It is formed by cardiac striated muscle tissue and consists of cardiac myocytes (cardiomyocytes) interconnected by a large number of jumpers (intercalary discs), with the help of which they are connected into muscle complexes or fibers that form a narrow-loop network. It provides a complete rhythmic contraction of the atria and ventricles.

The muscle layer of the walls of the atria is thin due to a small load and consists of surface layer, common to both atria, and deep, separate for each of them. In the walls of the ventricles, it is the most significant in thickness; outer longitudinal, average roundabout and interior longitudinal layer. The outer fibers in the region of the apex of the heart pass into the inner longitudinal fibers, and between them are the circular muscle fibers of the middle layer. The muscular layer of the left ventricle is the thickest.

The muscle fibers of the atria and ventricles begin from the fibrous rings located around the right and left atrioventricular openings, which completely separate the atrial myocardium from the ventricular myocardium.

fibrous rings form a kind of skeleton of the heart, which also includes thin connective tissue rings around the openings of the aorta and pulmonary trunk and the right and left fibrous triangles adjacent to them.

The composition of the cardiac striated muscle tissue includes typical contractile muscle cells - cardiomyocytes and atypical cardiac myocytes, which form the so-called conducting system- consisting of nodes and bundles, providing automatism of heart contractions, as well as coordination contractile function atrial and ventricular myocardium. The centers of the conduction system of the heart are 2 nodes: 1) sinoatrial node (Kiss-Flex node), it is called the pacemaker of the heart. Located in the wall of the right atrium between the opening of the superior vena cava and the right ear and the giving branch to the atrial myocardium.

2) atrioventricular node(Ashoff-Tavara node) is located in the septum between the atrium and the ventricles. From this node departs atrioventricular bundle(bundle of His), which connects the atrial myocardium with the ventricular myocardium. In the interventricular septum, this bundle divides into right and left legs to the myocardium of the right and left ventricles. The heart receives innervation from the vagus and sympathetic nerves.

In recent years, in the myocardium of the right atrium, endocrine cardiomyocytes have been described that secrete a number of hormones (cardiopatrin, cardiodilatin), which regulate the blood supply to the heart muscle.

epicardium is part of the fibro-serous membrane pericardium, covering the heart. In the pericardium, 2 layers are distinguished: the fibrous pericardium, formed by dense fibrous connective tissue, and the serous pericardium, also consisting of fibrous tissue with elastic fibers. It adheres tightly to the myocardium. In the region of the furrows of the heart, in which its blood vessels pass, under the epicardium is often possible from the surrounding organs, and the serous fluid between its plates reduces friction during heart contractions.

blood supply of the heart occurs through the coronary arteries, which are branches (right and left) of the outgoing part of the aorta, extending from it at the level of its valves. The right branch goes not only to the right, but also backwards, descending along the posterior interventricular sulcus of the heart, the left branch goes to the left and anteriorly, along the anterior interventricular sulcus. Most of the veins of the heart are collected in the coronary sinus, which flows into the right atrium and is located in the coronary sulcus. In addition, individual small veins of the heart itself flow directly into the right atrium.

The pulmonary trunk at the place of its exit from the right ventricle is located in front of the aorta. Between the pulmonary artery and the lower surface of the aortic arches is the arterial ligament, which is an overgrown ductus arteriosus (botalla) functioning during the prenatal period of life.

It is he who protects our motor from injuries, penetration of infections, carefully fixes the heart in a certain position in the chest cavity, preventing its displacement. Let's talk in more detail about the structure and functions of the outer layer or pericardium.

1 Heart layers

Muscular layer of the heart

In structure, the inner shell of the heart is very similar to the inner layer of blood vessels, blood collides with this layer as it passes through the chambers. It is important that this layer is smooth to avoid thrombosis, which can form when blood cells are destroyed by impact on the heart walls. This does not occur in a healthy organ, since the endocardium has a perfectly smooth surface. The outer surface of the heart is the pericardium. This layer is represented by the outer sheet of the fibrous structure and the inner - serous. Between the sheets of the surface layer there is a cavity - pericardial, with a small amount of fluid.

2 We delve into the outer layer

The structure of the wall of the heart

The gap between them is the pericardial cavity, normally it contains from 2 to 35 milliliters of serous fluid. The liquid is needed for softer friction of the layers against each other. The epicardium tightly covers the outer layer of the myocardium, as well as the initial sections of the largest vessels of the heart, its other name is the visceral pericardium (in Latin viscera - organs, viscera), i.e. this is the layer directly lining the heart. And already the parietal pericardium is the outermost layer of all the membranes of the heart.

The following sections or walls are distinguished in the superficial pericardial layer, their name depends directly on the organs and areas to which the shell is attached. Walls of the pericardium:

Anterior wall of the pericardium. Attached to the chest wall
diaphragmatic wall. This shell wall is directly fused with the diaphragm.
Lateral or pleural. Allocate on the sides of the mediastinum, adjacent to the pulmonary pleura.
back. Borders on the esophagus, descending aorta.

3 Why does the heart need a bag?

Pericardium and its structure

4 When the pericardium "sick"

Pericarditis - inflammation of the pericardial sac

Inflammation of the outer lining of the heart is called pericarditis. The causes of the inflammatory process can be infectious agents: viruses, bacteria, fungi. Also, this pathology can be provoked by a chest injury, directly by cardiac pathology, for example, an acute heart attack. Also, the exacerbation of such systemic diseases as SLE, rheumatoid arthritis, can serve as the beginning in a chain of inflammatory phenomena of the superficial cardiac layer.

The effusion form is characterized by a slight decrease in the severity of pain, and at the same time, retrosternal heaviness, shortness of breath, and progressive weakness appear. With a pronounced effusion into the pericardial cavity, the heart is as if squeezed into a vise, the normal ability to contract is lost. Shortness of breath haunts the patient even at rest, active movements become completely impossible. The risk of cardiac tamponade increases, which is fatal.

5 Heart injection or pericardial puncture

Aortic aneurysm of the heart - what is it?

What is cardiac bradycardia

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Heart - how does it work?

Some facts about the work of the heart

How does this ideal engine work?

chambers of the heart

These parts of the heart are separated by partitions, between the chambers the blood circulates through the valvular apparatus.

The walls of the atria are quite thin - this is due to the fact that when the muscle tissue of the atria contracts, they have to overcome much less resistance than the ventricles.

The walls of the ventricles are many times thicker - this is due to the fact that it is thanks to the efforts of the muscle tissue of this part of the heart that the pressure in the pulmonary and systemic circulation reaches high values and provides a continuous flow of blood.

valve apparatus

2 atrioventricular valves ( as the name suggests, these valves separate the atria from the ventricles)
one pulmonary valve through which blood moves from the heart to circulatory system lung)
one aortic valve this valve separates the aortic cavity from the left ventricular cavity).

The valvular apparatus of the heart is not universal - valves have a different structure, size and purpose.

More about each of them:

Layers of the heart wall

1. The outer mucosal layer is the pericardium. This layer allows the heart to glide while working inside the heart sac. It is thanks to this layer that the heart does not disturb the surrounding organs with its movements.

Some information about the hydrodynamics of the heart

Phases of the contraction of the heart

How is the heart supplied with blood?

What controls the work of the heart?

Further, the excitation covers the muscular tissue of the ventricles - there is a synchronous contraction of the walls of the ventricles. The pressure inside the chambers builds up, causing the atrioventricular valves to close and simultaneously open the aortic and pulmonic valves. At the same time, the blood continues its unidirectional movement towards lung tissue and other organs.

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The structure of the walls of the heart

The walls of the heart are made up of three layers:

endocardium - thin inner layer;
myocardium - thick muscle layer;
epicardium - a thin outer layer, which is the visceral sheet of the pericardium - the serous membrane of the heart (heart sac).

The structure of the wall of the heart

The wall of the heart includes three shells: the inner one - the endocardium, the middle one - the myocardium and the outer one - the epicardium.

The structure of the wall of the heart

Endocardium, endocardium, a relatively thin shell that lines the chambers of the heart from the inside. As part of the endocardium, there are: endothelium, subendothelial layer, muscular-elastic and external connective tissue. The endothelium is represented by only one layer of flat cells. The endocardium without a sharp border passes to large cardiac vessels. The cusps of the cuspid valves and the cusps of the semilunar valves represent a duplication of the endocardium.

Myocardium, myocardium, is the most significant shell in thickness and the most important in function. The myocardium is a multitissue structure consisting of striated muscle tissue, loose and fibrous connective tissue, atypical cardiomyocytes, blood vessels, and nerve elements. The collection of contractile muscle cells makes up the heart muscle. The cardiac muscle has a special structure, occupying an intermediate position between striated and smooth muscles. The fibers of the heart muscle are capable of rapid contractions, are interconnected by jumpers, as a result of which a wide-loop network is formed, called syncytium. Muscle fibers are almost devoid of a sheath, their nuclei are in the middle. The contraction of the muscles of the heart is automatic. The muscles of the atria and ventricles are anatomically separate. They are connected only by a system of conductive fibers. The atrial myocardium has two layers: a superficial one, the fibers of which run transversely, covering both atria, and a deep separate one for each atrium. The latter consists of vertical bundles starting from the fibrous rings in the region of the atrioventricular openings and from circular bundles located at the mouths of the hollow and pulmonary veins.

The ventricular myocardium is much more complex than the atrial myocardium. There are three layers: outer (superficial), middle and inner (deep). The bundles of the surface layer, common to both ventricles, start from the fibrous rings, go obliquely - from top to bottom to the top of the heart. Here they turn back, go into the depths, forming in this place a curl of the heart, vortex cordis. Without interruption, they pass into the inner (deep) layer of the myocardium. This layer has a longitudinal direction, forms fleshy trabeculae and papillary muscles.

Between the superficial and deep layers lies the middle - circular layer. It is separate for each of the ventricles, and is better developed on the left. Its bundles also start from the fibrous rings and run almost horizontally. Between all muscle layers there are numerous connecting fibers.

In the wall of the heart, in addition to muscle fibers, there are connective tissue formations - this is the heart's own "soft skeleton". It plays the role of supporting structures from which muscle fibers begin and where the valves are fixed. The soft skeleton of the heart includes four fibrous rings, nnuli fibrosi, two fibrous triangles, trigonum fibrosum, and the membranous part of the interventricular septum, pars membranacea septum interventriculare.

Myocardial muscle tissue

Fibrous rings, annlus fibrosus dexter et sinister, surround the right and left atrioventricular openings. Provide support for tricuspid and bicuspid valves. The projection of these rings on the surface of the heart corresponds to the coronary sulcus. Similar fibrous rings are located in the circumference of the mouth of the aorta and the pulmonary trunk.

The right fibrous triangle is larger than the left one. It occupies a central position and actually connects the right and left fibrous rings and the connective tissue ring of the aorta. From below, the right fibrous triangle is connected to the membranous part of the interventricular septum. The left fibrous triangle is much smaller, it connects to the anulus fibrosus sinister.

The base of the ventricles, the atria are removed. Mitral valve lower left

Atypical cells of the conducting system, which form and conduct impulses, ensure the automaticity of the contraction of typical cardiomyocytes. They make up the conduction system of the heart.

Thus, in the composition of the muscular membrane of the heart, three functionally interconnected apparatuses can be distinguished:

1) Contractile, represented by typical cardiomyocytes;

2) Support formed by connective tissue structures around natural holes and penetrating into the myocardium and epicardium;

3) Conductive, consisting of atypical cardiomyocytes - cells of the conduction system.

Epicardium, epicardium, covers the heart from the outside; under it are the own vessels of the heart and fatty tissue. It is a serous membrane and consists of a thin plate of connective tissue covered with mesothelium. The epicardium is also called the visceral plate of the serous pericardium, lamina visceralis pericardii serosi.

The structure of the walls of the heart

Three layers are distinguished in the wall of the heart: a thin inner layer - the endocardium, a thick muscle layer - the myocardium and a thin outer layer - the epicardium, which is a visceral sheet of the serous membrane of the heart - the pericardium (pericardial sac).

Endocardium (endocardium) lines the cavity of the heart from the inside, repeating its complex relief, and covers the papillary muscles with their tendon chords. The atrioventricular valves, the aortic valve and the pulmonary valve, as well as the valves of the inferior vena cava and the coronary sinus, are formed by duplications of the endocardium, inside which connective tissue fibers are located.

The endocardium is formed by a single layer of flat polygonal endotheliocytes located on a thin basement membrane. The cytoplasm of endotheliocytes contains a large number of micropinocytic vesicles. Endotheliocytes are connected to each other by intercellular contacts, including nexuses. On the border with the myocardium there is a thin layer of loose fibrous connective tissue. The middle layer of the heart wall - myocardium (myocardium), is formed by cardiac striated muscle tissue and consists of cardiac myocytes (cardiomyocytes). Cardiomyocytes are interconnected by a large number of jumpers (intercalary discs), with the help of which they are connected into muscle complexes that form a narrow-loop network. This muscular network provides a complete rhythmic contraction of the atria and ventricles. The thickness of the myocardium is the smallest in the atria, and the largest - in the left ventricle.

atrial myocardium separated by fibrous rings from the myocardium of the ventricles. The synchrony of myocardial contractions is provided by the conduction system of the heart, which is the same for the atria and ventricles. In the atria, the myocardium consists of two layers: superficial, common to both atria, and deep, separate for each of them. In the superficial layer, the muscle bundles are located transversely, in the deep layer - longitudinally. Circular muscle bundles loop around the mouths of the veins that flow into the atria, like constrictors. Longitudinally lying muscle bundles originate from the fibrous rings and in the form of vertical strands protrude into the cavities of the auricles of the atria and form the pectinate muscles.

Myocardium of the ventricles consists of three different muscle layers: outer (superficial), middle and inner (deep). The outer layer is represented by obliquely oriented muscle bundles, which, starting from the fibrous rings, continue down to the top of the heart, where they form a heart curl (vortex cordis). Then they pass into the inner (deep) layer of the myocardium, the bundles of which are located longitudinally. Due to this layer, papillary muscles and fleshy trabeculae are formed. The outer and inner layers of the myocardium are common to both ventricles. The middle layer located between them, formed by circular (circular) muscle bundles, is separate for each ventricle. The interventricular septum is formed in its greater part (its muscular part) by the myocardium and the endocardium covering it. The basis of the upper section of this septum (its membranous part) is a plate of fibrous tissue.

The outer shell of the heart - the epicardium (epicardium), adjacent to the myocardium from the outside, is a visceral sheet of the serous pericardium. The epicardium is built according to the type of serous membranes and consists of a thin plate of connective tissue covered with mesothelium. The epicardium covers the heart, the initial sections of the ascending aorta and pulmonary trunk, the final sections of the caval and pulmonary veins. Through these vessels, the epicardium passes into the parietal plate of the serous pericardium.

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Portnov Alexey Alexandrovich

Education: Kyiv National Medical University. A.A. Bogomolets, specialty - "Medicine"

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The structure of the wall of the heart.

The steppe of the heart consists of three layers: the outer one - the epicardium, the middle one - the myocardium and the inner one - the endocardium. The outer shell of the heart. The epicardium, epicardium, is a smooth, thin and transparent shell. It is a visceral plate, lamina visceralis, pericardium, pericardium. The connective tissue base of the epicardium in various parts of the heart, especially in the sulci and in the apex, includes adipose tissue. With the help of connective tissue, the epicardium is fused with the myocardium most tightly in places of the least accumulation or absence of adipose tissue (see "Pericardium").

The muscular layer of the heart, or myocardium. The middle, muscular, shell of the heart, myocardium, or cardiac muscle, is a powerful and significant part of the wall of the heart in thickness. The myocardium reaches its greatest thickness in the region of the wall of the left ventricle (11-14 mm), twice the thickness of the wall of the right ventricle (4-6 mm). In the walls of the atria, the myocardium is much less developed and its thickness here is only 2–3 mm.

Between the muscular layer of the atria and the muscular layer of the ventricles lies dense fibrous tissue, due to which fibrous rings are formed, right and left, anuli fibrosi, dexter et sinister. On the side of the outer surface of the heart, their location corresponds to the coronary sulcus.

The right fibrous ring, anulus fibrosus dexter, which surrounds the right atrioventricular orifice, is oval in shape. The left fibrous ring, anulus fibrosus sinister, surrounds the left atrioventricular opening on the right, left and behind and is horseshoe-shaped in shape.

With its anterior sections, the left fibrous ring is attached to the aortic root, forming triangular connective tissue plates around its posterior periphery - the right and left fibrous triangles, trigonum fibrosum dextrum et trigonum fibrosum sinistrum.

The right and left fibrous rings are interconnected into a common plate, which completely, with the exception of a small area, isolates the muscles of the atria from the muscles of the ventricles. In the middle of the fibrous plate connecting the rings there is a hole through which the muscles of the atria are connected to the muscles of the ventricles through the atrioventricular bundle.

In the circumference of the openings of the aorta and the pulmonary trunk, there are also interconnected fibrous rings; the aortic ring is connected to the fibrous rings of the atrioventricular orifices.

The muscular layer of the atria. In the walls of the atria, two muscle layers are distinguished: superficial and deep.

The superficial layer is common to both atria and consists of muscle bundles that run mainly in the transverse direction. They are more pronounced on the anterior surface of the atria, forming here a relatively wide muscle layer in the form of a horizontally located inter-auricular bundle, passing to the inner surface of both ears.

On the posterior surface of the atria, the muscle bundles of the superficial layer are partially woven into the posterior sections of the septum. On the posterior surface of the heart, between the bundles of the superficial layer of muscles, there is a recess covered with epicardium, bounded by the mouth of the inferior vena cava, the projection of the atrial septum, and the mouth of the venous sinus. In this area, the atrial septum includes nerve trunks that innervate the atrial septum and the ventricular septum - the atrioventricular bundle.

The deep layer of muscles of the right and left atria is not common to both atria. It distinguishes between circular and vertical muscle bundles.

Circular muscle bundles lie in large numbers in the right atrium. They are located mainly around the openings of the vena cava, passing to their walls, around the coronary sinus of the heart, at the mouth of the right ear and at the edge of the oval fossa: in the left atrium they lie mainly around the openings of the four pulmonary veins and at the beginning of the left ear.

Vertical muscle bundles are located perpendicular to the fibrous rings of the atrioventricular holes, attaching to them with their ends. Part of the vertical muscle bundles enters the thickness of the cusps of the atrioventricular valves.

Comb muscles, mm. pectinati. also formed by deep layer bundles. They are most developed on the inner surface of the anterior right wall of the cavity of the right atrium, as well as the right and left ears; in the left atrium they are less pronounced. In the intervals between the comb muscles, the wall of the atria and ears is especially thinned.

On the inner surface of both ears there are short and thin bundles, the so-called fleshy trabeculae, trabeculae carneae. Crossing in different directions, they form a very thin loop-like network.

The muscular layer of the ventricles. In the muscular membrane (myocardium) there are three muscle layers: outer, middle and deep. The outer and deep layers, passing from one ventricle to another, are common in both ventricles; the middle one, although connected with the other two layers, surrounds each ventricle separately.

The outer, relatively thin layer consists of oblique, partly rounded, partly flattened bundles. The bundles of the outer layer begin at the base of the heart from the fibrous rings of both ventricles and partly from the roots of the pulmonary trunk and aorta. On the sternocostal (anterior) surface of the heart, the external bundles go from right to left, and along the diaphragmatic (lower) surface - from left to right. At the top of the left ventricle, those and other bundles of the outer layer form the so-called curl of the heart, vortex cordis, and penetrate into the depths of the walls of the heart, passing into the deep muscle layer.

The deep layer consists of bundles that rise from the top of the heart to its base. They are cylindrical, and some of the bundles are oval, split many times and reconnect, forming loops of various sizes. The shorter of these bundles do not reach the base of the heart, they are directed obliquely from one wall of the heart to another in the form of fleshy trabeculae. Only the interventricular septum immediately below the arterial openings is devoid of these crossbars.

A number of such short, but more powerful muscle bundles, partly connected with both the middle and outer layers, protrude freely into the cavity of the ventricles, forming cone-shaped papillary muscles of various sizes.

Papillary muscles with tendinous chords hold the valve leaflets when they are slammed by the blood flow from the contracted ventricles (during systole) to the relaxed atria (during diastole). Encountering obstacles from the valves, the blood rushes not into the atria, but into the openings of the aorta and pulmonary trunk, the semilunar valves of which are pressed by the blood flow against the walls of these vessels and thereby leave the lumen of the vessels open.

Located between the outer and deep muscle layers, the middle layer forms a number of well-defined circular bundles in the walls of each ventricle. The middle layer is more developed in the left ventricle, so the walls of the left ventricle are much thicker than the walls of the right. The bundles of the middle muscle layer of the right ventricle are flattened and have an almost transverse and somewhat oblique direction from the base of the heart to the apex.

The interventricular septum, septum interventriculare, is formed by all three muscle layers of both ventricles, but there are more muscle layers of the left ventricle. The thickness of the septum reaches 10-11 mm, somewhat inferior to the thickness of the wall of the left ventricle. The interventricular septum is convex towards the cavity of the right ventricle and represents a well-developed muscle layer for 4/5. This much larger part of the interventricular septum is called the muscular part, pars muscularis.

The upper (1/5) part of the interventricular septum is the membranous part, pars membranacea. The septal leaflet of the right atrioventricular valve is attached to the membranous part.

The structure of the walls of the heart

The walls of the heart consist of 3 shells: the inner one - the endocardium, the middle one - the myocardium and the outer one - the epicardium, which is the visceral layer of the pericardium, pericardium.

The thickness of the walls of the heart is formed mainly by the middle shell, myocardium, myocardium, consisting of cardiac striated muscle tissue. outer shell,

epicardium, represents the serous cover. The inner shell, endocardium, endocardium, lines the cavity of the heart.

Myocardium, myocardium, or muscle tissue of the heart, although it has a transverse striation, differs from skeletal muscles in that it does not consist of separate multinuclear

fibers, but is a network of mononuclear cells - cardiomyocytes. In the muscles of the heart, two sections are distinguished: the muscle layers of the atrium and the muscle layers

ventricles. The fibers of both start from two fibrous rings - anuli fibrosi, of which one surrounds the ostium atrioventriculare dextrum, the other - ostium atrioventriculare

sinistrum. Since the fibers of one department, as a rule, do not pass into the fibers of another, the result is the possibility of contraction of the atria separately from the ventricles.

In the atria, superficial and deep muscle layers are distinguished: the superficial one consists of circular or transversely arranged fibers, the deep one consists of longitudinal,

which, with their ends, start from the fibrous rings and loop around the atrium. Along the circumference of large venous trunks that flow into the atria, there are

circular fibers covering them, like sphincters. The fibers of the superficial layer cover both atria, the deep ones belong separately to each atrium.

The muscles of the ventricles are even more complex. Three layers can be distinguished in it: a thin surface layer is composed of longitudinal fibers that start from the right

fibrous ring and go obliquely down, passing to the left ventricle; at the top of the heart they form a curl, vortex cordis, bending here in a loop-like manner in depth and

making up the inner longitudinal layer, the fibers of which are attached to the fibrous rings with their upper ends. The fibers of the middle layer are located between

longitudinal external and internal, go more or less circularly, and, unlike the surface layer, they do not pass from one ventricle to another, but are

independent for each ventricle. An important role in the rhythmic work of the heart and in the coordination of the activity of the muscles of individual chambers of the heart is played by the so-called

conducting system of the heart. Although the muscles of the atria are separated from the muscles of the ventricles by fibrous rings, however, there is a connection between them through

conduction system, which is a complex neuromuscular formation. The muscle fibers that make up it (conductive fibers) have a special structure: they

cells are poor in myofibrils and rich in sarcoplasm, so they are lighter. They are sometimes visible to the naked eye in the form of light-colored threads and represent less

differentiated part of the original syncytium, although they are larger than the usual muscle fibers of the heart. In a conducting system, nodes and bundles are distinguished.

1. The sinoatrial node, nodus sinuatrialis, is located in the section of the wall of the right atrium corresponding to the sinus venosus of cold-blooded animals (in sulcus terminalis,

between the superior vena cava and the right ear). It is associated with the muscles of the atria and is important for their rhythmic contraction.

2. The atrioventricular node, nodus atrioventricularis, is located in the wall of the right atrium, near the cuspis septalis of the tricuspid valve. node fibers,

directly connected with the muscles of the atrium, continue into the septum between the ventricles in the form of an atrioventricular bundle, fasciculus atrioventricularis

(bundle of His). In the septum of the ventricles, the bundle is divided into two legs - crus dextrum et sinistrum, which go into the walls of the corresponding ventricles and branch under the endocardium into their

musculature. The atrioventricular bundle is very important for the work of the heart, since it transmits a wave of contraction from the atria to the ventricles,

due to which the regulation of the rhythm of systole - atria and ventricles is established.

Therefore, the atria are connected to each other by the sinoatrial node, and the atria and ventricles are connected by the atrioventricular bundle. Usually irritation from

of the right atrium will be transmitted from the sinoatrial node to the atrioventricular node, and from it along the atrioventricular bundle to both ventricles.

The epicardium, epicardium, covers the outside of the myocardium and is a normal serous membrane lined on the free surface with mesothelium.

Endocardium, endocardium, lines the inner surface of the cavities of the heart. It, in turn, consists of a layer of connective tissue with a large number of elastic

fibers and smooth muscle cells, from another layer of connective tissue located externally with an admixture of elastic fibers and from the internal endothelial

layer, how the endocardium differs from the epicardium. The endocardium in its origin corresponds to the vascular wall, and the listed layers of it correspond to the 3 membranes of the vessels. All cordial

valves represent folds (duplicatures) of the endocardium.

The described features of the structure of the heart determine the features of its vessels, which form, as it were, a separate circle of blood circulation - the heart (third circle).

Arteries of the heart - aa. coronariae dextra et sinistra, the coronary arteries, right and left, start from the bulbus aortae below the upper edges of the semilunar valves. Therefore, in

during systole, the entrance to the coronary arteries is covered by valves, and the arteries themselves are compressed by the contracted muscle of the heart. As a result, during systole, the blood supply

heart decreases: blood enters the coronary arteries during diastole, when the inlets of these arteries, located at the aortic mouth, are not closed by the semilunar

Right coronary artery, a. coronaria dextra, exits the aorta, respectively, the right semilunar valve and lies between the aorta and the right atrial appendage, outwards

from which it goes around the right edge of the heart along the coronal sulcus and passes to its posterior surface. Here it continues into the interventricular branch, r. interventricularis

posterior. The latter descends along the posterior interventricular sulcus to the apex of the heart, where it anastomoses with a branch of the left coronary artery.

The branches of the right coronary artery vascularize: the right atrium, part of the anterior wall and the entire back wall right ventricle, a small area of the posterior wall

left ventricle, atrial septum, posterior third of the interventricular septum, papillary muscles of the right ventricle and posterior papillary muscle of the left

The left coronary artery, a. coronaria sinistra, leaving the aorta at its left semilunar valve, also lies in the coronary sulcus anterior to the left atrium. Between

pulmonary trunk and left ear, it gives two branches: a thinner anterior, interventricular, ramus interventricularis anterior, and a larger left, envelope, ramus

The first descends along the anterior interventricular sulcus to the apex of the heart, where it anastomoses with a branch of the right coronary artery. The second, continuing the main

the trunk of the left coronary artery, goes around the heart on the left side along the coronary groove and also connects to the right coronary artery. As a result, throughout the coronal sulcus

an arterial ring is formed, located in a horizontal plane, from which branches depart perpendicularly to the heart. The ring is functional

device for collateral circulation of the heart. Branches of the left coronary artery vascularize the left atrium, the entire anterior wall and most of the posterior

the walls of the left ventricle, part of the anterior wall of the right ventricle, the anterior 2/3 of the interventricular septum and the anterior papillary muscle of the left ventricle.

Various variants of the development of the coronary arteries are observed, as a result of which there are various ratios of the blood supply pools. From this point of view, one distinguishes

three forms of blood supply to the heart: uniform with the same development of both coronary arteries, left vein and right vein.

In addition to the coronary arteries, "additional" arteries approach the heart from the bronchial arteries, from the lower surface of the aortic arch near the arterial ligament, which is important

take into account so as not to damage them during operations on the lungs and esophagus and thus not worsen the blood supply to the heart.

Intraorganic arteries of the heart: branches of the atria (rr. atriales) and their ears (rr.

auriculares), branches of the ventricles (rr. ventriculares), septal branches (rr. septales anteriores et posteriores). Penetrating into the thickness of the myocardium, they branch out accordingly

the number, location and arrangement of its layers: first in the outer layer, then in the middle (in the ventricles) and finally in the inner, after which they penetrate into the papillary muscles (aa.

papillares) and even into the atrioventricular valves. Intramuscular arteries in each layer follow the course of the muscle bundles and anastomose in all layers and departments

Some of these arteries have a highly developed layer of involuntary muscles in their wall, with the contraction of which the lumen of the vessel is completely closed,

why these arteries are called "closing". A temporary spasm of the "closing" arteries can lead to a cessation of blood flow to this area of the heart muscle and

cause myocardial infarction.

The veins of the heart do not open into the vena cava, but directly into the cavity of the heart.

Intramuscular veins are located in all layers of the myocardium and, accompanying the arteries, correspond to the course of the muscle bundles. Small arteries (up to the 3rd order) are accompanied by

double veins, large - single. Venous outflow goes in three ways: 1) into the coronary sinus, 2) into the anterior veins of the heart and 3) into the smallest veins that flow into

directly to the right side of the heart. There are more of these veins in the right half of the heart than in the left, and therefore the coronary veins are more developed on the left.

The predominance of the smallest veins in the walls of the right ventricle with a small outflow through the system of the veins of the coronary sinus indicates that they play an important role in

redistribution of venous blood in the region of the heart.

1. Veins of the coronary sinus system, sinus coronarius cordis. It is a remnant of the left common cardinal vein and lies in the posterior coronary sulcus of the heart,

between the left atrium and left ventricle. With its right, thicker end, it flows into the right atrium near the septum between the ventricles, between the valve

inferior vena cava and atrial septum. The following veins flow into the sinus coronarius:

a)v. cordis magna, starting at the apex of the heart, lifts it along the anterior interventricular sulcus of the heart, turns to the left and, rounding the left side

heart, continues in sinus coronarius;

b) v. posterior ventriculi sinistri - one or more venous trunks on the posterior surface of the left ventricle, flowing into the sinus coronarius or v. cordis magna;

c) v. obliqua atrii sinistri - a small branch located on the posterior surface of the left atrium (the remnant of the germinal v. cava superior sinistra); it starts at

a pericardial fold containing a connective tissue cord, plica venae cavae sinistrae, also representing the remainder of the left vena cava;

d) v. cordis media lies in the posterior interventricular sulcus of the heart and, having reached the transverse sulcus, flows into the sinus coronarius;

e) v. cordis parva - a thin branch located in the right half of the transverse sulcus of the heart and usually flows into v. cordis media where this vein reaches

2. Anterior veins of the heart, vv. cordis anteriores, - small veins, located on the anterior surface of the right ventricle and flow directly into the cavity of the right

3. The smallest veins of the heart, vv. cordis minimae, - very small venous trunks, do not appear on the surface of the heart, but, having gathered from the capillaries, flow directly into

atrial cavity and, to a lesser extent, the ventricles.

There are 3 networks of lymphatic capillaries in the heart: under the endocardium, inside the myocardium and under the epicardium. Among the efferent vessels, two main ones are formed.

lymphatic collectors of the heart. The right collector arises at the beginning of the posterior interventricular sulcus; it receives lymph from the right ventricle and atrium and reaches

left upper anterior nodes of the mediastinum, lying on the aortic arch near the beginning of the left common carotid artery.

The left collector is formed in the coronary sulcus at the left edge of the pulmonary trunk, where it receives vessels that carry lymph from the left atrium, left ventricle and

partially from the anterior surface of the right ventricle; then it goes to the tracheobronchial or tracheal nodes or to the nodes of the root of the left lung.

The nerves that provide innervation to the cardiac muscles, which have a special structure and function, are complex and form numerous plexuses.

All nervous system consists of: 1) suitable trunks, 2) extracardiac plexuses, 3) plexuses in the heart itself and 4) nodal fields associated with the plexus.

Functionally, the nerves of the heart are divided into 4 types (I.P. Pavlov): slowing down and accelerating, weakening and strengthening. Morphologically, these nerves are part of n.

vagus and branches of truncus sympathicus. Sympathetic nerves (mainly postganglionic fibers) arise from the upper cervical and five upper thoracic sympathetic nerves.

nodes: n. cardiacus cervicalis superior - from ganglion cervicale superius, n. cardiacus cervicalis medius, - from ganglion cervicale medium, n.cardiacus cervicalis inferior - from ganglion

cervicale inferius or ganglion cervicothoracicum and nn.cardiaci thoracici from the thoracic nodes of the sympathetic trunk.

heart branches vagus nerve start from its cervical (rami cardiaci cervicalis superiores), chest (rami cardiaci thoracici) and from n. laryngeus recurrens

vagi (rami cardiaci cervicales inferiores). The nerves approaching the heart are divided into two groups - superficial and deep. The surface group is adjacent in the upper section to

sleepy and subclavian arteries, in the lower - to the aorta and pulmonary trunk. The deep group, composed mainly of the branches of the vagus nerve, lies on the anterior

surface of the lower third of the trachea. These branches are in contact with lymph nodes located in the trachea, and with an increase in nodes, for example, with tuberculosis

lungs, can be compressed by them, which leads to a change in the rhythm of the heart. Two nerve plexuses are formed from the listed sources:

1) superficial, plexus cardiacus superficialis, between the aortic arch (under it) and the bifurcation of the pulmonary trunk;

2) deep, plexus cardiacus profundus, between the aortic arch (behind it)

and tracheal bifurcation.

These plexuses continue into the plexus coronarius dexter et sinister, surrounding the vessels of the same name, and also into the plexus located between the epicardium and myocardium. From

of the last plexus, the intraorgan branching of the nerves departs. The plexuses contain numerous groups of ganglion cells, nerve nodes.

Afferent fibers start from receptors and go together with efferent fibers as part of the vagus and sympathetic nerves.

133. Layers of the wall of the heart, their functions.

The heart, cor (Greek cardia), is a hollow organ, the walls of which consist of three layers - inner, middle, outer.

Middle shell, myocardium, myocardium is formed by striated muscle cells (cardiomyocytes). Provides contraction of the atria and ventricles.

outer shell, epicardium, epicardium is represented by a serous membrane, which is the visceral sheet of the pericardium. The shell provides free displacement of the heart during its contraction.

134. The degree of expression of the muscle layer in the chambers of the heart.

135. Features of the structure of the myocardium of the ventricles and atria.

In the atria, the myocardium consists of two layers: superficial- common to both ventricles and deep- separate for each of them.

In the ventricles, the myocardium consists of three layers: external (surface), middle and internal (deep).

The outer and inner layers are common to both ventricles, while the middle layer is separate for each ventricle. The muscle fibers of the atria and ventricles are isolated from each other.

Derivatives of the deep layer of the ventricular myocardium are papillary muscles and fleshy trabeculae.

Derivatives of the outer layer of the atrial myocardium are the pectinus muscles.

136. Large and small circles of blood circulation, their functions.

137. Heart valves, their functions.

The heart has four valves: two valvular and two semilunar.

Right atrioventricular (tricuspid) valve located between the right atrium and ventricle.

Left atrioventricular (mitral) valve located between the left atrium and ventricle.

Pulmonary valve, valva trunci pulmonalis is located within the base of the pulmonary trunk.

aortic valve, valva aortae is located within the base of the aorta.

On this topic...

The walls of the heart are made up of three layers:

endocardium- thin inner layer;
myocardium- thick muscle layer;
epicardium- a thin outer layer, which is the visceral sheet of the pericardium - the serous membrane of the heart (heart sac).

Endocardium lines the cavity of the heart from the inside, exactly repeating its complex relief. The endocardium is formed by a single layer of flat polygonal endotheliocytes located on a thin basement membrane.

Myocardium It is formed by cardiac striated muscle tissue and consists of cardiac myocytes interconnected by a large number of jumpers, with the help of which they are connected into muscle complexes that form a narrow-loop network. Such a muscular network provides rhythmic contraction of the atria and ventricles. At the atria, the thickness of the myocardium is the smallest; in the left ventricle - the greatest.

Myocardium of the ventricles consists of three different layers: outer, middle and inner. In the outer layer, the muscle bundles are oriented obliquely, starting from the fibrous rings, continuing down to the apex of the heart, where they form a heart curl. The inner layer of the myocardium consists of longitudinally arranged muscle bundles. Due to this layer, papillary muscles and trabeculae are formed. The outer and inner layers are common to both ventricles. The middle layer is formed by circular muscle bundles, separate for each ventricle.

epicardium It is built according to the type of serous membranes and consists of a thin plate of connective tissue covered with mesothelium. The epicardium covers the heart, the initial sections of the ascending aorta and pulmonary trunk, the final sections of the caval and pulmonary veins.

Atrial and ventricular myocardium

atrial myocardium;
left ear;
ventricular myocardium;
left ventricle;
anterior interventricular sulcus;
right ventricle;
pulmonary trunk;
coronal furrow;
right atrium;
superior vena cava;
left atrium;
left pulmonary veins.

wall thick guts they form a serous membrane, tunica serosa, a subserous layer, tela subserosa, a muscular membrane, tunica muscularis, a submucosal layer, tela submucosa, and a mucous membrane, tunica mucosa. Serous membrane, tunica serosa, refers to individual parts differently thick guts.

The appendix lies intraperitoneally. His mesentery, mesenteriolum processus vermiformis (Fig. 535, 539), does not prevent the displacement of the appendix, due to which its position is unstable. More often it is directed downward. Bending over m. psoas major and linea innominata, with its blind end appendix directed into the pelvic cavity. The appendix can be located medially or laterally, in front of or behind the blind guts, moving in all directions near one point - the place of its departure from the blind guts.

The ratio of the serous cover to the intestinum caecum varies: the caecum may lie meso- or intraperitoneally. Sometimes the caecum has a mesentery, the presence of which causes some mobility guts(caecum mobile). Colon ascendens lies mesoperitoneally: the posterior surface of the ascending part thick guts, devoid of a peritoneal cover, is turned towards the retroperitoneal tissue.

Colon transversum lies intraperitoneally. It has a fairly long mesentery of the transverse colon guts, mesocolon transversum (Fig. 564, 565), which fixes the intestine to the posterior abdominal wall in the transverse direction.

Colon descendens, like colon ascendens, is located mesoperitoneally.

Colon sigmoideum lies intraperitoneally and has a fairly long S-shaped mesentery. guts, mesosigmoideum (Fig. 565, 569).

Initial part of the line guts lies intraperitoneally, having a straight mesentery guts, mesorectum (Fig. 574). Middle divisions of the straight line guts located mesoperitoneally, and the final part - extraperitoneally.

All over thick guts there are flat, freely hanging in abdominal cavity processes of the serous cover - accessory glands, appendices epiploicae (Fig. 536), with fiber embedded inside them. The subserous layer, tela subserosa, in the form of an insignificant layer of fiber, is present only in the parts covered with the peritoneum thick guts.

The muscular membrane, tunica muscularis, consists of muscle bundles, located in two layers - the outer longitudinal, stratum longitudinale, and the inner, circular, stratum circulare.

Longitudinal layer, stratum longitudinale, throughout thick guts, with the exception of a straight line, is located unevenly around the circumference guts. Longitudinal bundles are concentrated into three longitudinal, narrow muscle strands. They are clearly visible on the surface. guts in the form of three ribbon-like smooth strands, called lenuiolzh, taeniaecoli. One cord runs along the front surface guts; it gets the name of the free tape, taenia libera, the other on the posterior inner surface - the mesenteric tape, taenia mesocolica, and the third - on the posterior outer surface guts-salyshkovy tape, taenia omentalis (Fig. 535, 536).

Plots of steak thick guts, located between these strands, have the form of a series of pocket-shaped protrusions - protrusions thick guts, haustra coli (Fig. 536), alternating with interceptions. Haustra coli, taeniaecoli and appendices epiploicac are features that distinguish the outer surface thick guts from the outer surface of the thin guts.

The circular layer, stratum circulare, is the inner muscle layer. Muscle bundles of this layer in the final part of the straight line guts form an internal constrictor of the anus, t. sphincter ani internus (Fig. 541, 542), consisting of smooth muscle fibers.

Somewhat lower, in the perineal region, the anus is surrounded by a layer of striated muscle fibers that form the external constrictor of the anus, i.e. sphincter ani externus (Fig. 537, 541, 542).

To the end of the line guts, in addition, bundles of the muscle that lifts anus, t. levator ani (Fig. 541, 542).

Submucosal layer, tela submucosa - a layer of loose fiber with a large number of vessels and nerves. Particularly rich in venous vessels is the submucosal layer of the final sections of the straight line. guts, where three rectal venous plexuses lie, plexus haemorrhoidales - superior, medius et inferior.

The mucous membrane, tunica mucosa, has a large number of folds. At the junction of the thin guts a fold is located in the thick, called the valve thick guts, valvula coli (Bauhini). It consists of two lips, upper and lower, labium superius et infetius (Fig. 538, 539), from which a fold is stretched on both sides - the flap frenulum thick guts, frenulum valmlae coli.

At the mouth of the appendix there is a fold of the mucous membrane of the flap of the appendix, valvula processus vermiformis (Herlach) (Fig. 539). The mucous membrane of all departments thick guts, with the exception of the straight line, has fairly high semilunar folds, plicae semilunares coli (Fig. 539). On the mucous membrane of the straight guts there are three high transverse folds, plicae transversales recti (Fig. 541). The upper and lower folds lie on the left semicircle guts, middle, most developed, the so-called plica transversa Kohlrauschi - on the right semicircle guts. The circular muscle layer, well developed in the region of this fold, is called "!, Sphincter ani tertius (Nelaton), (Fig. 541).

At the end of the straight line guts there are 8-10 folds of the mucous membrane - straight rollers guts, columnaerectales (Morgagnii) (Fig. 541, 542), running in the longitudinal direction. The recesses of the mucous membrane between the lower sections of these folds are called the sinuses of the visible guts, sinus rectales.

The area of the mucous membrane located below the sinus rectales, on the border between them and the skin, is called the rectal ring, ap-nulus haemorrhoidalis. In the submucosal layer of this area, the lower rectal venous plexus and a small amount of the gland are laid.

Throughout the mucosa thick guts opens a large number of intestinal crypts (glands), glandulae intestinales (Liberkuhni), and there are also lymphatic nodules, noduli lymphatici solitarii. On the mucous membrane of the appendix, there is a large accumulation of lymphoid tissue in the form of single follicular formations. mucous membrane thick guts, Unlike the thin mucous membrane, it has no villi.

The muscular layer of the wall of the heart. The structure of the walls of the heart

1 Heart layers

2 We delve into the outer layer

3 Why does the heart need a bag?

4 When the pericardium "sick"

5 Heart injection or pericardial puncture

The structure of the wall of the heart.

The structure of the walls of the heart

The middle layer of the heart wall is made up of

Answers and explanations

133. Layers of the wall of the heart, their functions.

134. The degree of expression of the muscle layer in the chambers of the heart.

135. Features of the structure of the myocardium of the ventricles and atria.

136. Large and small circles of blood circulation, their functions.

137. Heart valves, their functions.

The structure of the wall of the heart

The structure of the wall of the heart

1 Heart layers

2 We delve into the outer layer

3 Why does the heart need a bag?

4 When the pericardium "sick"

5 Heart injection or pericardial puncture

Heart - how does it work?

Some facts about the work of the heart

chambers of the heart

valve apparatus

Layers of the heart wall

Some information about the hydrodynamics of the heart

Phases of the contraction of the heart

How is the heart supplied with blood?

What controls the work of the heart?

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The structure of the walls of the heart

The structure of the wall of the heart

The structure of the walls of the heart

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The structure of the wall of the heart.

The structure of the walls of the heart

133. Layers of the wall of the heart, their functions.

134. The degree of expression of the muscle layer in the chambers of the heart.

135. Features of the structure of the myocardium of the ventricles and atria.

136. Large and small circles of blood circulation, their functions.

137. Heart valves, their functions.

Atrial and ventricular myocardium