Category: Heart anatomy

 

Arteries of the small (pulmonary) circulation. Pulmonary trunk. The pulmonary trunk, truncus pulmonalis, carries venous blood from the right ventricle to the lungs. It is a continuation of the truncus arteriosus and is directed obliquely to the left, crossing the aorta lying behind it. The location of the pulmonary trunk in front of the aorta is explained by the fact that the truncus pulmonalis develops from the ventral part of the truncus arteriosus, and the aorta from the dorsal. Having passed 5 – 6 cm, the pulmonary trunk is divided under the aortic arch at the level of the IV – V thoracic vertebra into two terminal branches – a. pulmonalis dextra and a. pulmonalis sinistra, each going to the corresponding lung. The right and left pulmonary arteries develop from 6 arterial arcs laid in the embryonic life. The right one, longer, passes to the right lung behind aorta ascendens and the superior vena cava, the left one in front of aorta descendens. Passing to the lungs, a. pulmonalis dextra and a. pulmonnalis sinistra are again divided into branches to the corresponding lobes of the lungs and to the pulmonary segments and, accompanying the bronchi, branch into the smallest arteries, arterioles, precapillaries and capillaries. To the site of division, truncus pulmonalis is covered with a leaf of pericardium. From the site of division to the concave side of the aorta, the connective tissue cord stretches – lig. arteriosum, which is obliterated ductus arteriosus.

Pericardium. The structure of the pericardium.

Pericardium, pericardium (in the broad sense of the word), is a closed serous bag, in which two layers are distinguished: external fibrous, pericardium fibrosum, and internal serous, pericardium serosum. The outer fibrous layer passes into the adventitia of large vascular trunks, and is anteriorly attached to the inner surface of the sternum via short connective tissue cords, ligamenta sternope-ricardiaca. The inner serous layer (pericardium serosum), in turn, is divided into 2 sheets: visceral, or the above-mentioned epicardium, and parietal, spliced ​​with the inner surface of pericardium fibrosum and lining it from the inside. Between the visceral and parietal sheets is a slit-like serous pericardial cavity, cavitas pericardialis, containing a small amount of serous fluid, liquor pericardii. On trunks of large vessels, at a close distance from the heart, the visceral and parietal sheets pass directly into each other. The unopened pericardium as a whole has the shape of a cone, the base of which grows together with the centrum tendineum diaphragmatis, and the blunt tip is directed upwards and covers the roots of large vessels. From the sides, the pericardium is adjacent directly to the mediastinal pleura of the one and the other side. With its posterior surface, the pericardial sac fits to the esophagus and descending aorta. The aorta and the pulmonary trunk are surrounded on all sides by a common leaflet of the pericardium. The passage behind the aorta and pulmonary trunk is called the transverse sinus of the pericardium, sinus transversus pericardii. Hollow veins and pulmonary veins are only partially covered with serous leaflets. The space bounded by the inferior vena cava below and to the right, the left pulmonary veins to the left and above, is sinus obliquus pericardii.

The position of the heart. Types of position of the heart. The size of the heart.

The shape and position of the heart depend on the physique, sex, age, various physiological conditions and other factors.

1. Oblique (most common) position of the heart. The cardiovascular shadow has a triangular shape, the “waist” of the heart is weakly expressed. The angle of inclination of the long axis of the heart is 43 – 48 °.
2. The horizontal position of the heart. The silhouette of the cardiovascular shadow occupies an almost horizontal (recumbent) position; tilt angle is 35 – 42 °; “Waist” is pronounced. The length of the heart is reduced, the diameter is enlarged.
3. The vertical position of the heart .. The silhouette of the cardiovascular shadow occupies an almost vertical (standing) position; tilt angle is 49 – 56 °; “Waist” smoothed. The length of the heart is enlarged, the diameter is reduced.

In people of the brachimorphic type with a wide and short rib cage, with a high standing of the diaphragm, the heart as if rises by the diaphragm and lies on it, assuming a horizontal position. In people of the dolichomorphic type with a narrow and long rib cage, with a low standing of the diaphragm, the heart descends, as if drawn out, and takes on a vertical position. In people intermediate between the two extreme body type oblique position of the heart is observed. Thus, the shape and position of the heart can be judged to a certain degree by the nature of the build and the shape of the chest.

Sex differences are that women are more likely to have a horizontal position of the heart than men. The size of the heart depends on gender, age, body weight and height, chest structure, working and living conditions. An increase in the absolute size of the heart as a whole goes along with an increase in height and body weight. A large influence on the size of the heart has the development of muscles. This explains the fact that with the same height and body weight in women, the heart is smaller than in men.

The effect of physical work on the size of the heart is especially evident in the X-ray examination of athletes in whom physical stress is prolonged.

In the study in the left nipple position

In the study in the left nipple position (the subject stands obliquely, adjacent to the screen by the area of ​​the left nipple), four lung fields are visible, separated from each other by the sternum with a cardiovascular shadow and vertebral column: of the lung, 2) retrosternal – between the upper part of the sternum and the anterior contour of the aortic arch, 3) retrocardial – between the posterior contour of the heart and the aorta (“aortic window”) and 4) the retrovertebral field located behind the spinal column .

Anterior, facing the sternum contour of the cardiovascular shadow is formed in the upper part of the right atrium, in the lower part – the right ventricle. The posterior contour of the cardiovascular silhouette facing the spinal column corresponds at the top to the left atrium, at the bottom to the left ventricle. Thus, in this position, each atrium is located above its ventricle, with the right heart (relative to the subject) located on the right and the left on the left, which is easy to remember.

In the study in the right nipple position (the subject stands obliquely, adjacent to the screen by the area of ​​the right nipple), the posterior contour is formed at the top by the ascending aorta, then by the left atrium and at the bottom by the right atrium and inferior vena cava; anterior contour – ascending part of the aorta, pulmonary trunk and left ventricle.

The age-related changes of the x-ray image of the heart are expressed in the following.

In newborns, the cardiovascular shadow occupies almost the middle position; the heart is relatively larger than in adults, mainly due to its right half. The shape of the heart approaches the spherical, the lower arc sharply convex; “Waist” smoothed. With age, there is a relative decrease in the cardiovascular shadow and moving it to the left. In old age, owing to the elongation of the aorta, the waist becomes sharper; the apex of the heart as if bulging, separating from the dome of the diaphragm. A characteristic appearance of the senile heart is lengthening and curvature of the aorta, which in its ascending part projects to the right (forming the bulge of the upper arch of the right contour), and bulging in the arcus aortae to the left (forming the bulge of the upper arc of the left contour).

In the forward position the side contours

In the forward position, the lateral contours of the cardiovascular shadow have two arcs on the right and four on the left. On the right contour, the lower arch is well defined, which corresponds to the right atrium; the upper slightly convex arch is located medially to the lower one and is formed by the ascending part of the aorta and the superior vena cava. This arc is called vascular. Above the vascular arch a small arc is still visible, going up and outwards, towards the clavicle; it corresponds to the brachiocephalic vein. Below the arc of the right atrium forms an acute angle with the diaphragm. In this corner, with a low standing of the diaphragm at the height of a deep breath, one can see a vertical shadow strip that corresponds to the inferior vena cava.

On the left contour, the uppermost (first) arc corresponds to the arc and the beginning of the descending part of the aorta, the second to the pulmonary trunk, the third to the left ear and the fourth to the left ventricle. The left atrium, located for the most part on the posterior surface, is not kraeobrazuyuschy with dorsoventral rays and therefore not visible in the anterior position. For the same reason, the right ventricle located on the anterior surface is not contoured, which also merges with the shadow of the liver and diaphragm below. The place of transition of the left ventricular arch into the lower contour of the cardiac silhouette is marked radiographically as the apex of the heart.

In the area of ​​the second and third arcs, the left contour of the heart silhouette has the character of indentation or interception, which is called the “waist” of the heart. The latter separates the heart from the vessels connected with it, which constitute the so-called vascular bundle.

Turning the subject around the vertical axis, one can see in oblique positions those segments that are not visible in the anterior position (right ventricle, left atrium, most of the left ventricle). The most widely used are the so-called first (right nipple) and second (left nipple) oblique positions.

X-ray anatomy of the heart.

X-ray examination of the heart of a living person is carried out mainly by chest X-ray in its various positions. Due to this, it is possible to inspect the heart from all sides and get an idea of ​​its shape, size and position, as well as the state of its departments (ventricles and atria) and the large vessels associated with them (aorta, pulmonary artery, vena cava).

The main position for the study is the anterior position of the subject (the course of the rays is sagittal, dorsoventral). In this position, two bright lung fields are visible, between which there is an intense dark, so-called middle, shadow. It is formed by the shadows of the thoracic spinal column and the sternum layered on top of each other and the heart, large vessels and organs of the posterior mediastinum located between them. However, this median shadow is considered only as a silhouette of the heart and large vessels, because the other formations mentioned (spine, sternum, etc.) usually do not appear within the limits of the cardiovascular shadow. The latter, in normal cases, both on the right and on the left, goes beyond the edges of the spinal column and the sternum, which become visible in the anterior position only in pathological cases (curvature of the spine, displacement of the cardiovascular shadow, etc.).

The above-mentioned median shadow has in the upper part a form of a wide band, which expands downwards and to the left in the form of an irregular triangle, with the base facing downwards. The lateral contours of this shadow have the form of protrusions, separated from each other by impressions. These tabs are called arcs. They correspond to those parts of the heart and the large vessels connected with it, which form the edges of the cardiovascular silhouette.

Heart topography.

The heart is located in the anterior mediastinum asymmetrically. Most of it is to the left of the median line, only the right atrium and both vena cava remain to the right. The long axis of the heart is located obliquely from top to bottom, from right to left, back to front, forming an angle of approximately 40 ° with the axis of the whole body. At the same time, the heart is turned in such a way that its right venous section lies more anteriorly, the left arterial section lies posteriorly.

The heart together with the pericardium in most of its anterior surface (facies sternocostalis) is covered with lungs, the anterior edges of which, together with the corresponding parts of both pleura, coming in front of the heart, separate it from the anterior chest wall, except for one place where the anterior surface of the heart is through the pericardium adjacent to the sternum and cartilage of the V and VI ribs. The borders of the heart are projected on the chest wall as follows. The push of the apex of the heart can be palpated 1 cm internally from linea mamillaris sinistra in the fifth left intercostal space. The upper limit of the cardiac projection is at the level of the upper edge of the third costal cartilage. The right border of the heart extends 2–3 cm to the right of the right edge of the sternum, from the third to the fifth rib; the lower boundary goes transversely from the V right costal cartilage to the apex of the heart, the left border from the cartilage of the III rib to the apex of the heart.

The ventricular outlets (aorta and pulmonary trunk) lie on the level III of the left costal cartilage; pulmonary trunk (ostium trunci pulmonalis) – at the sternal end of this cartilage, aorta (ostium aortae) – behind the sternum somewhat to the right. Both ostia atrioventricularia are projected on a straight line running along the sternum from the third left to the fifth right intercostal space.

During auscultation of the heart (listening to the tones of the valves using a phonendoscope), the tones of the heart valves are heard in certain places: mitral – at the apex of the heart; tricuspid – on the sternum to the right against the V costal cartilage; the tone of the aorta valves – at the edge of the sternum in the second intercostal space on the right; the tone of the pulmonary valves – in the second intercostal space to the left of the sternum.

Nerves of the heart. Innervation of the heart.

The nerves that provide innervation of the cardiac muscles, which have a special structure and function, are complex and form numerous plexuses. The entire nervous system is composed of:

1) suitable trunks,

2) extracardiac plexuses,

3) plexuses in the heart, and

4) nodal fields associated with the plexus.

Functionally, the nerves of the heart are divided into 4 types (I. P. Pavlov): slowing and accelerating, weakening and strengthening. Morphologically, these nerves are part of n. vagus and truncus sympathicus branches. The sympathetic nerves (mainly postganglionic fibers) extend from the three upper cervical and five upper thoracic sympathetic ganglions: 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 chest nodes of the sympathetic trunk.

The cardiac branches of the vagus nerve begin from its cervical (rami cardiaci cervicales superiores), thoracic (rami cardiaci thoracici) and from n. laryngeus recurrens vagi (rami cardiaci cervicales inferiores). Nerves suitable to the heart are composed of two groups – superficial and deep. In the upper part, the superficial group is adjacent to the carotid and subclavian arteries, and in the lower part, 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 the lymph nodes located in the trachea, and with an increase in nodes, such as pulmonary tuberculosis, they can be compressed by them, which leads to a change in heart rhythm. From these sources, two nerve plexuses are formed:

1) superficial, plexus cardiacus superficialis, between the aortic arch (under it) and the pulmonary bifurcation;
2) deep, plexus cardiacus profundus, between the aortic arch (behind it) and the trachea bifurcation.

These plexuses continue in the plexus coronarius dexter et sinister, surrounding the somatic vessels, as well as in the plexus located between the epicardium and myocardium. Intraorganic branching of the nerves depart from the last plexus. The plexus contains numerous groups of ganglion cells, nerve nodes.

Afferent fibers begin from receptors and go along with efferent ones in the composition of the vagus and sympathetic nerves.

Veins of the heart. Lymphatic system of the heart.

The veins of the heart do not open into the hollow veins, 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 follows three paths:
1) into the coronary sinus, 2) into the anterior veins of the heart, and 3) into the smallest veins that flow directly into the right side of the heart. In the right half of the heart of these veins more than in the left, in connection with which 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 venous sinus system indicates that they play an important role in the redistribution of venous blood in the region of the heart.

1. Veins of the coronary sinus system, sinus coronarius cordis. It is the remnant of the left common cardinal vein and lies in the posterior part of the coronary furrow of the heart, between the left atrium and the left ventricle. With its right, thicker end, it flows into the right atrium near the septum between the ventricles, between the valve of the inferior vena cava and the atrium septum. The following veins flow into sinus coronarius: a) v. cordis magna, starting at the apex of the heart, rises along the anterior interventricular sulcus of the heart, turns to the left and, rounding the left side of the heart, continues into 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 (remnant embryonic v. cava superior sinistra); it begins in the pericardial fold, enclosing the connective tissue strand, 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, reaching the transverse sulcus, flows into the sinus coronarius; e) v. cordis parva is a thin branch located in the right half of the transverse sulcus of the heart and usually flowing into the v. cordis media in the place where this vein reaches the transverse sulcus.

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

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 capillaries, flow directly into the atrial cavities and to a lesser extent the ventricles.

In the heart, there are 3 networks of lymphatic capillaries: under the endocardium, inside the myocardium and under the epicardium. Among the receptacles, two main lymphatic collectors of the heart are formed. The right collector occurs at the beginning of the posterior interventricular sulcus; it takes the lymph from the right ventricle and the atrium and reaches the 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 the lymph from the left atrium, the left ventricle and partly 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.

Intraorganic arteries of the heart

The first one descends along the anterior interventricular sulcus to the apex of the heart, where it anastomoses with the branch of the right coronary artery. The second, continuing the main trunk of the left coronary artery, bends around the coronary sulcus the heart on the left side and also connects to the right coronary artery. As a result, an arterial ring located in the horizontal plane is formed along the entire coronary sulcus, from which the branches go to the heart perpendicularly. The ring is a functional device for the collateral circulation of the heart. The branches of the left coronary artery vascularize the left, atrium, the entire anterior wall and most of the posterior wall of the left ventricle, part of the anterior wall of the right ventricle, anterior 2/3 of the interventricular septum and the anterior papillary muscle of the left ventricle.

Different variants of the development of coronary arteries are observed, as a result of which there are various ratios of blood supply pools. From this point of view, there are three forms of blood supply to the heart: uniform, with the same development of both coronary arteries, left-handed and right-handed. In addition to the coronary arteries, “additional” arteries from the bronchial arteries, from the lower surface of the aortic arch near the arterial ligament, approach the heart, which is important to take into account in order not to damage them during operations on the lungs and esophagus and not to impair the blood supply to the heart.

The branches of the atria (rr. Atriales) and their ears (rr. Auriculares), the branches of the ventricles (rr. Ventriculares), and the partition walls (rr. Septales anteriores et posteriores) depart from the trunks of the coronary arteries and their large branches, respectively. Having infiltrated into the myocardium, they branch out according to the number, location and arrangement of its layers: first in the outer layer, then on average (in the ventricles) and finally in the inner, then penetrate the papillary muscles (aa. Papillares) and even in the atrial ventricular valves The intramuscular arteries in each layer follow the course of the muscle bundles and anastomose in all layers and parts of the heart.

Some of these arteries have a highly developed layer of involuntary muscles in their walls, with their reduction, a complete closure of the vessel lumen occurs, which is why these arteries are called “closing”. A temporary spasm of the “closure” arteries may result in cessation of blood flow to a given area of ​​the heart muscle and cause myocardial infarction.