Heart 10-2 (1).ppt
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The document provides details on the anatomy of the heart, including its chambers, valves, blood vessels, and conducting system. Some key points: - The heart has four chambers - two atria and two ventricles. It is located slightly left of center in the chest. - The right side receives deoxygenated blood from the body and pumps it to the lungs. The left side receives oxygenated blood from the lungs and pumps it out to the body. - Valves separate the chambers and ensure one-way blood flow. The septum divides the left and right sides. - The conducting system generates electrical signals that coordinate rhythmic contractions of the atria and ventricles.
Heart 10-2 (1).ppt
- 1. THE HEART, COR Synonym ‘cardia’ gives rise to ‘cardiology’, ‘electrocardiography’ and other medical terms. The heart, cor is the central circulatory organ. It occupies the middle division of inferior mediastinum yet it is dislocated leftwards so that the two thirds are found to the left from the median line and the rest — to the right. The axis of heart runs from superior to inferior, posterior to anterior right to left. The mart sizes 14*10*7 cm and weighs about 250-300 grams. -
- 2. The parts, surfaces and borders of heart: The heart appears as flattened conic body. The external features distinguishable are the Base Apex • the base of heart, basis cordis is the upper wider portion of heart. It is directed superiorly, posteriorly and rightwards. The base attaches to large blood vessels; • the apex of heart, apex cordis is the lower narrowed and rounded portion directed inferiorly and leftwards. To the right from the apex one can distinguish a small notch of cardiac apex, incisura apicis cordis; • the anterior (sternocostal) surface, facies anterior (sternocostalis) slightly convex, it is directed anteriorly, superiorly and leftwards; • the diaphragmatic (inferior) surface, facies diaphragmatica (inferior)1 is directed inferiorly, posteriorly and rightwards; this surface adheres to the diaphragm; • the left and light pulmonary surfaces, facies pulmonalis dextra et sinistra face the respective lungs. • the posterior surface, facies vertebralis (posterior).
- 3. • the right border, margo dexter a sharp border that delimits the sur- faces on the right; the border is directed inferiorly and rightwards; • the left border, margo sinister. • the inferior border, margo inferior.
- 4. The sulci of heart The surface of heart features one transverse and two longitudinal sulci that delimit the cardiac chambers from outside. The sulci contain the blood vessels and fat tissue: • the coronary sulcus, sulcus coronarius is a deep circular groove that delimits the atriums and the ventricles. The anterior deeper portion of the groove is covered with the auricles; • the anterior interventricular sulcus, sulcus interventricularis anterior runs along the anterior surface of heart. The sulcus delimits the ventricles anteriorly; • the posterior interventricular sulcus, sulcus interventricularis posterior runs along the inferior surface of heart. It delimits the ventricles posteriorly. The sulci join at the notch of cardiac apex.
- 6. The cardiac chambers The heart features four cham- bers — • two atriums (left and right) and • two ventricles (also left and right). The atriums are separated by the interatrial septum, septum interatriale and the ventricles — by the interventricular septum, septum in- terventriculare. The right atrium and the right ventricle constitute the right (venous) part of heart; the left atrium and the left ventricle constitute the left (arterial) part.
- 7. The right atrium is a cavity of cubic shape with a well distinguishable evagination directed anteromedially — this is the right auricle, auricular dextra that neighbors the aorta on the right. The auricle is delimited from the venae cavae inlet by the sulcus terminalis cordis. The veins that run into the right atrium These veins are both venae cavae and the coronary sinus: • the superior vena cava, opens into the atrium with the opening (ostium) of superior vena cava; the opening is found between the superior and the inferior atrium walls; • the inferior vena cava, opens on the posterior wall with the opening of inferior vena cava; the opening neighbors the sulcus terminalis. A crescent-shaped fold that expands between the lower border of opening and the interatrial septum is the valve of inferior vena cava. The venous openings are delimited by a small tuberculum intervenosum. The area that accepts the venae cavae is called the sinus of venae cavae; • sinus coronarius is the venous collector that drains the cardiac walls. Its opening found in between the atrioventricular orifice and the opening of inferior vena cava is rimmed with a small fold — the valve of coronary sinus. The right atrium, atrium dextrum
- 8. The internal surface of the right atrium has the features as follows: • the fossa ovalis is a central excavation of the interatrial septum (1.5-2 cm wide). The floor of the fossa is made up of thin endocardial duplication. The fossa is rimmed with the limbus fossae ovalis. In embryo, the area features the wide opening — the foramen ovale, that communicates the atriums. Shortly after delivery the foramen closes; • the musculi pectinati are the small muscles situated next to right auricle and the right wall of atrium. The rest of the internal surface of right atrium is smooth.
- 9. The right ventricle features a cavity of irregular pyramidal shape with anterior, inferior and medial walls distinguishable. A cross-sectioned cavity resembles crescent. Superiorly, the ventricular cavity communicates with the right atrium via wide ostium atrioventriculare dexter; anteriorly, the ventricle is continuous with the pulmonary trunk. The tricuspid valve (the right atrioventricular valve), resides within the right atrioventricular orifice. Its name arises from the number of cusps featured. The valve features the anterior, the posterior and the septal cusps (the valve cusps are irregular in number): • the anterior cusp, cuspis anterior resides anteriorly; • the posterior cusp, cuspis posterior resides posteriorly • the septal cusp, cuspis septalis is the smallest medial cusp. The cusps fix firmly to the right fibrous ring that encircles the orifice. The chordae tendineae arise from the papillary muscles and the ventricular walls (the latter are the false chordae tendineae) and attach to free margins of cusps. The right ventricle, ventriculus dexter
- 10. The papillary muscles, are the conic muscular projections on the internal surface of ventricle. The right ventricle features the muscles as follows: • the anterior papillary muscle, the greatest muscle of the group. It attaches to the anterior and the posterior valve cusps (by means of chordae tendineae); • the posterior papillary muscle, musculus papillaris posterior some-what smaller, it attaches to the anterior and the posterior cusps; • the septal papillary muscle, appears as a group of small muscular projections that attach to the septal and the anterior cusps. The internal surface of the ventricle features numerous trabeculae carneae that form the networks. The conus arteriosus is the antero-superior portion of the ventricle with smooth walls. The conus narrows and becomes continuous with the pulmonary trunk. Its opening — the opening of pulmonary trunk, features the valve. The right ventricle, ventriculus dexter
- 11. The pulmonary valve situated within the opening of pulmonary trunk features three cusps; they appear as three small pouches: • valvula semilunaris anterior; • valvula semilunaris sinistra; • valvula semilunaris dextra; The spaces bounded by the cusps and the trunk wall are the sinuses of pulmonary trunk. Each free margin of the cusp features small nodules of semilunar cusp, for better cusp contact.
- 13. The left atrium, atrium sinistrum The space of left atrium is of irregular cubic shape. The anterior wall projection is the auricula sisnistra. The auricle neighbors the pulmonary trunk. The internal surface of auricle features well visible ridges formed of musculi pectinati. The rest of internal surface is smooth. The interatrial septum features the thinner area related to the fossa ovalis.
- 14. The pulmonary veins The left atrium accepts four pulmonary veins (two from each lung) that carry oxygenated blood: • vena pulmonalis superior dextra: • vena pulmonalis inferior dextra; • vena pulmonalis superior sinistra; • vena pulmonalis inferior sinistra; The openings of pulmonary veins, ostia venarum pulmonalium reside on the posterior wall of atrium; the veins lack valves. Sometimes any pair of veins merges to open into the atrium with an unpaired trunk. In this case, the atrium features fewer openings.
- 15. The left ventricle, ventriculus sinister The left ventricle features a cone-shaped cavity. Cross-sectioned cavity is of oval shape. The upper portion of the ventricle features two openings — the ostium atrioventriculare sinistrum and the ostium aortae (found superiorly and to the right from the left atrioventricular orifice). The mitral (left) atrioventricular valve (valva mitralis) occupies the respective opening. Because of two cusps present, the valve sometimes is called the bicuspid valve.The mitral valve features the anterior and the posterior cusps: • the anterior cusp, resides anteriorly and on the right; • the posterior cusp, somewhat smaller, it is found posteriorly and on the left; The cusps fix firmly to the left fibrous ring that encircles the orifice. The chordae tendineae given by the papillary muscles attach to the free margins of cusps.
- 16. The papillary muscles The left ventricle features two greater papillary muscles — the anterior and the posterior: • musculus papillaris anterior resides on the anterior ventricular wall; • musculus papillaris posterior resides on the posterior ventricular wall; The muscles attach to both cusps by means of chordae tendineae. The internal surface of the ventricle features numerous trabeculae carneae that run in all directions and give a reticular look to the inner ventricular surface.
- 17. The left ventricle, ventriculus sinister The aortic valve: The ventricular cavity becomes continuous with the aorta; the aortic orifice, ostium aortae features the aortic valve, valva aortae. The valve comprises three semilunar cusps : • valvula semilunaris posterior (valvula non coronaria); • valvula semilunaris (coronaria) sinistra; • valvula semilunaris (coronaria) dextra. The spaces bounded by the cusps and the aortic wall are the aortic sinuses, sinus aortae. The right and the left sinuses house the openings of the respective coronary arteries. The free margins of cusps feature nodules of semilunar cusp. Laterally from the nodules, one can distinguish thickened areas called the lunulae valvularum semilunarium.
- 18. Clinical applications The heart valves often undergo pathological alterations. The damaged cusps may fuse or become dense and inflexible. The effected valves produce two common states — valve insufficiency and stenosis. Insufficiency constitutes incomplete closing of valve cusps followed by blood regurgitation (backflow). Stenosis (narrowing) stands for failure of valve to open completely, which slows the blood flow. Combined pathologies are also of frequent occurrence. The mitral valve is most frequently affected (two thirds of acquired pathologies); the aortic valve occupies the second place in the list. Nowadays, the pathologies are successfully treated by replacement of the valves affected with the artificial valve prostheses (the xeno - grafted valves are also in use).
- 19. The interventricular septum (IVS), (or ventricular septum, or during development septum inferius), is the stout wall separating the lower chambers (the ventricles) of the heart from one another. The ventricular septum is directed obliquely backward to the right, and curved with the convexity toward the right ventricle; its margins correspond with the anterior and posterior longitudinal sulci. Portions: • The greater portion of it is thick and muscular and constitutes the muscular interventricular septum. • Its upper and posterior part, which separates the aortic vestibule from the lower part of the right atrium and upper part of the right ventricle, is thin and fibrous, and is termed the membranous ventricular septum (septum membranaceum).. The interventricular septum
- 20. The wall layers The cardiac wall consists of three layers — the epicardium, the myocardium and the endocardium: • the epicardium is the external layer represented with visceral plate of cardiac serous coating (the pericardium), immediately below it, one can see fat tissue best developed in the sulci; • the myocardium is the thickest middle layer of heart. The myocardium contains specific muscular bundles of the conductive system of heart; • the endocardium is the internal investment of cardiac chambers. The valves are the endocardial duplications with dense fibrous tissue featured. . WALL STRUCTURE OF HEART
- 21. The fibrous rings, anuli fibrosi The muscular fibers and the valves attach to the fibrous rings that constitute a dense fibrous skeleton of heart. The heart features four fibrous rings: 1) anulus fibrosus sinister rims the left atrioventricular orifice; 2) anulus fibrosus dexter rims the right atrioventricular orifice; 3) the fibrous ring around the opening of pulmonary trunk; 4) the fibrous ring around the aortic opening. The left fibrous ring fuses with the aortic ring to give rise to two left and right trigonum fibrosum dexter et sinister situated posterior to the aorta. The rings and the trigones separate the atrial myocardium from the ventricular
- 22. WALL STRUCTURE OF HEART The atrial myocardium is a thinner (2-3 mm) muscular layer. It arises from the fibrous rings and features two layers — •the superficial and •the deep. The superficial layer shared by atriums features transverse muscular fibers. In the deep layer, the fibers are longitudinal and circular. The longitudinal fibers prevail; they enfold each atrium separately and form sphincters around venous openings. The longitudinal fibers give rise to muscili pectinati. The ventricular myocardium is thicker than that of atriums. The left ventricle has the thickest muscular layer — about 1.5 cm. The right ventricle wall is somewhat thinner — about 0.7-0.8 cm.
- 23. The ventricular myocardium comprises complex system of interlaced and looping fibers arranged in three layers: •the external (oblique) layer arises from anterior portion of each fibrous ring; it runs slantwise inferiorly and leftwards to reach the apex. On reaching the apex, the fibers loop to form the vortex of heart, vortex cordis and become continuous with the •internal longitudinal layer. The longitudinal layer gives rise to the trabeculae carneae and the papillary muscles. Both layers are shared by the ventricles; •the middle layer comprises transverse fibers that enfold each ventricle separately. This layer is the strongest one. Nowadays, the cardiac muscular fibers are believed to form the three dimensional network. Continuous changing of fibers direction provides more efficient force application.
- 25. THE CONDUCTING SYSTEM OF HEART The conducting system of heart comprises specific muscular fibers (light, poor in myofilaments and reach in sarcoplasm) with featured automation i.e. with possibility of generation and transmission of rhythmic impulses to the working myocardium. The system ensures successive contractions (systole) of the atriums and the ventricles. The conducting system features nodes and bundles (the latter conduct the impulses) . • The sinu-atrial node, (node of Keith-Flack) resides within the right atrial wall immediately below the epicardium between the superior vena cava and the right auricle. The node sizes 2X2 mm. the node accepts numerous nerve fibers. The node generates impulses at rate of 60-80 bpm (resting rate); the impulses expand along the bundles to reach the atrial myocardium and the atrioventricular node. The node is the principal pacemaker (all components of conductive system have pacemaking properties).
- 26. The atrioventricular node, (node of Aschoff- Tawara) resides right below the endocardium within the upper portion of the interventricular septum on the right. It sizes 5 X 3 mm. The atrioventricular node is associated with the sinu- atrial node. The atrioventricular node gives rise to the atrioventricular bundle.
- 27. THE CONDUCTING SYSTEM OF HEART The atrioventricular bundle, fasciculus atrioventricularis (the bundle of His) arises from the atrioventricular node, traverses the right fibrous triangle and becomes evident within the interventricular septum as 1 cm long trunk. Within the interventricular septum, the bundle splits into the left and the right bundles, crus dextrum et crus sinistrum. The crura descend below the endocardium on each side of the interventricular septum. The crura split into numerous subendocardial branches, rami subendocardiales (the fibers of Purkinje) that penetrate the trabeculae carneae, the papillary muscles and working myocardium. The atrioventricular bundle conducts the impulses from the atriums to the ventricular myocardium.
- 28. Clinical applications Impulses generated by the conducting system of heart can easily be registered by means of ECG. As far as many cardiac diseases are complicated with conductivity disorders, ECG is a very important diagnostic procedure. Myocardial infarction of the interventricular septum (where the atrioventricular bundle passes) is quite dangerous because it causes conductivity block.