heart intro.pptx full introduction about the heart

Anatomy of heart thus includes the superior vena cava and inferior vena cava the aorta etc..

1. HEART Dr. SNEHA Assistant professor Department of anatomy

2. Heart Is a hollow muscular organ situated in the mediastinum of the thoracic cavity, enclosed in the pericardium. It is somewhat pyramidal in shape and placed obliquely behind the sternum and adjoining parts of costal cartilages so that one-third of the heart is to the right of median plane and two-third of the heart is to the left of median plane.

3. Heart consists of four chambers- Right atrium and Right ventricle, and left atrium and left ventricle. On the surface the atria are separated from the ventricles by the atrioventricular groove and ventricles each other by interventricular grooves.

4. Shape and Measurements Shape : Pyramidal or conical Length : 12 cm Width : 9cm Weight : 300 g in males, 250 g in females

5. EXTERNAL FEATURES APEX BASE THREE SURFACES (STERNOCOSTAL, DIAPHRAGMATIC, AND LEFT) FOUR BORDERS (RIGHT, LEFT, UPPER AND INFERIOR)

6. APEX

7. APEX OF THE HEART Is a conical area formed by the left ventricle. It is directed downwards and forwards, and to the left. It lies at the level of 5 th intercostal space, 3.5 inches (9cm) from the midline and just medial to the midclavicular line.

8. BASE OF HEART

9. BASE OF HEART The base or (Posterior surface) of the heart is formed by two atria, mainly by left atria. Two-thirds of the base is formed by the posterior surface of the left atrium and one –third by the posterior surface of the right atrium. It is directed to backwards into the right (opposite to apex)

10. BASE- CHARACTERISTIC FEATURES It lies opposite to the apex. It lies in front of the middle four thoracic vertebra ( i.e , T5-T8) in the lying down position and descends one vertebra in the erect posture (T6-T9) Base is separated from vertebral column by the oblique pericardial sinus, esophagus and aorta. Clinically base is upper border of the heart where great blood vessels (superior vena cava, ascending aorta and pulmonary trunk are attached.

11. SURFACES OF HEART Heart has three surfaces Sternocostal (anterior ) Diaphragmatic (inferior) Left surface.

12. Sternocostal Surface It is formed mainly by the Right Atrium and Right ventricle, which are separated from each other by the anterior part of AV groove. Sternocostal surface is also partly formed by the left auricle and left ventricle. The right ventricle is separated from the left ventricle by the anterior interventricular groove.

13. DIAPHRAGMATIC SURFACE This surface is flat and rests on the central tendon of the diaphragm. It is formed by the left and right ventricles which are separated from each other by the posterior interventricular groove. The left ventricles form left two-third of this surface and right ventricle forms only right one-third on this surface.

14. LEFT SURFACE It is formed mainly by the left ventricle and partly by the left atrium and auricle. It is directed upwards, backwards and to the left.

15. BORDERS OF HEART

16. UPPER BORDER Upper border is slightly oblique, and formed by the two atria, chiefly the left atrium.

17. RIGHT BORDER OF HEART More or less vertical and is formed by the Right atrium. It extends from Superior vena cava to Inferior vena cava.

18. INFERIOR BORDER Inferior border is nearly horizontal and is formed mainly by the right ventricle. A small part of it near the apex is formed by the left ventricle. It extends from Inferior vena cava to apex.

19. LEFT BORDER Left border is oblique and curved. It is formed mainly by the left ventricle, and partly by the left auricle. It separates the anterior and left surfaces of heart. It extends from apex to left auricle.

20. CHAMBERS OF HEART RIGHT ATRIUM Right atrium is the right upper chamber of heart. Receives venous blood from the whole body, pumps it to the right ventricle through right atrioventricular or tricuspid opening. It forms the right border, part of the upper border, the sternocostal surface and the base of heart.

21. EXTERNAL FEATURES Chamber is elongated vertically, receiving superior vena cava at the upper end and the inferior vena cava at the lower end. The upper end is prolonged to the left to form the right auricle. The auricle covers the root of ascending aorta and partly overlaps the infundibulum of right ventricle. Its margins are notched and the interior is sponge like, which prevents free flow of blood .

22. Along the right border of atrium, there is a shallow vertical groove which passes from the superior vena cava. This groove is called as Sulcus Terminalis .

23. It is produced by an internal muscular ridge called CRISTA TERMINALIS The upper part of the sulcus contains the sinuatrial or SA node which acts as the pacemaker of the heart. The right atrioventricular groove separates the right atrium from the right ventricle. It is more or less vertical and lodges the right coronary artery and the small cardiac vein.

24. TRIBUTARIES/INLETS OF THE RIGHT ATRIUM

25. Superior vena cava Inferior vena cava Coronary sinus Anterior cardiac veins Venae cordis minimae ( thebesian veins) Sometimes the right marginal vein

26. RIGHT ATRIOVENTRICULAR ORIFICE

27. Blood passes out of the right atrium through the right atrioventricular or tricuspid orifice and goes to the right ventricle. The tricuspid orifice is guarded by the tricuspid valve which maintains unidirectional flow of blood.

28. INTERNAL FEATURES Interior of right atrium can be divided into Smooth posterior part or sinus venarum Rough anterior part or Pectinate part, including the auricle Interatrial septum

29. Smooth posterior part/sinus venarum Developmentally it is derived from the right horn of the sinus venosus . Most of the tributaries except the cardiac veins open into Superior vena cava opens at the upper end. Inferior vena cava opens at the lower end. The opening of the inferior vena cava is guarded by a rudimentary valve of the inferior vena cava or eustachian valve.

30. Coronary sinus opens between the opening of Inferior vena cava and right atrioventricular orifice. The opening is guarded by valve of coronary sinus or thebesian valve. Venae cordis minimae are numerous and small veins present In the walls of all four chambers. They open into right atrium through small foramina.

31. ROUGH ANTERIOR PART/PECTINATE PART INCLUDING AURICLE Developmentally it is derived from the primitive atrial chamber. It presents a series of transverse muscular ridges called Musculi pectinati . They arise from the crista terminalis and runs forwards and downwards towards the right atrioventricular orifice, giving the appearance of the teeth of comb. In the auricle the muscles are interconnected to form a reticular network.

32. Interatrial septum Developmentally it is derived from the septum primum and septum secondum . It presents the fossa ovalis , a shallow saucer shaped depression in the lower part. The fossa represents the site of the embryonic septum primum . Tha annulus ovalis or limbus (border) fossa ovalis is prominent margin of fossa ovalis . It represents the lower free edge of the septum secundum . It is distinct above and at the sides of the fossa ovalis , deficient inferiorly.

33. Its anterior edge is continuous with the left end of the valve of inferior vena cava. The remains of the foramen ovale are occasionally present. This is a small slit like valvular opening between the upper part of the fossa and limbus . It normally occluded after birth, but may sometimes persists.

34. The intervenous tubercle of lower is a very small projection, scarcely visible on the posterior wall of the atrium just below the opening of superior vena cava.

35. RIGHT VENTRICLE

36. Position Right ventricle is a triangular chamber receives blood from right atrium and pumps it into lungs through pulmonary trunk and pulmonary arteries. It forms the inferior border and two-thirds part of the sternocostal surface and one-third part of inferior surface of the heart.

37. EXTERNAL FEATURES Externally the Right ventricle has two surfaces Anterior/ sternocostal surface and Inferior or diaphragmatic. Interior two parts Inflowing part – is rough due to the presence of muscular ridges called trabeculae carneae it develops from the proximal part of the bulbus cordis of the heart tube.

38. The outflowing part or infundibulum is smooth and forms the upper conical part of the right ventricle which gives rise to the pulmonary trunk. It develops from the midportion of bulbus cordis . The two parts are separated by a muscular ridge called the supraventricular crest or infundibuloventricular crest situated between the tricuspid and pulmonary orifices.

39. INTERNAL FEATURES Interior shows two orifices The right atrioventricular or tricuspid orifice, guarded by the tricuspid valve The pulmonary orifice guarded by the pulmonary valve

40. The interior or inflowing part shows Trabeculae carneae or muscular ridges of three types. Ridges or fixed elevations Bridges Pillars or papillary muscles with one end attached to the ventricular wall, and the other end connected to the cusps of the tricuspid valve by chordae tendinae .

41. There are three papillary muscles in the right ventricle- anterior,posterior and septal . The anterior muscle is the largest. The posterior or inferior muscle is small and irregular. The septal muscle is divided into number of little nipples. Each papillary muscle is attached by chordae tendinae to the contiguous sides of cusps.

42. The septomarginal trabecula or moderator band is a muscular ridge extending from the ventricular septum to the base of the anterior papillary muscle. It contains the right branch of the AV bundle.

43. The cavity of the right ventricle is crescentic in section because of the forward bulge of the interventricular septum. The wall of the right ventricle is thinner than that of the left ventricle in ratio of 1:3

44. INTERVENTRICULAR SEPTUM

45. The septum is placed obliquely. Its one surface faces forwards and to the right and the other faces backwards and to the left. The upper part of the septum is thin and membranous and separates not only the two ventricles but also the right atrium and left ventricle The lower part is thick muscular and separates the two ventricles. Its position is indicated by the anterior and posterior interventricular grooves.

46. LEFT ATRIUM

47. Left atrium is quadrangular chamber situated posteriorly. Its appendage the left auricle projects anteriorly to overlap the infundibulum of the right ventricle. The left atrium forms the left two-thirds of the base of the heart, the greater part of the upper border, parts of the sternocostal and left surfaces and left border.

48. LA receives oxygenated blood from the lungs through pulmonary veins and pumps it into left ventricle through left atrioventricular or bicuspid or mitral orifice which is guarded by valve of the same name.

49. FEATURES Posterior surface of the atrium forms the anterior wall of the oblique sinus of the pericardium The anterior wall of the atrium is formed by the interatrial septum. Two pulmonary veins open into the atrium on each side of the posterior wall.

50. The greater part of the interior of the atrium is smooth walled. It is derived embryogically from the absorbed pulmonary veins which open into it. Musculi pectinati are present only in auricle where they form reticulum. This part develops from the original primitive atrial chamber of the heart tube.

51. LEFT VENTRICLE

52. The left ventricle receives oxygenated blood from the left atrium and pumps it into aorta. It forms the apex of the heart, a part of sternocostal surface and the left two-thirds of the diaphragmatic surface.

53. FEATURES Externally the left ventricle has three surfaces- anterior or sternocostal , inferior or diaphragmatic and the left. The interior is divisible into two parts. The lower rough part with trabeculae carneae develops from the primitive ventricle of the heart tube.

54. The upper smooth part of the aortic vestibule gives origin to the ascending aorta: it develops from the midportion of the bulbus cordis . The vestibule lies between the membranous part of the interventricular septum and anterior or aortic cusp of the mitral valve.

55. The interior of the ventricle shows two orifices: The left atriventricular or bicuspid or mitral orifice, guarded by the bicuspid or mitral valve. The aortic orifice, guarded by the aortic valve. There are two well developed papillary muscles-anterior and posterior. Chordae tendinae from both muscles attached to the cusps of mitral valve. The cavity of the left ventricle is circular in cross section.

56. The walls of the left ventricle are three times thicker than those of the right ventricle.

57. STRUCTURE OF HEART VALVES Valves of the heart maintains unidirectional flow of the blood and prevent its regurgitation in the opposite direction. There are two pairs of valves in the heart A pair of Atrioventricular valves and a pair of semilunar valves The right atrioventricular valve is known as the Tricuspid valve because it has three cusps.

58. The left atrioventricular valves is known as bicuspid valve because it has two cusps. It is also called the mitral valve. The semilunar valves include the aortic and pulmonary valves, each having three semilunar cusps.

59. ATRIOVENTRICULAR VALVES Both valves are made up of Fibrous ring to which cusps are attached Cusps are flat and project into the ventricular cavity. Each cusp has an attached and a free margin, and an atrial and ventricular surface. Atrial surface is smooth. The free margins and ventricular surfaces are rough and irregular due to the attachment of chordae tendinae .

60. Chordae tendinae connect the free margins and ventricular surfaces of the apices of the papillary muscles Prevent erosion of the free margins and limit amount of ballooning of the cusps towards the cavity of the atrium. The AV valves are kept competent by active contraction of the papillary muscles, which pull on the chordae tendinae during ventricular systole.

61. Blood vessels are present only in the fibrous ring and the basal one-third of the cusps. Nutrition to the central two-thirds of the cusps is derived directly from the blood in the cavity of the chest. The tricuspid valve has three cusps and can admit the tips of three fingers. The three cusps- the anterior, posterior/inferior and septal .

62. These lie against the walls of the ventricle. Of the three papillary muscles the anterior is the largest, the inferior is the small and irregular and the septal is represented by number of small muscular elevations. The mitral or bicuspid valve has two cusps- a large anterior or aortic cusp and a small posterior cusp. It admits the tips of two fingers. The anterior cusp lies between the mitral and aortic orifices

63. The mitral cusps are smaller and thicker than those of the tricuspid valve.

64. SEMILUNAR VALVES Aortic and pulmonary valves are called semilunar valves because their cusps are semilunar in shape. Both valves are similar to each other. Each valve has three cusps which are attached directly to the vessel wall, there being no fibrous ring. The cusps form small pockets with their mouths directed away from the ventricular cavity. the free margin of each cusp contains a central fibrous nodule from each side of which a thin smooth margin the lunule extends up to the base of the cusp.

65. These valves are closed during ventricular diastole when each cusp bulges towards ventricular cavity. Opposite the cusps, the vessel walls are slightly dilated to form the aortic and pulmonary sinuses. The coronary arteries arise from the anterior and left posterior aortic sinuses.

66. FIBROUS SKELETON The fibrous ring surrounding the atrioventricular and arterial orifices, along the adjoining masses of the fibrous tissue constitute the fibrous skeleton of the heart. It provides attachment to the cardiac muscle and keeps the cardiac valves competent.

67. There is a large mass of fibrous tissue between the atrioventricular rings behind the aortic ring in front. It is known as the Trigonum fibrosum dextrum . Another small mass of fibrous tissue is present between the aortic and mitral rings. It is known as the Trigonum fibrosum sinistrum . The tendon of the infundibulum (close to pulmonary valve) binds to the posterior surface of the infundibulum to the aortic ring.