ANATOMY OF HEART - CARDIOVASCULAR SYSTEM

Anatomy of heart

1. Anatomy of heart

2. POSITION OF HEART It is placed obliquely behind the body of sternum. Heart is conical hollow muscular organ situated in the middle of mediastinum

3. STRUCTURE OF HEART It is enclosed in a fibrous sac called pericardium. Which consists of fibrous pericardium and serous pericardium.

4. EXTERNAL FEATURES OF HEART Apex: formed entirely by left ventricle. Directed downwards,forwards,and to the left. It is situated in the left fifth intercostal space 9 cm lateral to the midsternal line.

5. BASE OF THE HEART Also called posterior surface of the heart. Formed mainly by the left atrium and small part of right atrium. In relation to the base we can see the opening of 4 pulmonary veins which opens into left atrium and superior and inferior vena cava which opens into right atrium.

6. BORDERS OF HEART Upper border is slightly oblique and is formed by 2 atria mainly by the left atrium. Right border is more or less verticle and is formed by the right atrium. It extends from SVC to IVC. Inferior border is nearly horizontal and formed mainly by the right ventricle. A small part of it is formed by apex. Left border is oblique and curved and formed by the left ventricle and by the left auricle.

7. Cardiac shadow in chest X-Ray

8. Surfaces of heart Anterior or sternocostal surface is formed mainly by the right atrium and right ventricle. Inferior or diaphragmatic surface rests on the central tendon of diaphragm. And is formed left two third by left ventricle and right one third by right ventricle. The left surface is formed mainly by the left ventricle and partly by the left auricle.

9. TYPES OF CIRCULATIONS Systemic and Pulmonary

10. Right Atrium Right upper chamber of the heart. Receives venous blood from the whole body and pumps to the right ventricle. It is elongated vertically receiving SVC from the upper end and IVC from the lower end. Along the right border there is a shallow vertical groove which passes from SVC to IVC and this groove is called Sulcus Terminalis and produced by the internal muscular ridge called crista terminalis.

11. INTERNAL FEATURES OF RIGHT ATRIUM Smooth or posterior part: most tributaries like SVC and IVC opens into it. Rough or anterior part: presents series of transverse muscular ridges called musculi pectinati It receives coronary sinus at the smooth end.

12. Right Ventricle Triangular chamber which receives blood from right atrium and pumps it into the lungs via pulmonary veins. It has two surfaces anterior or sternocostal and inferior or diaphragmatic. Internally it has two orifices : tricuspid orifice guarded by tricuspid valve and pulmonary orifice guarded by pulmonary valve. The wall of right ventricle is thinner than that of left ventricle.

13. Tricuspid valve Controls the flow from right atrium to right ventricle. These are muscular ridges which extends from ventricular septum to the base of the anterior papillary muscle.

14. Left atrium Quadrangular chamber situated posteriorly. It forms the left two third of the base of the heart, greater part of the upper border and parts of sternocostal border. It receives oxygenated blood from lungs via pulmonary veins

15. Left ventricle Receives oxygenated blood from left atrium and pumps to the whole body via Aorta. Externally it is divided into three surfaces anterior or sternocostal, inferior or diaphragmatic and left surface. Internally it has two parts Lower rough part with trabeculae carnae. Upper smooth part or aortic vestibule which gives origin to ascending aorta. It has two orifices bicuspid or mitral orifice guarded by mitral valve and aortic orifice guarded by aortic valve. The walls of left ventricles are three times thicker than that of right ventricle.

16. AORTA Largest artery of the body carries blood from to the whole body. It originates from left ventricle. Branches of arch of aorta Brachiocephalic trunk Left common carotid artery Subclavian artery

17. Mitral/bicuspid valve It has 2 cusps A large anterior and aortic cusp which lies between mitral and aortic orifices A small posterior or mitral cusp. It is smaller and thicker than tricuspid valve.

18. SEMILUNAR VALVES AORTIC VALVE It is located in left ventricle of the heart. It has three cusps which when closed they contain a sinus called aortic sinus or sinus of Valsalva. Aortic valves is open ventricular systole. Pulmonary valve This valve is located between right ventricle. Also has three cusps. Similar to aortic valve this valve opens in ventricular systole.

19. ARTERIAL SUPPLY OF HEART

20. Branches of right coronary artery Atrial branches are anterior posterior and lateral. One of the posterior branches is called SA nodal artery. Right conus forms an arterial circle around pulmonary trunk with a similar branch from the left coronary artery. Ventricular branches are as anterior and posterior group. Anterior group lies on the sternocostal surface while posterior group transverse the diaphragmatic surface of heart. Right marginal artery arises as right coronary artery crosses the right border of heart.

21. LEFT CORNARY ARTERY Left coronary artery is larger than right coronary artery and arises from left posterior aortic sinus of ascending aorta. Course: It first runs forwards and to the left and emerges between the pulmonary trunk and the left auricle. Here it gives anterior interventricular branch which runs downward into the groove. After giving off the anterior interventricular branch it runs to the left in the left anterior coronary sulcus. It winds around the left border of the heart and continues in the posterior coronary sulcus and terminates with anastomosing with the right coronary artery.

22. Branches of left coronary artery Anterior interventricular branch is the largest branch, it descends in the interventricular groove and gives following branches: 1. Anterior ventricular branches for the ventricles. The large branch is called left diagonal artery. 2. Septal branch supply anterior two third of the interventricular septum, 3. Left conus artery forms an arterial ring around the pulmonary trunk with similar branch from right coronary artery. Circumflex branch is the terminal branch of left coronary artery and gives following branches: 1. Left marginal artery which lies along the left border of the heart till the apex. Anterior and posterior ventricular branches. Arterial branches which are in anterior posterior and lateral groups.

23. Veins of the heart Great cardiac vein Middle cardiac vein Right marginal vein Posterior vein of the left ventricle Oblique vein of the left atrium Anterior cardiac veins Venae cordis minimae

24. NERVE SUPPLY OF HEART Heart is supplied by both sympathetic and parasympathetic fibres. Parasympathetic nerve reach the heart via vagus nerve. Sympathetic nerves are derived from upper four to five thoracic segments of the spinal cord. Both parasympathetic and sympathetic nerves form the superficial and deep cardiac plexus, the branches of which run along the coronary arteries to reach the myocardium.

25. Apical view of heart in ECHO.

26. Parasternal view of heart in Echocardiogram

27. How heart look in ECHO?