The heart is supplied exclusively by the right and left coronary arteries. The coronary arteries are functional end arteries. There is no effective anastamosis between right and left coronary arteries. Therefore, in the event of sudden block of one artery the area of myocardium supplied by that artery undergoes infarction.
Right Coronary Artery
Right coronary artery arises from the anterior aortic sinus. It runs down along the anterior part of the coronary sulcus, reaches the lower border of heart turns round the lower border and lies in the posterior part of the atrioventricular groove. It ends by anastomosing with the circumflex branch of the left coronary artery. Just before its termination it gives off the posterior interventricular branch that runs downwards, forwards and to the left in the posterior interventricular groove. The branches of the right coronary artery are, branches to SA node, branches to right atrium and right ventricle, right marginal artery, posterior interventricular branches and branches to AV node. It is to be noted that the right coronary artery supplies the right atrium, right ventricle and conducting system of the heart.
Left Coronary Artery
The left coronary artery arises from the left posterior aortic sinus. It runs to the left behind the pulmonary trunk and appears between left auricle and pulmonary trunk. In that position the artery divides into anterior interventricular branch and circumflex artery.
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| Arteral supply of the heart |
Circumflex artery turns round the left border of the heart runs through the coronary sulcus between left atrium and left ventricle on the posterior surface of the heart in the posterior part of the atrioventricular groove. It ends by anastomosing with the terminal part of the right coronary artery. The left coronary artery is larger in size than the right coronary artery. The average diameter of left coronary artery is 4 mm. The left coronary artery supplies left ventricle, left atrium, anterior two third of the IV septum and adjacent part of the right ventricle.
The branches of the left coronary artery are anterio interventricular artery (AIV artery) and circumflex artery which is considered to be the continuation of the left coronary artery. It gives rise to the left marginal artery and also few branches for the supply of the posterior surface of the left atrium and left ventricle. Anterior interventricular branch of the left coronary artery supplies the left anterior surface of the left ventricle including the apex, adjoining part of the left ventricle and anterior two-third of the IV septum. The anterior interventricular artery runs along the anterior interventricular sulcus, turns around the inferior border of the heart and anastamoses with the posterior interventricular branch of the right coronary artery. The AIV artery sends a few branches to the anterior surface of the left ventricle. The largest among these is called the diagonal artery. All these arteries arise at an acute angle so that they can are most susceptible to blockage by emboli.
Venous Drainage of the Heart
The coronary sinus is the main vein of the heart and is about 3 cm. long. It lies in the coronary sulcus at the posterior surface of the heart in the posterior atrio-ventricular groove. The coronary sinus opens into the right atrium. Its tributaries are the great cardiac vein, the middle cardiac vein, the small cardiac vein, the posterior vein of the left ventricle and the oblique vein of the left atrium. In addition to the above some anterior cardiac veins lying on the left ventricle open into the right atrium. A number of venae cordis minimae drain directly into the chambers of the heart.
The coronary sinus is the main vein of the heart and is about 3 cm. long. It lies in the coronary sulcus at the posterior surface of the heart in the posterior atrio-ventricular groove. The coronary sinus opens into the right atrium. Its tributaries are the great cardiac vein, the middle cardiac vein, the small cardiac vein, the posterior vein of the left ventricle and the oblique vein of the left atrium. In addition to the above some anterior cardiac veins lying on the left ventricle open into the right atrium. A number of venae cordis minimae drain directly into the chambers of the heart.
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| Venous drainage of the heart |
Pericardium
The heart is enclosed in a membranous sac called the pericardium. It has two layers- the fibrous pericardium which is the outer layer and the serous pericardium that lies inside the fibrous pericardium. The serous pericardium has two layers – the outer parietal and the inner visceral layer. The parietal layer lines the fibrous pericardium and the visceral layer the surfaces of the heart. This visceral layer is also called the epicardium.
The pericardium is conical in shape, the base being directed downwards and is partly fused with the tendon of the diaphragm. The apex is the upper end and is fused with the great blood vessels.
The Lymphatic Drainage of the Heart
The heart is drained by vessels that travel in the interventricular and atrioventricular grooves. One set runs in the anterior part of the atrio-ventricular groove. The vessels of this set cross the aorta and reach the brachio-cephalic nodes. Another set of vessels runs along the anterior interventricular groove and ends in the inferio tracheo-bronchial nodes.
The heart is enclosed in a membranous sac called the pericardium. It has two layers- the fibrous pericardium which is the outer layer and the serous pericardium that lies inside the fibrous pericardium. The serous pericardium has two layers – the outer parietal and the inner visceral layer. The parietal layer lines the fibrous pericardium and the visceral layer the surfaces of the heart. This visceral layer is also called the epicardium.
The pericardium is conical in shape, the base being directed downwards and is partly fused with the tendon of the diaphragm. The apex is the upper end and is fused with the great blood vessels.
The Lymphatic Drainage of the Heart
The heart is drained by vessels that travel in the interventricular and atrioventricular grooves. One set runs in the anterior part of the atrio-ventricular groove. The vessels of this set cross the aorta and reach the brachio-cephalic nodes. Another set of vessels runs along the anterior interventricular groove and ends in the inferio tracheo-bronchial nodes.
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