The heart itself recieves its blood supply through the coronary circulation. It is the shortest circulation in the body
The arterial supply of coronary circulation is provided by Right and Left coronary arteries, which arise from the base of ascending aorta (from the anterior and posterior aortic sinuses) and encircle the heart in the atrioventricular groove like a crown. These vessels supply the entire cardiac musculature via their branches.
Left coronary artery is larger in diameter than the right coronary artery and arises from the posterior aortic sinus of ascending aorta. It passes posterior to the pulmonary trunk, then divides into two branches; the anterior interventricular / left anterior descending artery and the circumflex artery.
The anterior interventricular artery descends into the anterior interventricular groove towards the apex of the heart. It supplies the interventricular septum as well as the anterior walls of both ventricles. The circumflex artery follows the coronary (atrioventricular) sulcus posteriorly and supplies the left atrium and the posterior part of the left ventricle.
The right coronary artery emerges from the anterior aortic sinus and descends in the coronary sulcus on the anterior surface of the heart, between the right atrium and right ventricle. At the inferior border of the heart, the artery branches to give off the right marginal artery. Continuing into the posterior part of the coronary sulcus, the right coronary artery branches to give off the posterior interventricular artery that runs in the posterior interventricular groove. Overall, the branches of the right coronary artery supply the right atrium and almost all of the right ventricle.
The arrangement of the coronary arteries varies considerably in every individual. For example, in about 15% of people, the left coronary artery gives rise to both (anterior and posterior) interventricular arteries. In a small number of people (4%), one single coronary artery arises from ascending aorta and supplies the entire heart.
The venous blood is collected by the cardiac veins that roughly follow the path of coronary arteries. All the cardiac veins ultimately join to form an enlarged vessel known as the Coronary sinus which occupies the posterior part of the coronary sulcus. The sinus opens into the right atrium between the opening of the inferior vena cava and the tricuspid valve. The opening of the sinus is guarded by an endothelial fold (semilunar valve of the coronary sinus). The coronary sinus returns almost all the venous blood from the heart into the right atrium.
Tributaries of coronary sinus are as follows:
The Great cardiac vein, which begins at the cardiac apex and runs in the anterior interventricular sulcus along with anterior interventricular artery, drains the areas of the heart supplied by the left coronary artery, i.e. left and right ventricles and left atrium.
The Middle cardiac vein, which accompanies the posterior interventricular artery in the posterior interventricular sulcus, drains the areas supplied by the posterior interventricular branch of right coronary artery.
The Small cardiac vein, which runs in the posterior atrioventricular (AV) groove and opens into the coronary sinus near its atrial end, drains blood from the posterior part of the right atrium and ventricle.
The Oblique vein of the left atrium descends obliquely on the back of the left atrium to join the coronary sinus near its end.
Other Cardiac Veins Draining Independently into the Right Atrium
Two additional groups of cardiac veins are also involved in the venous drainage of the heart.
The anterior veins of right ventricle (anterior cardiac veins) are small veins that arise on the anterior surface of the right ventricle. They cross the coronary sulcus and enter the anterior wall of the right atrium. They drain the anterior portion of the right ventricle.
Venae cordis minimae, or veins of Thebesius, are a group of smallest cardiac veins. These drain directly into the chambers of the heart and are numerous in the right atrium and right ventricle. Can you think why they might be more numerous on the right side of the heart than the left?
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