Heart Artery|Coronary Artery.
Like all other body parts, the heart also requires blood supply for oxygen and nutrients to function. Though it is filled with blood, the myocardium receives its blood supply from its own network of arteries. The heart artery called the coronary artery supplies oxygen rich blood to the heart muscle through its network of heart arteries. The blood vessels of the heart that remove deoxygenated blood from the cardiac muscle are called cardiac veins.
Blood Vessels of Heart|Coronary Circulation.
The blood vessels of the heart, supplying blood to the heart muscle constitute the coronary circulation or the heart circulation. The coronary circulation is one of the three circulatory systems of the body, the other two being the systemic circulation (of the body) and the pulmonary circulation (of the lungs).
The coronary circulation or the blood vessels of the heart consists of the
- The coronary arteries which supply oxygen rich blood to the heart muscle (myocardium) and the septum of the heart, and
- The cardiac veins or the coronary veins which remove deoxygenated blood from the heart muscle.
Coronary Arteries.
The coronary arteries or heart arteries which run on the surface of the heart wall are called epicardial coronary arteries. They are commonly affected by atherosclerosis (fat deposits of plaques on their inner wall) and since they are relatively narrow, they tend to get blocked easily which leads to angina or heart attack. The arteries of the heart which run deep in the myocardium are called subendocardial arteries.
Two major coronary arteries arise from the aorta just after its origin from the left ventricle above the aortic valve. They are the
Right Coronary Artery which arises from the right aortic sinus, supplies oxygenated blood to the wall of the right atrium and the right ventricle.
- It then branches into the posterior descending artery which supplies the inferior portion of the wall of the left ventricle and the back portion of the septum.
Left Main Coronary Artery arises from the left aortic sinus produces two branches:
- The Circumflex artery supplies oxygenated blood to the wall of the left atrium and the side and back portion of the wall of the left ventricle.
- The left anterior descending artery supplies the front and bottom portion of the wall of the left ventricle and the front portion of the septum.
Image showing arteries of the heart.
The coronary network also has collateral arteries which are normally not open. When and if some coronary arteries become narrow due to coronary artery disease and blood supply to a portion of the heart wall is hampered, a network of tiny arteries which comprise the collateral vessels get enlarged and open to allow blood flow around the blocked artery to the affected part of the heart muscle.
Blood Supply of the Papillary Muscles.
The Papillary muscles anchor the atrioventricular valves ( the mitral and tricuspid valves) to the walls of the ventricles. Improper functioning of these muscles can lead to regurgitation or incompetence of these valves. These papillary muscles are supplied blood by the posterior descending artery, the circumflex artery and the left anterior artery.
Coronary Blood Flow.
Most myocardial perfusion occurs during diastole (relaxation of the heart muscle) because during systole (contraction of the heart) the heart muscle contracts with pressure causing compression of the subendocardial arteries in the myocardium. As a result blood flow in the subendocardium stops.
However the epicardial coronary arteries which lie on the surface of the heart remain patent. Myocardial blood supply therefore mostly occurs during diastole when the subendocardial coronary arteries are open and not compressed.
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