Coronary arteries

The coronary arteries are mainly composed of the left and right coronary arteries, both of which give off several branches, as shown in the 'coronary artery flow' figure. • Aorta • Left coronary artery • Left anterior descending artery • Left circumflex artery • Posterior descending artery • Ramus or intermediate artery • Right coronary artery • Right marginal artery • Posterior descending artery The left coronary artery arises from the aorta within the left cusp of the aortic valve and feeds blood to the left side of the heart. It branches into two arteries, the left anterior descending and the left circumflex. The left anterior descending artery perfuses the interventricular septum and anterior wall of the left ventricle. The left circumflex artery perfuses the left ventricular free wall. In approximately 33% of individuals, the left coronary artery gives rise to the posterior descending artery which perfuses the posterior and inferior walls of the left ventricle. Sometimes a third branch is formed at the fork between left anterior descending and left circumflex arteries, known as a ramus or intermediate artery. The right coronary artery (RCA) originates within the right cusp of the aortic valve. It travels down the right coronary sulcus, towards the crux of the heart. The RCA primarily branches into the right marginal arteries, and, in 67% of individuals, gives place to the posterior descending artery. ==Clinical significance==

Narrowing of the arteries can be caused by a process known as atherosclerosis (most common), arteriosclerosis, or arteriolosclerosis. This occurs when plaques (made up of deposits of cholesterol and other substances) build up over time in the walls of the arteries. Coronary artery disease (CAD) or ischemic heart disease are the terms used to describe narrowing of the coronary arteries. As the disease progresses, plaque buildup can partially block blood flow to the heart muscle. Without enough blood supply (ischemia), the heart is unable to work properly, especially under increased stress. Stable angina is chest pain on exertion that improves with rest. Unstable angina is chest pain that can occur at rest, feels more severe, and/or last longer than stable angina. It is caused by more severe narrowing of the arteries. A heart attack results from a sudden plaque rupture and formation of a thrombus (blood clot) that completely blocks blood flow to a portion of the heart, leading to tissue death (infarct). CAD can also result in heart failure or arrhythmias. Heart failure is caused by chronic oxygen deprivation due to reduced blood flow, which weakens the heart over time. Arrhythmias are caused by inadequate blood supply to the heart that interferes with the heart's electric impulse. The coronary arteries can constrict as a response to various stimuli, mostly chemical. This is known as a coronary reflex. There is also a rare condition known as spontaneous coronary artery dissection, in which the wall of one of the coronary arteries tears, causing severe pain. Unlike CAD, spontaneous coronary artery dissection is not due to plaque buildup in arteries, and tends to occur in younger individuals, including women who have recently given birth or men who do intense exercise. Coronary artery dominance is described as the coronary artery that give branches to supply the right posterior descending artery and supplies the inferior wall of the heart. In 80 to 85% of the population, the right coronary artery supplies the posterior descending artery, making it right heart dominant while in 7 to 13% of the population, the left coronary artery supplies the posterior descending artery, making it left heart dominant. In 7 to 8% of the population, both right and left coronary arteries supplies the posterior descending artery, making it right and left co-dominance. Narrowing of coronary arteries is more frequent in those who are left dominant when compared to those who have right dominant or co-dominant hearts. ==Name etymology==

The word '''' is a Latin word that means "crown", from the Ancient Greek (, "garland, wreath"). It was applied to the coronary arteries because of a notional resemblance (compare the photos). The word arterie in Anglo-French (' in Old French, and ' in Latin) means "windpipe" and "an artery". It was applied to the coronary arteries because the arteries do not contain blood after death. == See also ==