1. When referring to the "main" coronary artery, that is usually refers to the left main (lm) coronary artery. This artery divides quickly into the left anterior and left cicumflex artery, both very important and large conduits supplying much of the heart muscle with blood. The right coronary artery usually has its own origin. In some people there is no lm and each artery has its origin off the aorta.
2. Left and right coronary arteries.
Coronaries. 4 main coronaries: the left main, left anterior descending, left circumflex and the right coronary artery.