Location:
The coronary arteries originate as the right and left main coronary arteries, which exit the ascending aorta just above the aortic valve (coronary ostia). There are three cusps of the aortic valve: the non-coronary cusp, which contains no ostia, the right coronary cusp, which contains the ostia of the right coronary artery, and the left coronary cusp, which contains the ostia of the left (main) coronary artery. The ostia of the left and right coronary arteries are located just above the aortic valve, as are the left and right sinuses of Valsalva.

Function:
Oxygenated blood is pumped into the aorta from the left ventricle; it then flows into the coronary artery ostia. Blood flow into the coronary arteries is greatest during ventricular diastole.