one of two blood vessels that branch from the aorta close to its point of departure from the heart and carry oxygen-rich blood to the heart muscle. Both arteries supply blood to the walls of both lower chambers (ventricles) and to the partition between the chambers. The right coronary artery supplies blood to the right upper chamber (atrium), while the left supplies the left atrium. Blockage of any branch of the coronary arteries causes death of a portion of the heart tissue when it is deprived of oxygen-rich blood (see coronary heart disease).