Blood Supply to the Heart
Even as the heart pumps blood to the rest of the body, it must supply adequate blood to its own walls as the muscles contract and relax, rhythmically and continuously. The circulation to the heart is known as the coronary circulation (see Figures 8.7 and 8.14), whichconsists of an extensive network of blood vessels.
The left and right coronary arteries are the first branches of the aorta, and they originate at the base of the ascending aorta. The right coronary artery fol-lows the coronary sulcus (sulcus, which demarcates the junction of the atria and ventricle) and gives off branches that supply the right atrium, ventricles, parts of the conducting system and descends posteri-orly between the two ventricles as theposterior in-terventricular branch, supplying the interventricu-lar septum. The left coronary artery supplies blood to the left ventricle, left atrium, and the interventricular septum. It also follows the coronary sulcus on the left side as the circumflex artery.Anteriorly, a large branch descends between the ventricles as the ante-rior interventricular branch.
Both coronary arteries have several communica-tions with each other, known as anastomoses. The arteries divide many times in the walls of the heart to form a network of capillaries. These capillaries even-tually form veins, which drain into the great cardiacvein.The great cardiac vein begins on the anteriorsurface of the ventricles along the interventricular sulcus and then travels in the coronary sulcus to reach the posterior aspect of the heart to drain into a larger vein, the coronary sinus. The coronary sinus drains into the right atrium.