Coronary arteries

• Arise from the ascending aorta and are filled with blood during the ventricular diastole.
• Have maximal blood flow during diastole and minimal blood flow during systole because of compression of the arterial branches in the myocardium during systole.

• Arises from the anterior (right) aortic sinus of the ascending aorta, runs between the root of the pulmonary trunk and the right auricle, runs between the right auricle and the pulmonary trunk, and then descends in the right coronary sulcus, and generally supplies the right atrium and ventricle.

Gives rise to the following:

• Sinuatrial nodal artery
• Passes between the right atrium and the root of the ascending aorta, encircles the base of the SVC and supplies the SA node and the right atrium.
  

• Marginal artery
• Runs along the inferior border toward the apex and supplies the inferior margin of the right ventricle.
  

• Posterior IV (posterior descending) artery
• Is a larger terminal branch and supplies a part of the IV septum and left ventricle and the AV node.
  

• AV nodal artery
• Arises opposite the origin of its posterior IV artery and supplies the AV node.

• Arises from the left aortic sinus of the ascending aorta, just above the aortic semilunar valve.
• Is shorter than the right coronary artery and usually is distributed to more of the myocardium.

Gives rise to the following:

• Anterior IV (left anterior descending) artery
• Generally supplies anterior aspects of the right and left ventricles and is the chief source of blood to the IV septum and the apex.
  

• Circumflex artery
• Runs in the coronary sulcus, gives off the left marginal artery, supplies the left atrium and left ventricle, and anastomoses with the terminal branch of the right coronary artery.