The heart pumps to supply the rest of the body with oxygenated blood. It also supplies itself with this blood, however, by using the coronary arteries, which exist on the epicardium.
The primary arteries emanate from the left and right coronary cusps. The right coronary artery extends from the right coronary cusp, and from the left, the Left Main Stem (LMS) divides into the Left Anterior Descending (LAD), and Left Circumflex Artery (LCx).
From these arteries, further divisions can be found:
LAD – Supplies the anterior and apical LV, and the anterior septum
Diagonal branches (D1, D2)
Septal branches
LCx – Supplies the lateral and posterior LV, and the LA
Marginal branches (M1, M2)
RCA – Supplies the RA, RV, posterior septum, and a portion of the apical LV
Acute marginal branch (AM)
AV node branch
Posterior descending branch (PDA)
The Student Physiologist 