Coronary Artery Anatomy 
 
The coronary circulation provides oxygen and nutrients to the heart muscle (myocardium). It originates from the ascending aorta, just above the aortic valve, via the right and left coronary arteries. 
 
1. Coronary Arteries 
 
A. Left Coronary Artery (LCA) 
 
Origin: Left aortic sinus, part of the ascending aorta, just above the left cusp of the aortic valve. 
Course: Passes between the pulmonary trunk and the left atrial appendage, then divides into its branches. 
 
Main branches: 
 
Left Anterior Descending (LAD) artery (also called the anterior interventricular artery): 
 
Runs in the anterior interventricular groove toward the apex of the heart. 
Supplies: 
Anterior wall of left ventricle 
Anterior 2/3 of interventricular septum 
Apex of the heart 
Major branches: 
Diagonal branches → anterior LV wall 
Septal perforators → anterior septum 
 
Left Circumflex (LCx) artery: 
Courses in the left atrioventricular (AV) groove. 
Supplies: 
Lateral and posterior walls of the left ventricle 
Left atrium 
Major branches: 
Obtuse marginal arteries → lateral LV wall 
 
(Sometimes: A left posterior descending artery (LPDA) arises from the LCx in left-dominant circulation (see dominance below)). 
 
B. Right Coronary Artery (RCA) 
 
Origin: Right aortic sinus, part of the ascending aorta, just above the right cusp of the aortic valve. 
Course: Travels in the right AV groove toward the crux cordis of the heart (the area at the back of the heart where the AV groove and IV groove meet). 
 
Main branches: 

Conus branch → supplies the right ventricular outflow tract (RVOT) 
Sinoatrial (SA) nodal branch → supplies the SA node (in ~60% of people) 
Right marginal (acute marginal) artery → supplies right ventricle 
Posterior descending artery (PDA) → supplies posterior 1/3 of interventricular septum (in right-dominant hearts) 
AV nodal artery → supplies AV node (~80% of people) 
 
2. Coronary Dominance 
 
This term is used to define the artery giving rise to the posterior descending artery (PDA): 
 
Right dominance (in ≈ 70–85% of people) → PDA from RCA 
Left dominance (≈ 10–15%) → PDA from LCx 
Co-dominance (≈ 5–10%) → PDA from both RCA and LCx