The heart is a powerful muscular pump that requires a constant, rich supply of oxygenated blood to maintain its non-stop function. Unlike other organs, the heart muscle (myocardium) must be fed by its own dedicated vessels called the coronary arteries. The arrangement of these arteries creates distinct geographical zones, or “coronary artery territories,” that map the structure of the heart. These territories represent specific regions of the muscle wall dependent on a single artery for survival. Understanding this anatomical map is fundamental to grasping how the heart functions and what happens when its blood supply is interrupted.
The Primary Coronary Arteries
The heart’s blood supply begins as blood exits the left ventricle and enters the aorta. The two main coronary vessels, the Left Main Coronary Artery (LMCA) and the Right Coronary Artery (RCA), branch off the aorta near its root. The LMCA is a short, wide vessel that quickly divides into its two primary branches.
This initial split determines the blood flow to the large, high-pressure left side of the heart. The two major divisions of the LMCA are the Left Anterior Descending (LAD) artery and the Left Circumflex (LCX) artery. The RCA travels along the groove between the right atrium and the right ventricle before giving off its own major branches.
Territories Supplied by the Left Coronary Artery
The Left Main Coronary Artery system supplies the majority of the left ventricle, the chamber that pumps blood to the rest of the body. The Left Anterior Descending (LAD) artery travels down the front surface of the heart, giving off small septal perforators and diagonal branches. The territory of the LAD includes the anterior wall of the left ventricle and the apex of the heart.
The septal perforator branches dive into the wall separating the lower chambers, supplying the anterior two-thirds of the interventricular septum. A blockage high up in the LAD is often associated with extensive muscle damage due to this large area of supply. The diagonal branches supply the anterolateral wall of the left ventricle.
The second major branch, the Left Circumflex (LCX) artery, wraps around the left side of the heart between the left atrium and left ventricle. Its primary role is to supply the lateral and posterolateral walls of the left ventricle, often through obtuse marginal arteries. The LCX ensures that the side walls of the left ventricle receive the necessary oxygen and nutrients to contract effectively.
Territories Supplied by the Right Coronary Artery
The Right Coronary Artery (RCA) primarily supplies the right side of the heart, which handles the lower-pressure circulation of blood to the lungs. The RCA runs along the right side of the heart, supplying the right atrium and the right ventricle via branches like the acute marginal artery.
As the RCA continues around the back of the heart, it typically gives off the Posterior Descending Artery (PDA). The PDA supplies the inferior (bottom) wall of the left ventricle and the posterior one-third of the interventricular septum. The artery that gives rise to the PDA determines “coronary dominance”; the RCA is the source in approximately 90% of individuals, defining a right-dominant system.
A primary role of the RCA is its supply to the heart’s electrical conduction system. The RCA typically provides blood flow to the Sinoatrial (SA) node (the heart’s natural pacemaker) in about 60% of people. Furthermore, the RCA supplies the Atrioventricular (AV) node, which controls electrical signal passage between the upper and lower chambers, in about 90% of people.
Because of this electrical supply, a blockage in the RCA can cause profound disturbances in heart rhythm, in addition to muscle damage. The RCA territory includes the entire right ventricle, the inferior wall of the left ventricle, and the nodes that regulate the heart’s pace and rhythm.
Why Knowing the Territory Map Matters
The detailed map of coronary territories provides medical professionals with a powerful diagnostic tool, linking the location of muscle damage to the specific blocked artery. When a patient experiences a heart attack, the location of the injured muscle is identified using an electrocardiogram (ECG) and cardiac imaging. For instance, damage to the inferior wall of the left ventricle shows characteristic changes on an ECG.
An event affecting the anterior wall and septum strongly suggests an occlusion in the Left Anterior Descending (LAD) artery. By correlating the affected territory with the source vessel, doctors quickly identify the “culprit” artery responsible for the event. This anatomical knowledge guides immediate treatment decisions, such as which artery needs to be unblocked during an emergency procedure.
Modern cardiac imaging, such as magnetic resonance imaging (MRI) and computed tomography (CT) scans, further refines this territorial mapping. These technologies visualize the exact extent of muscle injury, confirming the vessel responsible for the lack of blood flow. Knowing which territory is compromised helps predict potential complications, such as rhythm problems from an RCA blockage or severe pump failure from extensive LAD territory damage.