Coronary arteries

Coronary arteries supply the myocardium with oxygenated blood.

Right coronary artery

Arises directly from the right side of the aorta (specifically, from the right aortic sinus) and travels posteriorly within the coronary sulcus.
Branches:

• Sinoatrial nodal branch (aka, sinoatrial nodal branch).
• Right marginal branch.
• Posterior interventricular branch (aka, the PDA, posterior descending artery), which travels within the posterior interventricular groove (aka, sulcus).

Left coronary artery

Arises directly from the left side of the aorta and travels posteriorly within the coronary sulcus (the left coronary artery is sometimes referred to as the left main stem vessel).
Branches:

• Circumflex artery, which gives off the left marginal artery
• Anterior interventricular branch (aka, the LAD, left anterior descending artery), which travels within the anterior interventricular groove (aka, sulcus).

In general, the coronary arteries are functional end vessels, which means that there is little to no redundancy in the blood supply of the myocardium.
Two common exceptions to this rule:

• Anastomoses between the anterior and posterior interventricular arteries
• Anastomoses between the right and left coronary arteries

Anastomoses provide alternative pathways, called collateral channels, through which oxygenated blood can reach the myocardium.

Clinical correlations:

Occlusion (aka, blockage) of a coronary artery can cause ischemia and myocardial infarction (heart attack).
Treatments for coronary artery occlusion include:
Coronary angioplasty, in which the clogged artery is widened at the site of the obstruction.
Coronary artery bypass graft surgery, in which vascular segments from elsewhere in the body (eg, the great saphenous vein, internal thoracic arteries, or radial arteries) are grafted to the heart to circumvent the obstructed coronary arteries.