Left coronary artery

The left coronary artery (LCA, Latin: arteria coronaria sinistra) is a branch of the ascending aorta that is one of the main branches that supplies the heart with oxygenated blood. 

The LCA arises from the left semilunar cusp (sinus of Valsalva). The initial segment of the artery ends at its first bifurcation, where it divides into the left anterior interventricular artery and the left circumflex artery

The artery passes between the left atrial (auricular) appendage and the pulmonary trunk. As it enters the left half of the sternocostal atrioventricular groove, the LCA turns left toward the obtuse margin of the heart. 

Before its bifurcation, the initial portion of the left coronary artery usually has no branches arising from it. Sometimes it gives off a small sinoatrial node artery and an atrial ramus.

The left coronary artery supplies the left atrium, most of the left ventricle, and the majority of the interventricular septum.

The left coronary artery splits into the anterior interventricular artery (also known as the left anterior descending artery) and the left circumflex artery.

Anterior interventricular artery

The anterior interventricular artery travels within the anterior interventricular groove inferolaterally. It gives off the following branches: 

  • left conus artery
  • anterior ventricular arteries (as many as nine of them), 
  • anterior septal arteries
  • posterior ventricular branch, and 
  • septal branch.  

This vessel may terminate at the cardiac apex. Still, more often, it continues onto the diaphragmatic surface and meets the terminal branches of the posterior descending artery, which arises from the right coronary artery.

Left circumflex artery

The left circumflex artery takes a left course in the atrioventricular groove while being overlapped by the left atrial (auricular) appendage. It then crosses over the obtuse border of the heart. The artery may give rise to atrial branches (posterior, lateral, and anterior divisions) that supply the left atrium. 

Other branches of the left circumflex artery include: 

  • Kugel`s anastomotic artery to provide anastomotic pathways between the right and left coronary arteries;
  • left marginal branch to supply the diaphragmatic part of the left ventricle;
  • anterior and posterior ventricular arteries to supply the left ventricle.