The left coronary artery is an artery arising from the ascending aorta and giving off the ventral or left interventricular artery and a circumfex branch. Its origin is either in the left adjacent or left posterir aortic sinus. After running for a short distance beneath the left auricula it splits into the ventral or left interventricular artery and the circumflex branch The ventral or left interventricular artery (aka: anterior interventricular artery, ramus interventricularis anterior arteriae coronariae sinistrae, anterior descending artery) runs to the left betwene the pulmonary trunkand left auricula, arriving at the ventral interventricular sulcus which it follws to the apex, where it provides branches to the right and left ventricules. The circumflex branch (aka: ramus circumflexes, ramus circumflexus arteriae coronariae sinistrae) follows the coronary sulcus’s left part, going left and then right, and arriving almost at the posterior interventricular sulcus. It provides branches to the left atrium and left ventricle. In some patients, the left coronary artery or the ventral/left interventricular artery is given off by the left pulmonary artery and supplies the left ventricule. This condition usually results in death during infancy. In some cases the left coronary is a branch of the right coronary artery, and in others there is only one coronary artery or three, the extra one feeding the others’ branches. In half of patients the right coronary artery predominates, in one-third the right and left are equal, and in one-sixth the left one predominates. In seventy percent of patients the right coronary artery feeds the sinoatrial node, but in twenty-five percent it is fed by the left and in seven percent by both. The atrioventricular node is fed by the right coronary artery in ninety-two percent of cases.

Myocardial Bridge of the LAD

CTA of the Coronary Arteries
LAD

Circumflex

RCA 

RCA