QS Study

The left coronary artery is one of the two main arteries that supply the heart with oxygenated blood. This artery supplies blood to the outer side and back of the heart.

Origin – Left posterior aortic sinus of the ascending aorta. It is a branch of the ascending aorta, with its normal origin in the left aortic sinus, just superior to the aortic valve.


The artery passes forward between the pulmonary trunk and the left auricle.

It then enters the atrioventricular groove and divides into an anterior interventricular branch & a circumflex branch.

The anterior interventricular branch runs downward to the apex of the heart in the anterior interventricular groove. It then passes around the apex to anastomose with the posterior interventricular branch of the right coronary artery.

Fig: Left Coronary Artery

Branches of the left coronary artery

(1) Anterior interventricular artery:

a) Ventral branches (Diagonal artery, left coitus artery)

b) Septal rami.

(2) Circumflex artery:

a) Left marginal artery.

b) Anterior and posterior ventricular branches,

c) Left posterior inter-ventricular artery.

d) Artery to the sinuatrial node.

e) Kugel’s anastomotic artery.

Area of distribution – The left coronary artery, which branches into the left anterior descending artery and the circumflex artery, supplies blood to the left side of the heart.

  • Left atrium.
  • Left ventricle except for a strip along the posterior & inferior surfaces of the heart.
  • A small part of the right ventricle adjoining the anterior inter-ventricular groove.
  • Antero-superior 1/3 rd interventricular septum.
  • A part of the left branch of A.V bundle and in 35% cases S.A node.
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