QS Study

Distribution of the Coronary Arteries

When the heart is relaxed, the back-flow of blood fills these valve pockets, therefore allowing blood to enter the coronary arteries. In general, the area of the heart which an artery passes over will be the area that it perfuses. The following describes the anatomical course of the coronary arteries.

Right coronary artery supplies the whole of the right atrium, most of the right ventricle except a strip along the anterior interventricular groove, posteroinferior one-third of the ventricular septum, and S. A. node and A.V. node in the majority of subjects. It branches to form the right marginal artery (RMA) anteriorly. In 80-85% of individuals, it also branches into the posterior interventricular artery (PIv) posteriorly.

Left coronary artery supplies most of the left atrium and left ventricle except a strip along the posterior and inferior surfaces of the heart, and also supplies antero-superior two – thirds of the ventricular septum. The LCA also gives off the left marginal artery (LMA) and the left circumflex artery (Cx). In ~20-25% of individuals, the left circumflex artery contributes to the posterior interventricular artery (PIv).

Venous drainage

  • 60% of venous blood drain into — right atrium via coronary sinus.
  • 40 % of venous blood drain into — different chambers of the heart via venae cordis minimi & anterior cardiac vein.

The aortic sinuses are small openings found within the aorta behind the left and right flaps of the aortic valve.

Tributaries of the coronary sinus

Coronary sinus:

  1. Great cardiac vein: In anterior interventricular groove.
  2. Middle cardiac vein: In posterior intreventricular groove.
  3. Small cardiac vein: Lies in the right posterior coronary sulcus.
  4. Posterior vein of the left ventricle: Drain from the inferior surface of the left ventricle.
  5. Oblique vein of left atrium: Drain from the posterior surface of the left atrium.
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