Branches of the Coronary Arteries

• Conus branch: The first branch of the right coronary artery (RCA) in about 50% of cases. Courses anteriorly to supply the right ventricular outflow tract. Can also arise from the left main coronary artery (LM) or have a common origin with the RCA.
• Sinoatrial nodal artery (SAN): Usually the second branch of the RCA. Courses toward the superior vena cava inflow near the cephalad aspect of the interatrial septum. Can also arise from the proximal left circumflex coronary artery (LCx).
• Acute marginal branches: Arise from from the RCA and supply the anterior right ventricular wall.
• Posterior descending artery (PDA): Also known as the posterior interventricular artery. Arises from the RCA in the majority of cases. Runs in the inferior interventricular groove and supplies the diaphragmatic surface of the ventricles and part of the interventricular septum.
• Posterior left ventricular artery (PLV): Also known as the posterolateral branch. Arises from the RCA in the majority of cases. Supplies the inferior left ventricular wall.
• Septal perforators: Arise from the left anterior descending (LAD) artery and supply the anterior ventricular septum.
• Diagnonal branches: Arise from the LAD artery and supply the anterior wall of the left ventricle.
• Ramus intermedius: The most common variation in left coronary anatomy. A third branch that arises between the LAD and LCx at the distal left main coronary artery. The ramus intermedius artery may supply the anterior or the lateral wall of the left ventricle depending on its course.
• Obtuse marginal branches: Arise from the LCx and supply the lateral wall of the left ventricle.

The origin of the PDA determines dominance. In a right-dominant heart, the PDA is supplied by the RCA. In a left dominant heart the PDA is supplied by the LCx. In a co-dominant heart, the PDA is supplied by the RCA and the PLV is supplies by the LCx.

References

• Kini S, Bis KG, Weaver L. Normal and variant coronary arterial and venous anatomy on high-resolution CT angiography. AJR Am J Roentgenol. 2007 Jun;188(6):1665-74.
• Abbara S and Achenbach S. Chapter 8: Coronary Computed Tomography Angiography. in Cardiac Imaging: The Requisites (third ed). Miller SW et al (eds).