Segments

• Proximal: starting at RCA origin, spanning half the distance to the acute margin^[6][7]
• Middle: from proximal segment to the acute margin^[6][7]
• Distal: from middle segment to origination point of the posterior interventricular artery, where the posterior interventricular sulcus meets the atrioventricular groove on the base of the heart.^[6][7]

Variation

In approximately 80% of patients (right dominant), the RCA gives off the posterior descending artery (PDA). In the other 20%, of cases (left dominant or codominant), the PDA arises from the left circumflex artery or is supplied by both the right coronary artery and the left circumflex.^[8] The PDA supplies the inferior wall, ventricular septum, and the posteromedial papillary muscle.^{[citation needed]}

The RCA also supplies the SA nodal artery in 60% of people. The other 40% of the time, the SA nodal artery is supplied by the left circumflex artery.^{[citation needed]}

Although rare, several anomalous courses of the right coronary artery have been described including origin from the left aortic sinus.^[9]

Distribution

The right coronary artery supplies oxygenated blood to the right atrium, the right ventricle, and the posterior third and inferior end of the interventricular septum.^[2][5] It may also supply 25% to 35% of the left ventricle (LV).^[10]

There is significant overlap of supply of the coronary arteries.^[2] The right coronary artery is dominant over the left coronary artery 50% of the time, equal to it 20% of the time, and less significant than it 30% of the time.^[2]