<P> The left and right coronary arteries occasionally arise by a common trunk, or their number may be increased to three; the additional branch being the posterior coronary artery (which is smaller in size). In rare cases, a person will have the third coronary artery run around the root of the aorta . </P> <P> Occasionally, a coronary artery will exist as a double structure (i.e. there are two arteries, parallel to each other, where ordinarily there would be one). </P> <P> The artery that supplies the posterior third of the interventricular septum--the posterior descending artery (PDA) determines the coronary dominance . </P> <Ul> <Li> If the posterior descending artery is supplied by the right coronary artery (RCA), then the coronary circulation can be classified as "right - dominant". </Li> <Li> If the posterior descending artery is supplied by the circumflex artery (CX), a branch of the left artery, then the coronary circulation can be classified as "left - dominant". </Li> <Li> If the posterior descending artery is supplied by both the right coronary artery and the circumflex artery, then the coronary circulation can be classified as "co-dominant". </Li> </Ul>

Which of the following are typically direct branches of the right coronary artery