CVS Practice Test

The posterior (medial) papillary muscle is primarily supplied by the posterior descending artery (PDA). This artery branches off from the right coronary artery in most individuals, although in some cases it can arise from the circumflex artery, especially in left-dominant coronary systems.

The PDA provides blood to the inferior and posterior parts of the heart, including the walls of the left ventricle and the interventricular septum, areas that are crucial for the function of the papillary muscles. Since the posterior papillary muscle is located more toward the back of the heart, it relies on this specific artery for its blood supply, making the PDA essential for maintaining the muscle's health and functionality in supporting the mitral valve.

Other options indicate different coronary arteries that generally supply more anterior areas of the heart or do not directly supply the papillary muscles. The anterior descending artery is involved with the anterior aspects of the heart, the circumflex artery primarily supplies the lateral walls, and the coronary sinus serves as a collection point for deoxygenated blood rather than a direct supplier of blood to myocardial structures.