papillary muscle - any of several muscles associated with the atrioventricular valves; "the papillary muscles contract during systole to prevent regurgitation of blood into the atria"

bicuspid valve, left atrioventricular valve, mitral valve - valve with two cusps; situated between the left atrium and the left ventricle

right atrioventricular valve, tricuspid valve - valve with three cusps; situated between the right atrium and the right ventricle; allows blood to pass from atrium to ventricle and closes to prevent backflow when the ventricle contracts

cardiac valve, heart valve - a valve to control one-way flow of blood