Semilunar — Valve

: The sharp closure of these valves at the end of a heartbeat creates the second heart sound, commonly known as the "dub". What is the Pulmonary Valve? - Cleveland Clinic

The are pocket-like structures in the heart that act as one-way gates between the ventricles and the major arteries. Named for their crescent-moon or "half-moon" shape, they ensure that blood flows forward into the body and lungs without leaking back into the heart. Types of Semilunar Valves semilunar valve

: Unlike atrioventricular (AV) valves, semilunar valves do not have chordae tendineae (heart strings) or papillary muscles to hold them in place. : The sharp closure of these valves at