There are two main semilunar valves, each positioned at a critical exit point of the heart:

: Each valve typically consists of three thin, flexible leaflets (cusps) made of connective tissue and endocardium.

: Located between the right ventricle and the pulmonary artery . It directs deoxygenated blood toward the lungs for oxygenation. Structural Features

: 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

: These are small pockets behind the valve leaflets that help them close efficiently as blood pressure in the arteries rises.

: Located between the left ventricle and the aorta . It controls the flow of oxygen-rich blood to the rest of the body.

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

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