What are the semilunar valves?

The semilunar valves are the aortic and pulmonic valves, which play a critical role in the heart's function. They are located at the outflow of the ventricles, with the aortic valve situated between the left ventricle and the aorta, and the pulmonic valve located between the right ventricle and the pulmonary artery. These valves are designed to prevent the backflow of blood into the ventricles after contraction, thus ensuring efficient forward flow of blood to the systemic and pulmonary circulations.

The term "semilunar" refers to their crescent shape, resembling a half-moon. This shape is key to their functionality, allowing them to open when the ventricles contract (during systole) and close when the pressure drops in the ventricles (during diastole), preventing regurgitation of blood. Understanding the anatomy and function of these valves is essential for assessing cardiovascular health and managing conditions that may arise from valve dysfunction, such as stenosis or regurgitation.