Pulmonary valve
Valva trunci pulmonalis
Definition
The pulmonary valve (valva trunci pulmonalis) is the semilunar valve located between the right ventricle and the pulmonary trunk in regards of opening of pulmonary trunk.
The pulmonary valve lies at the junction of the right ventricular outflow tract (conus arteriosus) and the pulmonary trunk. It prevents backflow of blood from the pulmonary trunk into the right ventricle during diastole.
It consists of three semilunar cusps attached to a fibrous ring (annulus fibrosus), forming part of the cardiac fibrous skeleton:
At the free edge of each cusp a central thickening forms the nodule (nodulus valvulae semilunaris) and thin marginal areas on either side are called lunulae. When the valve closes, the nodules meet centrally, and the lunulae ensure tight apposition, preventing regurgitation.
Behind each cusp is a dilation of the pulmonary trunk wall called a pulmonary sinus (sinus of the pulmonary trunk). These sinuses allow the cusps to open fully during systole without obstructing blood flow.
During systole, right ventricular contraction forces cusps against the pulmonary trunk wall and blood flows into the pulmonary trunk
During diastole, backflow fills the pulmonary sinuses, cusps inflate and coapt centrally and nodules and lunulae seal the orifice
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