The pulmonary valve is located at the junction of the distal end of the right ventricular outflow tract and the pulmonary artery. It is comprised of three semilunar leaflets, which are of equal dimensions. These leaflets are joined by three commissures, which are the attachments between the pulmonic wall and the leaflets. The pulmonic valve is not attached to papillary muscles, as we see with atrioventricular valves. The microscopic structure of the leaflets consists of five layers from ventricular end to arterial end are called: lamina ventricularis, lamina radialis, lamina spongiosa, lamina fibrosa, and lamina arterialis. The pulmonic valves help in delivering deoxygenated blood from the right ventricle to the lung vasculature during systole when they open completely. They close completely during diastole to prevent regurgitant flow. By far, the most common cause of pulmonic regurgitation (PR) is the dilation of the valve ring.
Pendela, Venkata Satish and Ayyad, Rania, "Pulmonic Regurgitation" (2021). Rochester Regional Health authored publications and proceedings. 239.