Pulmonary valve (anatomy)

The pulmonary valve is the heart valve between the right ventricle and the pulmonary trunk. It consists of three semi-lunar leaflets or cusps which project into the pulmonary trunk:

• anterior
• left
• right

It lies slightly anterosuperior to the aortic valve at the superior end of the infundibulum of the right ventricle; this is roughly the level of the left third costal cartilage. Its plane faces posterosuperior and to the left. The diameter of the valve is 2-3cm.

Each valve cusp is characterised by:

• a central layer of collagen, the lamina fibrosa
• a thickening of the lamina fibrosa at the free margin of each leaflet - the nodulus
• regions lateral to the nodulus of each valve termed the lunules
• a layer of endocardium completely covering the valve
• an attachment between the lamina fibrosa and the pulmonary valve annulus, part of the fibrous skeleton of the heart
• a dilation of the wall of the pulmonary trunk immediately superior to each cusp - the sinuses of Valsalva; each sinus fills with blood, so preventing the valve leaflet from adhering to the wall of the pulmonary trunk with consequent valvular incompetence