Left Semilunar Leaflet of the Pulmonary Valve Transverse View

Description

Arising from the right ventricular outflow tract, the pulmonary trunk is opened in transverse section to expose the pulmonary valve, with emphasis on the left semilunar leaflet (valvula semilunaris sinistra). The leaflet’s thin, concave ventricular surface faces inferiorly toward the infundibulum, while its convex arterial surface lies superiorly toward the pulmonary sinus and the lumen of the pulmonary trunk. At the free margin, the lunula arcs toward the commissures, and the central nodule provides coaptation against the adjacent anterior and right leaflets. Orientation is keyed to anatomical position: the highlighted left leaflet sits leftward and slightly posterior relative to the other cusps. This transverse cut is the clearest way to teach cusp geometry and valve competence at the level where surgeons and imagers mentally place the annulus and sinuses. Pulmonary valve pathology often gets framed as a right-sided problem, but cusp morphology matters when evaluating congenital pulmonary stenosis, dysplastic leaflets, or postoperative regurgitation after repair of tetralogy of Fallot. Short-axis echocardiography and gated CT/MR routinely approximate this plane, so understanding which cusp is which prevents laterality errors during reporting and intervention planning. Clean closure depends on it. Use this asset in cardiothoracic anatomy and embryology modules when covering conotruncal development and semilunar valve formation, or in adult cardiology teaching sets that compare aortic versus pulmonary valve anatomy. It also fits operative atlases and device-focused publications discussing balloon valvuloplasty, transcatheter pulmonary valve implantation, and revision of the right ventricular outflow tract with attention to commissural alignment. Anatomical accuracy verified by SciePro's Medical Advisory Board.