The pulmonic valve divides the right ventricular outflow tract from the pulmonary artery. In normal conditions, the pulmonic valve prevents regurgitation of deoxygenated blood from the pulmonary artery back to the right ventricle. It is a semilunar valve with 3 cusps, and it is located anterior, superior, and slightly to the left of the aortic valve.
An image depicting the pulmonary valve can be seen below.
Heart valves, superior view.
Gross and Microscopic Anatomy
Like the aortic valve, the pulmonic valve is formed by 3 cusps, each with a fibrous node at the midpoint of the free edges (similar to the nodes of Aranti in the aortic valve) as well as lunulae, which are the thin, crescent-shaped portions of the cusps that serve as the coaptive surfaces of the valve. In contrast with the aortic valve, the cusps of the pulmonic valve are supported by freestanding musculature with no direct relationship with the muscular septum; its cusps are much thinner and lack a fibrous continuity with the anterior leaflet of the right atrioventricular (AV) valve (tricuspid valve).
The cusps of the pulmonic valve are defined by their relationship to the aortic valve and are thus termed anterior or nonseptal, right and left cusps. They can also be defined by their relationship to a commissure found in the pulmonic and aortic valves and hence termed right adjacent (right facing), left adjacent (left facing), and opposite (nonfacing).
The pulmonic valve, like the other 3 cardiac valves, is formed by endocardial folds that are supported by internal plates of dense collagenous and elastic connective tissue and are continuous with the cardiac skeleton.