Inferior leaflet of right atrioventricular valve

At a glance

English

Inferior leaflet of right atrioventricular valve

Latin (TA2)

Cuspis inferior valvae atrioventricularis dextrae

System

Heart

Region

Trunk

Side

Single, on the midline

About the inferior leaflet of right atrioventricular valve

The right atrioventricular valve, better known as the tricuspid valve, guards the opening between the right atrium and the right ventricle. It has three leaflets, named for where they sit around the ring: anterior, septal and inferior. The inferior leaflet was called the posterior leaflet in older texts; the newer name follows the convention that the underside of the heart rests on the diaphragm.

This leaflet hangs from the inferior part of the fibrous ring, along the junction of the valve with the diaphragmatic wall of the right ventricle. It is often the smallest of the three and is often scalloped into two or more small segments. Its free edge meets the anterior leaflet at one commissure and the septal leaflet at another. Like the others it is a thin fold of endocardium strengthened by a core of fibrous tissue, with a smooth atrial surface and a rougher ventricular surface where tendinous cords attach.

The chordae tendineae of the inferior leaflet come mainly from the inferior papillary muscle of the right ventricle, with some from the septal papillary muscles. Each papillary muscle sends cords to two neighbouring leaflets, so contraction of the muscles during systole pulls adjacent edges together and stops them being driven back into the atrium.

When the ventricle contracts, the three leaflets come together and close the orifice, so blood leaves only through the pulmonary valve. Leakage of the valve, tricuspid regurgitation, is most often caused by stretching of the ring when the right ventricle is enlarged, rather than disease of the leaflets themselves. The inferior leaflet lies close to the opening of the coronary sinus and the path of the right coronary artery, which matters in valve surgery.

Function and supply

Begins at

The inferior part of the fibrous ring of the right atrioventricular orifice.

Ends at

Its free margin and ventricular surface are held by chordae tendineae from the inferior and septal papillary muscles of the right ventricle.

Function

Closes with the anterior and septal leaflets during ventricular systole to stop blood flowing back into the right atrium; opens in diastole to let the ventricle fill.