Septal leaflet of right atrioventricular valve

The tricuspid valve (valvula tricuspidalis) consists of three somewhat triangular cusps or segments.

The largest cusp is interposed between the atrioventricular orifice and the conus arteriosus and is termed the anterior or infundibular cusp. A second, the posterior or marginal cusp, is in relation to the right margin of the ventricle, and a third, the medial or septal cusp, to the ventricular septum.

The septal leaflet of the right atrioventricular valve is the smallest of the three principal leaflets of tricuspid valve and is located medially, adjacent to the interventricular septum. It arises from the septal portion of the tricuspid annulus, which is more fibrous and relatively fixed compared to the free wall segments. The septal leaflet is supported by multiple chordae tendineae that attach either directly to the interventricular septum or to small, variable septal papillary muscles. This unique pattern of chordal attachment distinguishes the septal leaflet from the anterior and posterior leaflets, which are primarily supported by the anterior and posterior papillary muscles, respectively.[1-3]

The septal leaflet typically occupies about one-third of the tricuspid annular circumference in the classic three-leaflet configuration, but anatomical variation is common, with up to 40% of hearts exhibiting four functional leaflets, often with duplication of posterior or septal components