The right atrioventricular valveor tricuspid valve (valvula tricuspidalis) consists of three somewhat triangular cusps or segments located in the right atrioventricular orifice, the large oval aperture of communication between the right atrium and ventricle.
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.
They are formed by duplicatures of the lining membrane of the heart, strengthened by intervening layers of fibrous tissue: their central parts are thick and strong, their marginal portions thin and translucent, and in the angles between the latter small intermediate segments are sometimes seen.
Their bases are attached to a fibrous ring surrounding the atrioventricular orifice and are also joined to each other so as to form a continuous annular membrane, while their apices project into the ventricular cavity.
Their atrial surfaces, directed toward the blood current from the atrium, are smooth; their ventricular surfaces, directed toward the wall of the ventricle, are rough and irregular, and, together with the apices and margins of the cusps, give attachment to a number of delicate tendinous cords, the chordæ tendineæ.