Tricuspid valve

Where is the tricuspid valve?

It is the largest of the heart valves and the one set closest to the apex. Its normal area is 7 to 9 cm². (StatPearls, Tricuspid Valve Repair)

The right atrium above it collects blood from the superior and inferior venae cavae and from the coronary sinus, which drains the heart muscle. (OpenStax A&P 2e, 19.1; StatPearls, Heart)

Its closing is heard loudest in the fourth left intercostal space. (StatPearls, Heart Sounds)

What are the parts of the tricuspid valve?

Its three leaflets are the anterior, the posterior and the septal. The anterior is the largest and moves the most, the septal moves the least, and the posterior is the shortest around the ring. (StatPearls, Tricuspid Valve Repair)

Chordae tendineae tie the flaps to papillary muscles in the right ventricle. The cords are made mainly of dense regular connective tissue with collagen and elastic fibers. (OpenStax A&P 2e, 19.1; StatPearls, Histology, Heart)

Its annulus is a D-shaped ring that moves with the heart. The longer, C-shaped part follows the free wall of the right ventricle, and the shorter, straighter part lies along the septum. (StatPearls, Tricuspid Valve Repair)

What does the tricuspid valve do?

While the heart relaxes, blood from the right atrium flows through the open valve into the right ventricle. (OpenStax A&P 2e, 19.3 and 19.1; StatPearls, Heart and Pericardial Cavity)

When the right ventricle contracts, its papillary muscles contract too and pull on the chordae. That stops the flaps from being forced into the atrium and blood from flowing back. (OpenStax A&P 2e, 19.1; Gray 1918, 4b. The Heart)

Its closure, with the mitral valve’s, makes the first heart sound, S1. At rest the two closures come too close together to tell apart. (StatPearls, Heart Sounds)

The mean pressure difference across the valve is less than 2 mm Hg, because the valve is large and pressures on the right side of the heart are low. (StatPearls, Tricuspid Valve Repair)

What lies around the tricuspid valve?

The right ventricle has three papillary muscles. The anterior, the largest, rises from the anterior wall, the posterior from the inferior wall, and the septal, the smallest, from the interventricular septum. (StatPearls, Heart Papillary Muscles)

Its septal leaflet attaches to the septum less than 10 mm nearer the apex than the anterior leaflet of the mitral valve. (StatPearls, Tricuspid Valve Repair)

The tricuspid valve forms one side of the triangle of Koch, with the tendon of Todaro and the lip of the coronary sinus opening. The atrioventricular node lies in that triangle. (StatPearls, Heart)

A muscular fold, the ventriculoinfundibular fold, separates it from the pulmonary valve. (StatPearls, Heart Pulmonic Valve)

Does the tricuspid valve vary?

Valves with two cusps, and valves with more than three, have been reported. (StatPearls, Tricuspid Valve Repair)

Where the sources differ

Sources differ on the number of papillary muscles. OpenStax and the StatPearls article on papillary muscles give the right ventricle three, the anterior, posterior and septal. The StatPearls article on tricuspid valve repair says the usual count is two, the anterior and posterior, with a third, septal muscle that varies. (OpenStax A&P 2e, 19.1; StatPearls, Heart Papillary Muscles and Tricuspid Valve Repair)