Tendon of Todaro

Chordae tendineae
The chordae tendineae are the tendons connecting the valves to the heart muscle
Papillary muscles and chordae tendineae
Details
Identifiers
Latin	chordae tendineae cordis
MeSH	A07.541.510.240
Dorlands /Elsevier	c_31/12236883
TA	A12.1.00.023
FMA	76527
Anatomical terminology []

The chordae tendineae (tendinous chords), colloquially known as the heart strings, are cord-like tendons that connect the papillary muscles to the tricuspid valve and the mitral valve in the heart.

Chordae tendineae are approximately 80% collagen, while the remaining 20% is made up of elastin and endothelial cells.

The tendon of Todaro is a continuation of the Eustachian valve of the inferior vena cava and the Thebesian ring of the coronary sinus. Along with the opening of the coronary sinus and the septal cusp of the tricuspid valve, it makes up the triangle of Koch. The apex of the triangle of Koch is the location of the atrioventricular node.

During atrial systole, blood flows from the atria to the ventricles down the pressure gradient. Chordae tendineae are relaxed because the atrioventricular valves are forced open.

When the ventricles of the heart contract in ventricular systole, the increased blood pressures in both chambers push the AV valves to close simultaneously, preventing backflow of blood into the atria. Since the blood pressure in atria is much lower than that in the ventricles, the flaps attempt to evert to the low pressure regions. The chordae tendineae prevent the eversion, prolapse, by becoming tense thus pulling the flaps, holding them in closed position.

Papillary muscles and chordae tendineae

Ultrasound showing redundant chordae tendineae