tendineae

Tendineae, commonly known as chordae tendineae, are slender, cord-like structures inside the heart that connect the atrioventricular valve leaflets to the papillary muscles within the ventricles. They are primarily composed of dense connective tissue rich in collagen fibers.

In humans, the chordae extend from the free edges and ventricular surfaces of the mitral and tricuspid valve leaflets to the papillary muscles. The leaflets of the left-sided mitral valve typically have a greater number of chordae than the right-sided tricuspid valve, reflecting differences in their mechanical demands. Chordae can be classified as primary (marginal) chordae, which anchor at the leaflet margins, as well as secondary chordae that attach to the leaflet surfaces or to the ventricular wall and papillary muscles.

During systole, the papillary muscles contract and tense the chordae. This tension prevents the valve leaflets from prolapsing back into the atria, ensuring proper coaptation and preventing regurgitation. The chordae thus contribute to valve competence and the overall efficiency of ventricular ejection.

Clinical relevance includes conditions such as chordae rupture or elongation, which can cause acute or chronic mitral or tricuspid regurgitation. Rupture is most famously associated with myocardial infarction and can lead to sudden heart failure if not treated. Chordae may also be addressed in valve repair or replacement procedures when disease is present.

Etymology derives from Latin, meaning tendinous cords.