Mitral valve

Valva atrioventricularis sinistra (valva mitralis)

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What it is

The left atrioventricular valve, with a large anterior leaflet (continuous with the aortic valve) and a long, narrow posterior leaflet, tethered by chordae tendineae to two papillary muscles.

Function

Lets blood flow from the left atrium into the left ventricle and seals during systole so blood is ejected only into the aorta.

Size

Annulus ~3 cm diameter (circumference ~9–10 cm); opening area 4–6 cm².

Clinical note

Named for its resemblance to a bishop's mitre; mitral valve prolapse affects 2–3% of people, and rheumatic fever classically causes mitral stenosis.