Which structure anchors AV valve leaflets to prevent prolapse during systole?

• A. Aortic valve leaflets
• B. Chordae tendineae and papillary muscles
• C. Interventricular septum
• D. Pulmonary valve leaflets

Answer: (B)

During systole, the atrioventricular valves must stay closed and prevent backflow into the atria. This is achieved by the chordae tendineae, thin tendinous cords that attach the valve leaflets to papillary muscles deep in the ventricular wall. When the ventricle contracts, the papillary muscles contract as well, pulling on the chordae and keeping the leaflets pulled tight and coapted so they don’t prolapse into the atria. If this tethering system fails—such as from chordae rupture or papillary muscle dysfunction—the leaflets can billow backward, causing regurgitation. The other structures listed are not responsible for anchoring AV valve leaflets: they pertain to the semilunar valves or are simply parts of the ventricular wall, not the tethering mechanism for the AV valves.