What is the role of papillary muscles in valve function?

• A. They generate the heartbeat.
• B. They contract to tighten the chordae tendineae, preventing valve cusps from everting.
• C. They open the AV valves during relaxation.
• D. They separate oxygenated and deoxygenated blood.

Answer: (B)

The key function of papillary muscles is to keep the atrioventricular valves closed during ventricle contraction. They are connected to the valve leaflets (especially the mitral and tricuspid valves) by the chordae tendineae. When the ventricle contracts, the papillary muscles also contract and pull on the chordae, which tightens the leaflets and prevents them from bulging backward into the atria. This action stops blood from flowing backward (regurgitation) as the ventricular pressure rises.

This is different from what generates the heartbeat—that’s the heart’s electrical conduction system—and from what opens the AV valves, which occurs when the ventricles relax and pressure falls, allowing forward flow. Separating oxygenated from deoxygenated blood is a broader cardiac function involving the chambers and circulation, not the papillary muscles themselves.