Chordae tendineae play a crucial role in preventing the bicuspid (mitral) and tricuspid valves from collapsing back into the atria during powerful ventricular contractions.

Structure of the Chordae Tendineae:
Chordae tendineae are strong fibrous cords that connect the cusps of the atrioventricular valves (bicuspid and tricuspid valves) to the papillary muscles in the ventricles. The papillary muscles are small muscle projections from the ventricular walls. The chordae tendineae are attached to the edges of the cusps and extend downward to connect with the papillary muscles.

Function of the Chordae Tendineae:
The primary function of the chordae tendineae is to anchor the cusps of the atrioventricular valves to the papillary muscles. During ventricular contraction, the papillary muscles also contract, causing the chordae tendineae to tighten. This tension prevents the cusps of the valves from being forced back into the atria when the pressure in the ventricles increases during systole.

Preventing Valve Collapse:
When the ventricles contract (ventricular systole), the pressure inside the ventricles increases, causing the blood to be ejected into the pulmonary artery and aorta. This increase in pressure could potentially force the cusps of the valves back into the atria, leading to valve collapse and regurgitation of blood. However, the chordae tendineae prevent this from happening.

The tension in the chordae tendineae during ventricular contraction helps to keep the cusps of the valves in their proper position, ensuring a one-way flow of blood from the atria to the ventricles. By anchoring the valves to the papillary muscles, the chordae tendineae provide stability and prevent valve collapse, thus maintaining the integrity of the atrioventricular valves.

Conclusion:
In summary, the chordae tendineae prevent the bicuspid and tricuspid valves from collapsing back into the atria during powerful ventricular contractions. This is achieved by anchoring the cusps of the valves to the papillary muscles, creating tension in the chordae tendineae, and ensuring a one-way flow of blood from the atria to the ventricles.

This is the correct option. Bicuspid and tricuspid valves are prevented from collapsing back into the atria by the chordae tendineae during powerful ventricular contractions. In a heart, they occur in a group of tough, tendinous strands.