Which cavity of the heart has the thickest wall?

The right atrium has a relatively thin muscular wall since its primary function is to receive deoxygenated blood from the body and funnel it into the right ventricle. It does not require the strength of a thicker wall, as it does not need to generate high pressure for blood circulation.

While the left atrium does have a thicker wall than the right atrium, it is still not as thick as that of the left ventricle. Its role is to receive oxygenated blood from the lungs and pass it to the left ventricle, requiring less muscular strength compared to the left ventricle's role in systemic circulation.

The right ventricle has a thicker wall than the atria, but it is significantly thinner than that of the left ventricle. This is because the right ventricle only needs to pump deoxygenated blood to the lungs, which requires less pressure than the left ventricle's function of pumping blood to the entire body.