Where are flat sounds typically heard during percussion?

Flat sounds during percussion are typically heard over areas that contain dense tissue. In this context, hearing a flat sound over the sternum is indicative of the solid structure of the bone, which does not resonate like air-filled or fluid-filled areas. The sternum is a flat bone located in the center of the chest, and when percussed, it produces a flat sound due to its density and lack of air or fluid.

When comparing to the other options, notable differences arise. The lungs usually fill with air, leading to resonance sounds such as resonance or hyperresonance rather than flat sounds. The heart, while it is also a solid structure, is typically not percussed in isolation where flatness would be distinctly identified; rather, cardiac dullness may be noted due to the surrounding lung tissues and potential fluid. Over the stomach, one would expect to hear a tympanic sound due to the presence of gas in the gastrointestinal tract, which contrasts sharply with the flat sound expected over the sternum.