Where is S2 heard the loudest?

Where is S2 heard the loudest?

• A. Base of the heart
• B. Apex of the heart
• C. Left lower sternal border
• D. Right atrial border

Answer: (A)

S2 is the sound of the semilunar valves (aortic and pulmonic) shutting. It is heard loudest at the base of the heart because that region over lies the valve closures high in the chest, where the aortic and pulmonic areas are located. The base—around the right and left second intercostal spaces near the sternal border—receives the most intense transmission of that high-pitched, sharp sound, so S2 stands out there. In normal adults, A2 is usually louder than P2, and you can often hear both components together or as a split sound at the base, especially with inspiration. By contrast, the apex is where S1 and possibly low-frequency sounds (like S3/S4) are more prominent, and the other borders are not the typical sites for the loudest S2.

S2 is the sound of the semilunar valves (aortic and pulmonic) shutting. It is heard loudest at the base of the heart because that region over lies the valve closures high in the chest, where the aortic and pulmonic areas are located. The base—around the right and left second intercostal spaces near the sternal border—receives the most intense transmission of that high-pitched, sharp sound, so S2 stands out there. In normal adults, A2 is usually louder than P2, and you can often hear both components together or as a split sound at the base, especially with inspiration. By contrast, the apex is where S1 and possibly low-frequency sounds (like S3/S4) are more prominent, and the other borders are not the typical sites for the loudest S2.