Question

S1 is heard best at the?

1) 5th ICS left midclavicular line
2) 3rd ICS left midclavicular line
3) 2nd ICS right sternal border
4) 2nd ICS left sternal border

Answer 1

The S1 heart sound is best heard at the 5th intercostal space (ICS) at the left midclavicular line. This location is over the apex of the heart, where the closure of the mitral valve can be most clearly auscultated.

Step-by-step explanation:

S1, the first heart sound, is best heard at the 5th intercostal space (ICS) at the left midclavicular line. This heart sound results from the closure of the atrioventricular valves (the mitral and tricuspid valves) during ventricular contraction. Proper placement of the stethoscope is critical for auscultation, and according to cardiac physiology, the bell of the stethoscope should be placed where the valve sounds are best transmitted.

The 5th ICS at the left midclavicular line is directly over the apex of the heart, where the mitral valve sound is transmitted most clearly. It’s important to note that S2, the second heart sound, is best heard at the 2nd ICS right sternal border for the aortic valve and the 2nd ICS left sternal border for the pulmonary valve.