Patient Data Select from Choices to complete the sentence. Heart sounds are loudest for S1 and S2 at the ______.

The S1 sound, caused by the closure of the mitral and tricuspid valves, is best heard at the apex of the heart, located in the left fifth intercostal space at the midclavicular line. The S2 sound, caused by the closure of the aortic and pulmonic valves, is also prominent at the apex but can also be heard at the base of the heart, particularly over the aortic and pulmonic areas.