The five traditionally designated auscultatory areas are:

1. Aortic area: This area is located on the right side of the sternum, in the second intercostal space. The aortic valve is located here, and auscultation of this area can reveal aortic stenosis, aortic insufficiency, and aortic regurgitation.
2. Pulmonic area: This area is located on the left side of the sternum, in the second intercostal space. The pulmonic valve is located here, and auscultation of this area can reveal pulmonic stenosis and pulmonic insufficiency.
3. Tricuspid area: This area is located on the lower left sternal border, in the fourth and fifth intercostal spaces. The tricuspid valve is located here, and auscultation of this area can reveal tricuspid stenosis and tricuspid insufficiency.
4. Mitral area: This area is located at the apex of the heart, in the fifth intercostal space, medial to the midclavicular line. The mitral valve is located here, and auscultation of this area can reveal mitral stenosis and mitral insufficiency.
5. Erb’s point: This area is located in the third left intercostal space, lateral to the sternum. The pulmonary artery and aortic arch cross each other at this point, and auscultation of this area can reveal splitting of the second heart sound.

Why are heart sounds heard in these areas?

The heart sounds are produced by the closure of the heart valves. The aortic and pulmonic valves close during the second heart sound, and the tricuspid and mitral valves close during the first heart sound. The heart sounds are best heard at the areas where the valves are located.

The aortic valve is located on the right side of the sternum, in the second intercostal space. This is because the aorta exits the heart on the right side. The pulmonic valve is located on the left side of the sternum, in the second intercostal space. This is because the pulmonary artery exits the heart on the left side.

The tricuspid valve is located on the lower left sternal border, in the fourth and fifth intercostal spaces. This is because the tricuspid valve is located on the right side of the heart, and the heart rotates to the left as it descends. The mitral valve is located at the apex of the heart, in the fifth intercostal space, medial to the midclavicular line. This is because the mitral valve is located on the left side of the heart.

Erb’s point is located in the third left intercostal space, lateral to the sternum. This is where the pulmonary artery and aortic arch cross each other. The splitting of the second heart sound is heard at this point because the pulmonary valve closes slightly before the aortic valve.

Conclusion

The five traditionally designated auscultatory areas are the aortic area, pulmonic area, tricuspid area, mitral area, and Erb’s point. These areas are important for auscultation because they are where the heart valves are located. The heart sounds are produced by the closure of the heart valves, and they are best heard at the areas where the valves are located.