Basically, the triangle of auscultation is the region just medial to the inferior part of the scapula where large muscles fail to cover the rib cage. Due to the anatomical arrangement in this area, the diaphragm of a stethoscope can be placed close to the thoracic wall at this location. View the triangle of auscultation on dissected cadavers . The two primary sounds that we will be examining are the bronchial and vesicular breathing sounds. Bronchial sounds are produced by air moving through the trachea and bronchi.
Vesicular breathing sounds result from air filling the alveolar sacs.
Somewhere in between bronchial and vesicular breathing sounds are bronchiovesicular sounds, which are louder and harsher than normal vesicular sounds, but not as loud or harsh as the bronchial sound. There is no silent gap in a bronchiovesicular respiration. This gap is caused by the anatomical location of the normal bronchial sound, which can be heard over the lower portion of the trachea. Bronchial sounds come from the largest portion of the airway. This portion sits close to the chest wall, so emanating sounds are not muffled by lung tissue.