The triangle of auscultation is a relative thinning of the musculature of the back, situated along the medial border of the scapula which allows for improved listening to the lungs.

It has the following boundaries: The superficial floor of the triangle is formed by the lateral portion of the erector spinae muscles.

[1] Due to the relative thinning of the musculature of the back in the triangle, the posterior thoracic wall is closer to the skin surface, making respiratory sounds audible more clearly with a stethoscope.

In days before X-rays were discovered, the sound of swallowed liquids were auscultated over this triangle to confirm an oesophageal tumour.

To better expose the floor of the triangle up of the posterior thoracic wall in the 6th and 7th intercostal space, a patient is asked to fold their arms across their chest, laterally rotating the scapulae, while bending forward at the trunk, somewhat resembling the fetal position.