The triangle of auscultation of the lungs is a relative thinning of the musculature of the back situated along the medial border of the scapula

Scapula

In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....

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Boundaries

It has the following boundaries:

• Superiorly and medially, by the inferior portion of the Trapezius
• Inferiorly, by the Latissimus dorsi
• Laterally by the medial border of the Scapula
  Scapula
  In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....
  
  

The superficial floor of the triangle is formed by the serratus anterior, rhomboid major, and the lateral portion of the erector spinae

Erector spinae

The Erector spinæ is a muscle group of the back in humans and animals. It is also known as sacrospinalis in older texts. A more modern term is extensor spinae, though this is not in widespread use. The name of the muscle is pronounced e-rec-tor speen-aye, or e-rec-tor spinae-ee.It is really not...

muscles. Deep to these muscles are the osseous portions of the 6th and 7th ribs and the internal and external intercostal muscles.

Function

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 able to be heard more clearly with a stethoscope.

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

External links

• Overview and diagram at ithaca.edu