Medial border of triangle of auscultation is
Triangle Of Auscultation It is a small triangular interval interval bounded medially by the lateral border of the trapezius, laterally by the medial border of the scapula,and inferiorly by the upper border of the latissimus dorsi.The floor of the triangle is formed by the seventh rib,sixth and seventh intercostal spaces,and the rhomboideus major. Ref.B D Chaurasia's human anatomy vol.1.
Trapezius
Scapula
Lattismus dorsi
Rhomboids major
Thorax