The rhomboids, serratus anterior, external obliques, and internal obliques are involved in the serape effect.
Rhomboid muscles | Adductor muscles of the hip | ''Spiral Expansion of Muscles in Action'', plaster, photograph published in 1914 and 1919, in ''Cubists and Post-Impressionism'', by Arthur Jerome Eddy | Rhomboid | Epaxial and hypaxial muscles | Color plate by Jacques Gautier d'Agoty, showing some of the muscles of the head. Part of a series of illustrations from Myologie complete en couleur et grandeur naturelle (1746) with texts by French physician and anatomist Guichard Joseph Duverney |