The serratus magnus muscle is closely attached to the upper outer anterior part of the thorax, 1899. From 'The Treatise of the Human Anatomy and Its Applications to the Practice of Medicine and Surgery, Volume I' (1899). It arises by nine fleshy digitations from the upper eight ribs and the corresponding interspaces, two digitations arising from the second rib. It draws the scapula and entire shoulder forward, thus increasing the forward reach of the arm and antatgonizing the rhomboidei muscles and central fibers of the trapezius muscle. (Photo by VintageMedStock/Getty Images)
