In the present study we analyzed the anatomical basis for the use of the pectoralis major muscle based on alternative pedicles in order to evaluate its clinical applications in cases of potential lesion of the internal thoracic artery. The patterns of blood supply depending on the internal thoracic artery, previously dissected for coronary by-pass surgery, were studied in both sides of five embalmed cadavers and five anterior thoracic walls taken from autopsies. The secondary vascular pedicles depending on the internal thoracic artery for the pectoralis major muscle were dissected and injected with physiological saline stained solution in the embalmed cadavers. Moreover, studies of intravascular injection by means of radio-opaque contrast and physiological saline stained solution were carried out in the anterior thoracic walls obtained from clinical autopsies. The results showed that complete injection of the pectoralis major muscle was achieved depending exclusively on the two proximal perforating branches of the two first intercostal spaces, which represented the vascular pedicle for medial transposition of the pectoralis major flap, in cases with previous dissection of the internal thoracic artery for coronary by-pass.