The vessels and nerves in the pectoacromial region were dissected under an operative microscope on 50 human specimens. The main blood supply of this region comes from the thoracoacromial artery. Its deltoid, pectoral, and clavicular branches all have secondary branches to the pectoralis major. In 94% of the cases, the .deltoid branch sends out a cutaneous branch known as the thoracoacromial cutaneous branch. Its external caliber is 1.22mm in average and it distributes over the cutaneous region covering the anterior portion of the del-toideus, the subclavian fossa, and the upper portion of the pectoralis major with an average area of 80.63cm2.An extended pectoralis major myocutaneous flap can be designed taking the thoracoacromial artery or its deltoid branch as its pedicle. This myocutaneous flap can contain an axial skin flap supplied by the thoracoacromial cutaneous branch.