A new era in head and neck reconstruction has been opened with the use of myocutaneous flaps. The pectoralis major myocutaneous flap is considered the most reliable of its kind but flap failures still occur secondary to tension and infection. Our standard procedure has been to follow the acromioxiphoid line as a guide to the location of the blood supply of the pectoralis major muscle. We have noticed in the operating room and during cadaver dissection that the vascular supply is sometimes more laterally located than usually described. A review of the vascular supply of this anatomic area using angiographic studies of the subclavian and its branches is presented, with important findings critical to the surgical technique used to protect the flap's blood supply.