Various surgical procedures require surgeons to have detailed knowledge of the course of blood vessels in the masseter muscle, such as masseter muscle flap formation, mandibular angle resection, parotidectomy, and mandibular ramus osteotomy. Without this knowledge serious complications can occur, endangering the lives of patients. Occasionally, during routine dissections we sometimes encounter an additional branch. The purpose of this study was to provide a comprehensive detailed anatomic description of the blood supply of the masseter muscle. This will provide critical information for various surgical procedures. Twenty-five Korean cadavers were dissected and subjected to modified Sihler's method to reveal the branching patterns of the arteries surrounding the masseter muscle, and its intramuscular blood supply. The masseter can be supplied by seven branches from the external carotid artery. Among these, the masseteric branch from the deep temporal artery has not been described previously. This previously undescribed branch enters the medial surface of the masseter, turning medially around the anterior border of the ramus immediately after the branching point of the deep temporal artery. The branch originating from the transverse facial artery was the largest, and the branches originating from the external carotid artery and deep temporal artery were the smallest. Examination of intramuscular patterns revealed that the branches of the transverse facial artery were the most widely distributed. When considering arterial diameters and distribution areas, the branches of the transverse facial artery can be considered the main components of the seven branches supplying the masseter muscle.