Anatomical variations in the axillary region do not always appear in modern human anatomy texts, which leaves the risk of diagnostic and surgical errors by doctors unaware of these variations. This work presents an anatomical variation of muscular type in the axillary region that can potentially generate clinical manifestations or iatrogenic results during surgical procedures. Routine dissection of an upper limb in a male cadaver. An atypical muscle was found in the axillary region, located at the base of the right axilla, and conformed by three muscle fascicles that give rise to a common muscular belly. The three fascicles are joined at the base of the axilla, and form a thin flat muscle 120 mm long from this join to its tendon, with a cross-section diameter of 15 mm and a thickness of 2 mm. The common belly of the muscle establishes a posterior relationship with the neurovascular elements of the axillary fossa and partially covers them. The tendon 150 mm in length originates at the level of the union of the upper and middle thirds of the arm and ends inserted in the medial epicondyle of the humerus, relating in its path with muscular and neurovascular elements of the arm. Being familiar with this variation enriches diagnostic and surgical abilities and reduces the possibility of iatrogenia in surgery of the axillary and brachial regions.
KEY WORDS: Dorsoepicondylar medial muscle; Anatomical variation; Clinical anatomy.