Abstract
The authors describe a rare unilateral muscle variation in the thoracic wall combining the pectoralis quartus and chondro-epitrochlearis muscles. A routine dissection was performed in the upper right limb of a male adult cadaver with approximately 35-50 years of age, embalmed in formalin 10%. An accessory muscle, the pectoralis quartus, was identified and was associated with a tendon that was inserted in the medial humeral epicondyle, characteristic of the chondro-epitrochlearis muscle tendon. Such variations have significant clinical relevance to orthopedics, mastology, neural and vascular surgery, and other specialties, for surgical approaches in both the axillary and brachial regions.