Langer's arch is identified in up to 7% of axillary explorations; in a three-month period we identified three individuals among forty-six patients undergoing axillary surgery with this abnormality. Langer's arch is a muscular-tendinous structure that usually extends from latissimus dorsi to pectoralis major muscle. The purpose of this article is to describe the embryological derivation of this muscular variant from the panniculus carnosus and to define its anatomical features. The clinical implications both symptomatically and as an unexpected finding during axillary dissection, are also discussed.