Costodorsalis ­ an Additional Slip of Pectoralis Major Muscle: a Case Report

Occurrence of variant muscular slips from pectoralis major muscle is rare. In this report, we present a rare case of aberrant muscular slip associated with the pectoralis major muscle which we call costodorsalis. This muscular slip originated from the 6th rib near the costochondral junction and ran along the lower border of pectoralis major muscle. It crossed the axilla from medial to lateral side and merged with the latissimus dorsi muscle. This type of origin and insertion is unique and has not been reported earlier. The knowledge of this muscle variation may be of special importance to the anesthesiologists, physiotherapists and plastic surgeons.