Anomalous pectoral musculature.

Anomalous disposition of pectoral muscles was encountered in an adult female cadaver on the left side. A prominent cleft separating the sternocostal and clavicular portions of the pectoralis major was noticed. The fibers of pectoralis major were partially fused with the deltoid, resulting in obliteration of the deltopectoral groove. Interestingly, cephalic vein was seen traversing superficial to the clavicular portion of the pectoralis major and pierced it to drain into the axillary vein. The pectoralis minor was inserted mainly on the coracoid process and few fibers were found blending with the coracobrachialis and short head of biceps brachii. Further, pectoralis minimus, a rare anatomic variant, was also observed lying superior to pectoralis minor. It was innervated by a twig from the lateral pectoral nerve at its superficial surface. Awareness of possibility of such anomalous muscles is important for surgeons operating on the chest wall.