Unusual concurrence of intermediate pectoralis muscle and variant insertion of pectoralis minor with its clinical aspects.

Vani PC, Anbalagan J, Rajasekar SS

Pectoralis minor is a triangular muscle situated in upper chest deep to pectoralis major. Intermediate pectoralis muscle is an accessory muscle that intervenes between pectoralis major and minor. We report a rare case of bilateral variant insertion of pectoralis minor associated with intermediate pectoralis muscle in a female cadaver. On right side the origin of intermediate pectoralis muscle was from 4^th rib, 5^th rib and external oblique aponeurosis. The right pectoralis minor originated from 3^rd to 5^th ribs. Both intermediate pectoralis muscle and pectoralis minor inserted onto coracoid process as well as capsule of the glenohumeral joint. On the left side the intermediate pectoralis muscle originated from 6^th rib, external oblique aponeurosis, fascia over rectus sheath. The pectoralis minor originated from 2^nd to 5^th ribs. Both inserted onto the fascia over coracobrachialis. The knowledge of these variants is important to clinicians in procedures involving pectoral and axillary region.