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

Vani PC, Anbalagan J, Rajaseka

Abstract

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 4th rib, 5th rib and external oblique aponeurosis. The right pectoralis minor originated from 3rd to 5th 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 6th rib, external oblique aponeurosis, fascia over rectus sheath. The pectoralis minor originated from 2nd to 5th ribs. Both inserted onto the fascia over coracobrachialis. The knowledge of these variants is important to clinicians in procedures involving pectoral and axillary region.