Bilateral variant origin of pectoralis major.

ABSTRACT

The variable origin of muscles is not uncommon though the complete or partial absence of the clavicular head of pectoralis major muscle is rare. This paper deals with bilateral partial absence of clavicular head of pectoralis major muscle. The clavicular head was arising only in the middle of medial half of the clavicle and was separated from sternocostal head by a gap of 2.5cm and laterally from the origin of deltoid from clavicle by a gap of 2.5cm. Nerve supply of this muscle was from lateral and medial pectoral nerves as usual. The partial absence of the clavicular head of pectoralis major muscle becomes important in cases of reconstructive surgery as this head is required to cover the lateral acromioclavicular defect and in cases of established facial paralysis.