Innervation of the pectoralis major muscle: anatomical study

Owing to the diverse application of the pectoralis major muscle (Pmaj) in reconstructive surgery, with special reference to its safe and functional transfer, a precise knowledge of its nerve supply becomes mandatory. The aim of the present study was to investigate its innervations.

A total of 30 specimens of pectoral regions pertaining to 15 embalmed adult human cadavers, aged between 30 and 67 years (10 males, 5 females), were dissected in pursuit of this aim.

The proximal and the upper third of the distal segments of the muscle were constantly supplied by the ventral division, through medial and lateral branches, and the dorsal division of the lateral pectoral nerve, respectively. The ventral branches of either the pectoral loop (in 26/30 specimens) or the medial pectoral nerve (MPN) (4/30) penetrated the upper third of the pectoralis minor to supply the lower two-thirds of the distal segment of the Pmaj through 1 or 2 branches. Concomitantly, the dorsal branch of either the MPN (26/30) or the pectoral loop (4/30) supplied the posterior limb of its tendon. The fourth intercostal nerve participated in the inferolateral muscle supply (4/30).

The muscle is mainly innervated by the lateral pectoral nerve supplemented by the branches of the MPN. The proximal segment, having a separate nerve, allows its functional transfer. Care should be practiced whenever the distal segment is to be harvested, because of having multiple nerves.