Anatomic evaluation of the subcoracoid pectoralis major transfer in human cadavers

Subcoracoid transfer of the pectoralis major has recently been described as a reconstruction for subscapularis insufficiency. The purpose of this stud y was to examine the surgically relevant anatomy of this transfer. The impo rtance of understanding this anatomy was recently highlighted to us followi ng our encounter with musculocutaneous neuropraxia in 2 patients after tran sfer of the entire pectoralis major, one deep to the musculocutaneous nerve . Dissections were performed on 20 fresh, whole human cadavers in which the entire pectoralis major muscle, medial and lateral pectoral nerves, and mu sculo-cutaneous nerve were explored and quantified. The relationship betwee n the pectoralis major and the conjoined tendon was studied in situ and aft er simulated transfers. The medial and lateral pectoral nerves were located far medial to the pectoralis major tendon insertion and appeared to be saf e from injury as long as surgical dissection remained lateral to the pector is minor and less than 8.5 cm from the humeral insertion. Transfer of the p ectoralis major superficial to the musculocutaneous nerve created less tens ion than transfer deep to the musculocutaneous nerve. Because proximal inne rvation of the coracobrachialis and short head of the biceps is not an unco mmon occurrence, a split pectoralis major transfer, release of the proximal musculocutaneous branches, or debulking, of the pectoralis major muscle be lly may be required in some instances to prevent tension on the nerve. Beca use of the variability and location of the musculocutaneous nerve, it shoul d always be visualized operatively. Transfer of the pectoralis major tendon lateral to the biceps tendon appeared to best restore the muscle length-te nsion relationship.