Microsurgical anatomy of branches of musculocutaneous nerve: clinical relevance for spastic elbow surgery

Abstract

The neurotomy of musculocutaneous nerve is a treatment for patients who suffer from spastic elbow flexion when medical and reeducative treatments have failed. It consists in sectioning motor branches of musculocutaneous nerve which are destined to the biceps brachii and brachialis muscles, both being the main elbow flexor muscles. The aim of this study was to analyse the distance, where each motor branch arises from the musculocutaneous nerve to both biceps brachii and brachialis muscles, to establish precisely the localisation and length of the necessary incision to reach its branches for surgery. Eighteen musculocutaneous nerves from ten cadavers were dissected. None of them reported with a previous pathology. The cadavers were laid on the back with 30-35° of abduction, a complete extension, and supination of the upper limb. The localization of motor branches was to be found in the middle third of the upper arm, with an average from the base of the humeral major tubercle of 11.46, 12.40, and 12.87cm for the biceps brachii and 16.36, 19.10, and 16.88cm for the brachialis muscle. The incision needed to reach the motor branches of the musculocutaneous nerve should be localised between 10 and 20cm from the major humeral tubercle and may be shorter than usual.