Anatomical variation of the biceps brachii and brachialis muscles inervation

Introduction. A number of variations in the course and distribution of the brachial plexus and it's branches have been reported. Material and methods. We performed anatomical dissection of the right upper limb of the male cadaver, for educational purposes. Results. On this specimen the musculocutaneous nerve was not found. The radial nerve has its regular position - arises from the posterior cord of the brachial plexus and descends, accompanied by the arteria profunda brachii across the posterior surface of the humerus, between the lateral and medial head of the triceps brachii muscle. One branch of the radial nerve arises at the lower border of the pectoralis major muscle (upper third of the upper arm) and ends in biceps brachii and brachialis muscles. Other anatomical relations are regular. Conclusion. It is traditionally described that a lateral muscular branches of the radial nerve supply the lateral part of the brachialis muscle, while the musculocutaneous nerve supplies the greater part of the brachialis muscle. Also, the musculocutaneous nerve may be doubled, unusually short, or absent. Our finding is interesting because the musculocutaneous nerve is absent, and all of the upperarm muscles (antagonistic muscle groups) are innervated by the same, radial nerve.