Absence of the musculocutaneous nerve: a rare anatomical variation with possible clinical-surgical implications.
BACKGROUND
The musculocutaneous nerve is one of the terminal branches of the lateral fasciculus of the brachial plexus, and is responsible for innervation of the flexor musculature of the elbow and for skin sensitivity on the lateral surface of the forearm. Its absence has been described previously, but its real prevalence is unknown.


METHODS
A case of absence of the musculocutaneous nerve that was observed during the dissection of the right arm of a male cadaver is described. The area of innervation was supplied by the median nerve. From this, three branches emerged: one to the coracobrachialis muscle, another to the biceps brachii muscle and the third to the brachialis muscle. This last branch continued as a lateral antebrachial cutaneous nerve. This is an anatomical variation that has clinical-surgical implications, considering that injury to the median nerve in this case would have caused unexpected paralysis of the flexor musculature of the elbow and hypoesthesia of the lateral surface of the forearm.
Fregnani
José Humberto Tavares Guerreiro
JH
Department of Morphology, Faculdade de Ciências Médicas, Santa Casa de São Paulo, São Paulo, Brazil. mdfregnani@terra.com.br
Macéa
Maria Inez Marcondes
MI
Pereira
Celina Siqueira Barbosa
CS
Barros
Mirna Duarte
MD
Macéa
José Rafael
JR
D001917:Brachial Plexus / Q000002:abnormalities; D002102:Cadaver; D005542:Forearm / Q000294:innervation*; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000002:abnormalities*; D009138:Musculocutaneous Nerve / Q000002:abnormalities*; D010243:Paralysis