Martin-Gruber Anastomosis

The Martin-Gruber Anastomosis (or Martin-Gruber Connection) is a communicating nerve branch between the median nerve and the ulnar nerve in the forearm. It is the most common anastomotic anomaly that occurs between these two nerves. This connection carries motor nerve fibers. In cases of nerve lesions of the median or ulnar nerves the MGA can serve as a conduit for alternative innervation of portions of the forearm or hand. This inconstant pattern of connection can serve as explanation for a difficult or challenging differential diagnosis. In one study, the MGA was found in 22.9% of cadaver specimens. This relatively high incidence demonstrates the necessity for healthcare specialists to factor the MGA into their diagnoses.