A case of coexistence of three anatomical variations in the forearm: Gantzer's muscles, Martin-Gruber anastomosis, and nerve of Henle

During routine dissection of a left forearm, a simultaneous occurrence of Gantzers' muscles, Martin-Gruber anastomosis and nerve of Henle was observed in a 72 year old male. Both accessory muscle heads (Gantzers' muscles) originated from the medial epicondyle and coursed distally. The lateral accessory head crossed the ulnar artery, the Martin-Gruber anastomosis, and the branches of the median nerve to the flexors, the interosseous neurovascular bundle and the median nerve itself. The medial accessory head (Flexor Digitorum Profundus Accessorius) crossed the above structures except the last two. The Martin-Gruber anastomosis was a connection between the nerve to the Flexor Digitorum Profundus (a branch of the median nerve) and the ulnar nerve, which traversed posterior to the ulnar artery and two accessory muscle heads. The nerve of Henle originated from the ulnar nerve just proximal to joining the Martin-Gruber anastomosis, coursed distally with the ulnar artery, and supplied the skin of the distal forearm. These muscular and nervous anomalies are clinically significant since they are mutually related to one another and could compress the nerves or may be compromised during surgical procedures.