The anatomic study of the connection between median and ulnar nerve in the forearm, were first described by the Swedish anatomist Martin, in 1763 and later by Gruber in 1840. This connection is now known as the Martin-Gruber anastomosis. Despite its long history, its nature remains unclear.

We performed anatomical dissection in 90 fresh cadaveric forearms. 49 of them were on the right forearm and 41 on the left forearm. We supplement the anatomic study with a histologic examination of the bundles in the connections. We found 9 cases with a linking branch (10%). The distance between the proximal end of the anastomosis from the medial condyle were about 6.5 cm (5.0 to 8.0). The length of the anastomotic branches was between 3.5 – 6.5 cm. All the linking branches were located in the proximal third of the forearms. No connections between ulnar – median nerve were found.

In conclusion the Martin – Gruber anastomosis is clinically important. A lesion of the median nerve situated proximal of the anastomosis would affect the median thenar muscles, whereas a lesion distal of that level would not. The anastomosis has a clinical significance for understanding median nerve lesions and the carpal tunnel syndrome. A lesion of the ulnar nerve situated proximal of the anastomosis would affect the ulnar muscles of the hand, whereas a lesion distal of that level would not. By recognizing the existence of the linking branches mistakes in the diagnosis of the peripheral nerve lesions can be avoided.

The anatomic study of the connection between median and ulnar nerve in the forearm, were first described by the Swedish anatomist Martin, in 1763 and later by Gruber in 1840. This connection is now known as the Martin-Gruder anastomosis. Despite its long history, its nature remains unclear.

We performed anatomical dissection in 60 fresh cadaveric forearms. Thirty-four of them were on the right forearm and 26 on the left forearm. We supplement the anatomic study with a histologic examination of the bundles in the connections. We found 5 cases with a linking branch (8.5%).The distance between the proximal end of the anastomosis from the medial condyle were about 6.5 cm (5.0 to 8,0). The length of the anastomotic branches was between 3.5 – 6.5 cm. All the linking branches were located in the proximal third of the forearms. No connections between ulnar – median nerve were found.

In conclusion the Martin – Gruber anastomosis is clinically important. A lesion of the median nerve situated proximal of the anastomosis would affect the median thenar muscles, whereas a lesion distal of that level would not. The anastomosis has a clinical significance for understanding median nerve lesions and the carpal tunnel syndrome. A lesion of the ulnar nerve situated proximal of the anastomosis would affect the ulnar muscles of the hand, whereas a lesion distal of that level would not. By recognizing the existence of the linking branches mistakes in the diagnosis of the peripheral nerve lesions can be avoided.