June 20, 2024

Martin Gruber anastomosis is the connection between the median nerve and ulnar nerve in the forearm which normally are not connected.

In most of cases Anterior interosseous nerve (AIN) is connected to the ulnar nerve in the forearm.

Margin Gruber anastomosis
Margin Gruber anastomosis

The clinical picture of the patient with nerve injury will present as an atypical presentation to other patients.

A median nerve lesion above communicating branch will affect the median nerve muscles of the hand but a lesion below anastomosis will not affect the median nerve and spare thenar motor intrinsic muscles of the hand which is supplied by the median nerve.

However, the ulnar nerve lesion above communicating area produces an unusual pattern of intrinsic muscle paralysis.

Lesion to the ulnar nerve at the wrist will cause a severe deficit of hand function which is greater than expected

Incidence of Martin Gruber anastomosis

Around 15%

Classifications of Martin Gruber anastomosis

Type ICommunication occurs from AIN to the Ulnar nerve
Type IICommunication occurs from the median nerve before division to the Ulnar nerve
Type IIICommunicating branches from median/AIN and ulnar nerve form a common branch
Type IVCommunication occurs from AIN/ Median nerve to Ulnar nerve as a bifurcation in ulnar nerve
Classification of MGA
Classification of MGA

Other Important anastomosis:

Marinacci anastomosis

Ulnar to median anastomosis (reverse MGA)

Riche-cannieu anastomosis

Anastomosis between the deep branch of the ulnar to a recurrent branch of the median nerve

Berrettini Anastomosis

Anastomosis between communicating between the digital nerve (sensory nerves) arising from the ulnar and median nerve in the hand

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