A Cadaveric Study of the Martin-Gruber Anastomosis Morphology

The Martin-Gruber anastomosis (MGA) is a neural communication between the median nerve (MN) and ulnar nerve (UN), typically located in the proximal forearm. Despite its clinical significance in diagnosing and treating nerve pathologies such as carpal and cubital tunnel syndromes, anatomical variations of MGA remain underexplored. This cadaveric study aimed to determine MGA prevalence, characterize its morphological patterns, and evaluate implications for peripheral nerve surgeries such as ulnar nerve transplantation and upper extremity neuropathies.

Cadaveric dissections of 101 forearms were conducted at Tilman J. Fertitta Family College of Medicine and Baylor College of Medicine. Only intact MGA specimens were included. Nerves were exposed by reflecting fascia and muscle layers, and MGA pathways were traced retrogradely. Measurements included the distance of MGA origins from the medial epicondyle (ME) and the width of the communication ramus. A custom classification system categorized MGA patterns based on anatomical configurations. The Martin-Gruber anastomosis prevalence found within the study was 37.6% (n = 38/101), with type I being the most common at 58% (n = 22/38), followed by type III at 32% (n = 12/38), and type II at 11% (n = 4/38). Unilateral MGA predominated at 53% (n = 20/38) and most patterns were intramuscularly embedded in the flexor digitorum profundus (FDP) muscle. Communication fiber lengths ranged from 3 to 10 cm from the ME. Findings corroborate prior classifications while highlighting subtle variations in morphology.

This study reveals a higher MGA prevalence compared to global averages, underscoring its clinical importance. Detailed morphological insights enhance understanding of MGA variations, aiding surgical precision, and improving outcomes in nerve repair and transplantation. Further research on MGA functional dynamics is recommended to refine classification frameworks and surgical approaches.