Clinical repercussions of Martin-Gruber anastomosis: anatomical study

Abstract

ObjectiveThe main objective of this study was to describe Martin-Gruber anastomosis anatomically and to recognize its clinical repercussions.Method100 forearms of 50 adult cadavers were dissected in an anatomy laboratory. The dissection was performed by means of a midline incision along the entire forearm and the lower third of the upper arm. Two flaps including skin and subcutaneous tissue were folded back on the radial and ulnar sides, respectively.ResultsNerve communication between the median and ulnar nerves in the forearm (Martin-Gruber anastomosis) was found in 27 forearms. The anastomosis was classified into six types: type I: anastomosis between the anterior interosseous nerve and the ulnar nerve (n = 9); type II: anastomosis between the anterior interosseous nerve and the ulnar nerve at two points (double anastomosis) (n = 2); type III: anastomosis between the median nerve and the ulnar nerve (n = 4); type IV: anastomosis between branches of the median nerve and ulnar nerve heading toward the flexor digitorum profundus muscle of the fingers; these fascicles form a loop with distal convexity (n = 5); type V: intramuscular anastomosis (n = 5); and type VI: anastomosis between a branch of the median nerve to the flexor digitorum superficialis muscle and the ulnar nerve (n = 2).ConclusionKnowledge of the anatomical variations relating to the innervation of the hand has great importance, especially with regard to physical examination, diagnosis, prognosis and surgical treatment. If these variations are not given due regard, errors and other consequences will be inevitable.

A comprehensive review of motor innervation of the hand: variations and clinical significance

“…The MGA is formed in the forearm by an anastomosis between either the Anterior Interosseous Nerve or the main body of the Median nerve, to the Ulnar nerve [12,13,26,45,53,70]. The nerve axons start in the proximal Median nerve and cross the forearm to join the distal Ulnar nerve [70].…”

Comprehensive Summary of Anastomoses between the Median and Ulnar Nerves in the Forearm and Hand

“…5,23,25,26 Conversely, a patient may present with symptoms of carpal tunnel syndrome, but show negative findings with regard to Tinel and Phalen tests, due to ulnar nerve compression at the elbow. 8 The intramuscular MGA subtype mentioned previously, found in 5% of total limbs (n = 100) in the study by Caetano et al, 8,19 is clinically relevant in and of itself. This branch penetrates the flexor digitorum profundus muscle, potentially serving as a location of nerve compression.…”

“…7,9,[15][16][17][18] Thirty-three percent of specimens with MGA present demonstrated this organization (type I) in Cavalheiro et al Other possible arrangements described in the same study included double anastomosis between the anterior interosseous nerve and ulnar nerve (type II, 7.4%); anastomosis between the median and ulnar nerves (type III, 14.8%); anastomosis between branches of the median nerve and ulnar nerve heading toward the flexor digitorum profundus muscle of the fingers (type IV, 18.5%); intramuscular anastomosis (type V, 18.5%); and anastomosis between a branch of the median nerve to the flexor digitorum superficialis muscle and the ulnar nerve (type VI, 7.4%). 19 While MGA is most frequently associated with the ulnar artery, it is important to note that it has also been related to the anterior ulnar recurrent artery. Awareness of this variation during open reduction and internal fixation of a radius/ulnar shaft fracture may be significant in minimizing iatrogenic damage.…”

An Anatomical Study of Median and Ulnar Nerve Communication in the Forearm

“…In our study both the cases presented a Pattern I b type of anastomosis. Cavalheiro et al [22] classified the anastomosis into six types based on cadaveric study of 100 forearms : type I: anastomosis between the anterior interosseous branch of median nerve and the ulnar nerve ; type II: anastomosis between the anterior interosseous branch of median nerve and the ulnar nerve by two branc hes (double anastomosis); type III: anastomosis between the median nerve and the ulnar nerve; type IV: anastomosis between branches of the median nerve ( destined for the flexor muscle bulk and function was preserved [26]. Brandsma et al described two clinical cases, with complete rupture of the ulnar nerve at the elbow and median nerve injury in the wrist, secondary to leprosy neuropathy.…”