The Muscular Branching Patterns of the Ulnar Nerve to the Flexor Carpi Ulnaris and Flexor Digitorum Profundus Muscles

Abstract

The branching pattern of the ulnar nerve in the forearm is of great importance in anterior transposition of the ulnar nerve for decompression after neuropathy of cubital tunnel syndrom and malformations resulting from distal end fractures of the humerus. In this study, 37 formalin-fixed forearms were used to demonstrate the muscular branching patterns from the main ulnar nerve to the flexor carpi ulnaris muscle (FCU) and ulnar part of the flexor digitorum profundus muscle (FDP). Eight branching patterns were found and classified into four groups according to the number of the muscular branches leaving the main ulnar nerve. Two (Group I) and three (Group II) branches left the main ulnar nerve in 18 and 17 forearms respectively. The remaining two specimens had four (Group III) and five (Group IV) branches each. Usually one or two branches were associated with the innervation of the FCU. However, in 2 cases, three and in one, four branches to FCU were observed. The FDP received a single branch in all cases, except in four, all of which had two branches. In six forearms, a common trunk was observed arising from the ulnar nerve to supply the FCU and FDP. The distribution of the muscular branches to the revealed muscles was outlined in figures and the distance of the origin of these branches from the interepicondylar line was measured in millimeters. The first muscular branch leaving the main ulnar nerve was the FCU-branch in all specimens. The terminal muscular branch of the ulnar nerve to the forearm muscles arose at the proximal 1/3 of the forearm in all specimens. In 7 forearms, Martin-Gruber anastomosis in form of median to ulnar was observed.

Median and ulnar nerve anastomoses in the upper limb: A meta‐analysis

“…The MGA is the most widely discussed and studied of the 4 types of anastomoses. In our study the pooled prevalence of MGA was 19.5%, similar to the anatomical study by Marur et al 24 who reported a prevalence of 18.9%. Subgroup analysis according to type of study revealed that electrophysiological studies had a higher pooled prevalence of 23.5% when compared with the 16.4% in cadaver studies.…”

“…A total of 6 studies ( n = 67 upper limbs) reported data on the position of the MGA with respect to the ulnar artery . In a majority of cases, the connection between the nerves was located posterior to the ulnar artery (89.8%, 95% CI, 74.9%–99.0%) rather than anterior (10.2%, 95% CI, 0.1%–25.1%; Cochran Q, P = 0.03; I‐squared = 58.7%, 95% CI, 0.0%–83.3%).…”

“…The characteristics of included studies are summarized in Supplementary Tables S1-S4 (available online), which include the prevalence of anastomoses in upper limbs as reported by the individual studies. A total of 41 studies (n 5 6,409 upper limbs) reported data on MGA, [2][3][4][6][7][8]11,13,22,24,[26][27][28][29][30][31][32][33]38,39,[42][43][44][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77] 12 studies (n 5 1,884 upper limbs) reported data on MA, 2,4,11,29,30,38,39,44,45,47,…”

“…A total of 41 studies (n 5 6,409 upper limbs) reported the prevalence of MGA. [2][3][4][6][7][8]11,13,22,24,[26][27][28][29][30][31][32][33]38,39,[42][43][44][62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77] The overall pooled prevalence of MGA was 19.5% (95% CI, 16.2%-23.1%; Cochran Q, P < 0.001; I-squared 5 91.2%, 95% CI, 89.0%-93.0%) ( Table 1; Fig. 5A).…”

“…Further analysis of the types of MGA was performed on 17 studies (n 5 300 upper limbs). 2,3,8,13,24,25,[28][29][30][31][32][33]38,68,69,75,76 In most cases, the CB was found between the AIN and the UN (type 2) with a pooled prevalence of 57.6% (95% CI, 40.4%-67.5%). More detailed prevalence data regarding the types of MGA are listed in Table 2.…”