Inervación del músculo flexor superficial de los dedos

Innervation of the flexor digitorum superficialis muscle (FDS) is controversial. Several authors describe that the branches of this muscle arise independently or from a common trunk that comes from the median nerve, within the ulnar region. Other descriptions indicate the presence of additional branches in the middle and distal third of the forearm. These differences are also reflected when describing the motor points. The aim was to determine the number, location and distribution patterns of the branches for the FDS. 30 forearms of Brazilian adults were used. About the number of branches, 26 % presented a single branch (R1). 57 % presented two branches (R1 and R2) and 17 % presented 3 branches (R1, R2 and R3). Regarding the format of origin, 87 % of the R1 emerged independently, while 13 % emerged from a common trunk. In the case of R2 and R3, 100 % emerged independently. About the points of origin, 90 % of the R1 were originated in the proximal third of the forearm, while 60 % of the R2 emerged from the middle third, and of the 5 R3, 60 % were originated in the middle third and the remaining two emerged in the distal third. This same variability was present in the motor points distribution. Regarding the distribution patterns of these motor branches, two types were identified. Pattern I was present in 85 % and was characterized by all branches arising at a point distal to the origin of the anterior interosseous nerve (AIN), however, in the type II pattern (15 % of the sample), the first branch was originated proximal to the origin of the AIN.