Long Flexors of the Forearm and Hand: An Incidence of a Variation in the Pattern of Separation of Their Tendons

Long flexors of the forearm are divided to deep and superficial groups. Superficial muscles are flexor carpi radialis, flexor carpi ulnaris, flexor digitorum superficialis and palmaris longus. Deep flexors are flexor policis longus and flexor digitorum profundus. The flexor digitorum profundus is a muscle belonging to the deep flexors of the forearm forming most of the muscular bulk on the flexor aspect of the forearm. The normal pattern of separation of the four tendons of the profundus muscle is for the tendon for the index finger to separate out distinctly in the distal forearm prior to entering the carpal tunnel while the tendons for the middle, ring and little fingers separate out in the palm. In the variants presented in this study it was evident that the profundus tendon to the middle finger separated out within the carpal tunnel. This is thus a variation from the normal pattern of separation of the deep flexor tendons of the hand suggesting a possible evolutionary trend in affording greater independence of movements of fingers which is probably an adaptation to better prehensile movements of the human hand.