LUMBRICALES MUSCLE AND SURGERY OF INJURIES OF THE EXTENSOR APPARATUS OF FINGERS

The tendons of the extensors and flexors of all fingers of the hand are in known functional reciprocal relationships provided by the structures of the cortical representation of the hand; lumbricales muscle acts as a balance between the deep flexor of the finger, providing flexion of the distal interphalangeal joint of the II-V fingers and the extensor of the finger, extending successively the finger in the proximal and distal interphalangeal joints. According to modern concepts, the ends of the injured extensor tendon of the finger in zone I approach each other when the distal phalanx is unbent, and preferably in the distal position, in the distal interphalangeal joint. This approach does not take into account the fact that in the unfolded position of the finger, the proximal border of the dorsal aponeurosis is contracted upwards by contraction of the abdomen of the corresponding muscle, contributing to an increase in diastasis between the ends of the injured tendon. Taking into account the anatomical, physiological, and clinical data obtained by us, a change in the treatment paradigm is necessary in terms of approaching the ends and postoperative immobilization because it is necessary to reduce the tension of the lateral beams of the dorsal aponeurosis, which form the extensor tendon in zone I. This can be achieved by physiological rest of the wormlike muscles: flexion by 58-60° in the metacarpophalangeal joint, 36-38° in the proximal interphalangeal joint, and 0° in the distal.

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