Topographic features of the recurrent motor branch of the median nerve in relation to the restoration of the active opposition of the thumb with proximal injuries of the median nerve

The high demands presented for a hand, as one of the most difficult segments in the anatomical, surgical and functional aspects, are due to a wide range of tasks performed daily by a person with the hand and fingers. The accuracy of manipulations with small-sized objects is due to the ability of a person to oppose the I finger to all three-phalange fingers. The loss of this movement due to injuries of the motor branches to the muscles of the elevation of the first finger leads to significant functional losses up to professional unsuitability. In relation to substantiating the possibility of peripheral nerve restoration by their end-to-side connection, a comprehensive applied anatomical and special X-ray examination was performed on 29 weakly fixed upper limbs of corpses in order to study the features of the topography of the motor branch of the median nerve to the muscles of elevation of the first finger. In the composition of the median nerve, at the level of the lower third of the forearm and wrist channel, the perineural cases forming the return motor branch to the muscles of the elevation of the first finger occupy the most lateral position. After moving away from the main trunk, the motor branch bends around the lower edge of the transverse ligament of the wrist and goes to the innervated muscles from the bottom up, from the inside out and from back to front, forming a bend. The muscular gates of the motor branch are determined at the level of the proximal third of the II metacarpal bone with a distance of 3,83±1,19 and 4,19±1,43 cm, respectively, from the distal folds of the wrist and the line connecting the styloid processes of the radius and ulna. Between the distance of the entrance gate of the motor branch of the median nerve and the length of the hand, a pronounced positive correlation is determined. The interval within which the muscular gates of the motor branch of the median nerve are located relative to the distal fold of the wrist exceeds the range of the sum of the diameters of the II and III fingers. This circumstance indicates the probable location of the motor branch and beyond the «forbidden zone» of the hand, determined by blocking it with the II and III fingers below the distal fold of the wrist. The presented data characterize the features of the topography of the distal branches and the intra-trunk structure of the median nerve. The potential possibility of selective mobilization of motor branches at the level of the distal forearm and hand for performing reconstructive interventions aimed at restoring the innervation of the muscles of the elevation of the first finger is demonstrated.