Anatomical Study of Pronator Teres Muscle Innervation and Clinical Significance in Nerve Transfer

Abstract

The anatomical relationship of the median nerve and its innervation pattern are variable and may have direct implications in surgical procedures such as distal nerve transfers. The objective of this study was to evaluate the anatomical variations of pronator teres muscle (PTM) innervation and its clinical significance in nerve transfers. Data were collected regarding the number of median nerve branches, site of their origin, contribution with branches of other muscles and the possibility of transferring expendable branches of PTM to the anterior interosseous nerve (AIN) and radial nerve. The most common origin of the branches was proximal to the humeral intercondylar line. The presence of only one PTM branch was identified in 9 limbs, in which 6 was exclusive for this muscle. The majority of specimens presented more than one branch to the PTM, with two branches in 19, although only 6 of these did not share branches with other muscles. The proximal branch of the PTM was long enough to be transferred to the AIN in 23 limbs and branches of the radial nerve in all. These transfers were possible even during the forearm prone-supination and flexion-extension of the elbow. The use of the PTM branch may be considered for transfers in C7-T1 root injuries of the brachial plexus, with care regarding the availability of multiple PTM branches and tension to the AIN and radial nerve branches.