Anatomical Study of the Branch of the Palmaris Longus Muscle for its Transfer to the Posterior Interosseous Nerve

The objective of the study was to evaluate the anatomical characteristics and variations of the palmaris longus nerve branch and define the feasibility of transferring this branch to the posterior interosseous nerve without tension. Thirty aims from 15 adult male cadavers were dissected after preparation with 20 % glycerin and formaldehyde intra-arterial injection. The palmaris longus muscle (PL) received exclusive innervation of the median nerve in all limbs. In most it was the second muscle of the forearm to be innervated by the median nerve. In 5 limbs the PL muscle was absent. In 5 limbs we identified a branch without sharing branches with other muscles. In 4 limbs it shared origin with the pronator teres (PL), in 8 with the flexor carpi radialis (FCR), in 2 with flexor digitorum superficialis (FDS), in 4 shared branches for the PT and FCR and in two with PT, FCR, FDS. The mean length was (4.0 +/- 1.2) and the thickness (1.4 +/- 0.6). We investigated whether the branch for PL was long enough to be transferred to the posterior interosseous nerve (PIN). The branch diameter for PL corresponds to 46 % of the PIN. The PL muscle branch presented great variability. The PL branch could be transferred to the PIN proximally to the Froshe arcade without tension in all specimens even with full range of motion of the forearm. In 13 limbs was possible the tensionless transfer to PIN distal to the branches of the supinator muscle.