Anatomical Study of Innervation of the Supinator Muscle to Reinnervate the Posterior Interosseous Nerve.

The purpose of this anatomical study was to analyze the possibility of transferring radial nerve branches to the supinator muscle to reinnervate the posterior interosseous nerve (PIN) originating from the C7-T1 roots.  Thirty members of 15 cadavers, all male, prepared with an intra-arterial glycerol and formaldehyde solution injection, were dissected.  All dissected limbs presented at least one branch intended for the superficial and the deep heads of the supinator muscle. These branches originated from the PIN. A branch to the supinator muscle, proximal to the arcade of Frohse, was identified in six members. In addition, 2 and 3 branches to the supinator muscle were found in 11 and 4 members, respectively. In two limbs, only one branch detached from the PIN, but it duplicated itself proximal to the arcade of Frohse. Seven limbs had no branches to the supinator muscle at the region proximal to the arcade of Frohse. The branches destined for the supinator muscle were sectioned at the neuromuscular junction for connection with no tension to the PIN. The combined diameter of the branches for the supinator muscle corresponded, on average, to 53.5% of the PIN diameter.  The radial nerve branches intended for the supinator muscle can be transferred, with no tension, directly to the PIN to restore thumb and finger extension in patients with C7-T1 brachial plexus lesions.