Although spinal nerve root C5 forms part of the radial nerve, none of the fibers from C5 innervate any hand muscles. Rather it innervates more proximal muscles that support hand function. The muscles innervated by C5 are: Serratus Anterior, Deltoid, Ifraspinatus, Teres minor, Teres major, Pectoralis major, Supraspinatus, Biceps, Brachialis, Brachioradialis, Supinator.