Spinal nerve root C8 innervates both proximal and distal muscles. Distally, C8 fibers form the median, ulnar, and radial nerves. These muslces are: Latissimus dorsi, Pectoralis major, Triceps, Palmaris longus, Flexor digitorum superficialis, Flexor policis longus, abductor policis longus, Extensor policis brevis, Extensor policis longus, Extensor carpi ulnaris, Flexor carpi ulnaris, Flexor digitorum profundus, Lumbricals, and Interossei.