The _cutaneus brachii superior_ is a small nerve which springs from the last brachial plexus root and passes between the skin and the triceps brachii muscle on the dorsal surface of the upper arm, or brachial, region. It extends down over the elbow region, where it gives off numerous branches to the skin of these regions, to the meta-patagium and to the extensor muscles of the upper arm. The _brachialis longus superior_ is a large nerve trunk which springs from most of the other plexus roots. It extends around to the dorsal side of the upper arm and supplies the skin, the feathers, and the muscles of the forearm and the hand. Branches from this nerve trunk supply the triceps brachii and other muscles of the region. The main branch passes between the radius and the ulna, and, passing the elbow-joint, gives off branches to that joint. Passing on, it divides into two branches. One of these extends superficially over the upper part of the condylus ulnaris and supplies the extensor digitorum communis and the extensor metacarpi ulnaris, or flexor metacarpi radialis muscles, and, continuing superficially to the ulnar side, is distributed to the skin of the region. The second, a deep branch, extends on the ulnar side of the radius over the extensor indicis longus, and innervates the latter muscle, the extensor pollicis longus, the extensor pollicis brevis, the adductor pollicis, the interosseous palmaris, and the flexor digitorum. The inferior brachial plexus gives off the following branches: The _supra-coracoideus_, a large nerve which springs from the first main root of the plexus, and passes outward through the foramen coracoideum of the sternal ligament. The _sterno-coracoideus_, a small nerve which extends downward from the plexus. The somewhat large _posterior coraco-brachialis_, nerve which springs from one or two middle roots of the plexus and accompanies the pectoral nerve. The _anterior thoracic_, a large nerve which springs from two or three of the posterior roots of the plexus and extends to the shoulder cavity where it branches. The anterior branch is distributed to the patagium and the front part of the pectoral muscles. The posterior branch supplies muscles along the side of the thorax and extends into the abdominal muscles. The _anterior coraco-brachialis_, a small nerve which springs mostly from the inferior longus brachialis, passes to the distal end of the tuberculum humeralis radii, then passes backward between the front part of the humerus and the biceps, where it supplies the anterior coraco-brachialis. The _cutaneous brachialis_ et _inferior brachialis_, a small nerve which springs from the posterior roots of the plexus. It is distributed to the skin of the region and branches are given off to the patagii and the ventral wing surface. A few branches extend as far as the upper arm.