Brachial Plexuses

The front branches of the lower four cervical nerves and the first thoracic nerve produce the brachial plexuses. These networks of nerve fibers are located deep within the shoulders between the neck and the axillae (armpits). The major branches emerging from the brachial plexuses include (1) "musculocutaneous nerves," which supply muscles of the arms on the front side and skin of the forearms; (2) "ulnar nerves," which supply muscles of the forearms and hands and the skin of the hands; (3) "medial nerves," which supply muscles of the forearms and muscles and skin of the hands; (4) "radial nerves," which supply muscles on the back of the arms and the skin of the forearms and hands; and (5) "axillary nerves," which supply muscles and skin of the upper, lateral, and posterior regions of the arms.