Brachial Plexus

About the Brachial Plexus

The brachial plexus is a network of nerves formed from the anterior rami of the fifth cervical to first thoracic spinal nerves. Its fibers combine and separate in a characteristic sequence of roots, trunks, divisions, cords, and terminal branches as they pass from the neck, beneath the clavicle, and into the axilla. The five main terminal branches are the musculocutaneous, axillary, radial, median, and ulnar nerves, which together supply movement and sensation to the shoulder, arm, forearm, and hand. Injuries can occur from stretching or tearing during motorcycle accidents and contact sports, or during difficult births, where they are known as obstetric brachial plexus palsy. Erb palsy affects the upper roots and leaves the arm hanging with the hand turned backward, sometimes called the waiter tip position, while Klumpke palsy affects the lower roots and the hand. Anesthesiologists commonly numb the plexus with nerve blocks for arm surgery.