The brachial plexus (BRAY-key-el PLEK-sis) is a system of nerves that provides movement and sensitivity to the shoulder, arm and hand. The nerves supporting the arm exit the spinal pilaster high in the neck; those that support the hand and fingers exit lower in the neckline.
This nerve complex is collected of four cervical nerve roots (C5-C8) and the first thoracic courage root (T1). These roots syndicate to form three trunks. C5-C6 form the upper trunk, C7 continues as the central trunk and C8-T1 form the lower stem.
Each trunk splits into a separation. Half the divisions globally source flexor muscles (that lift and bend the arm). The others supply the extensor muscles (that uncurl the arm and bring it down).