The brachial plexus refers to a network of nerves that start out in the neck and move through the upper limbs. This covers the shoulders, arms, elbows, forearms, wrist as well as the hand. All five of the nerves originate in the spinal cord. These nerves are responsible for the sensations and motor movements of the upper extremity. In medical terms, the brachial plexus is the somatic nerve plexus between the ventral rami of the lower four cervical and first thoracic nerve.