When a nerve root leaves the spinal cord and the cervical spine, it travels down into the arm. Along the way, each nerve supplies sensation (feeling) to a part of the skin of the shoulder and arm and supplies electrical signals to certain muscles to move part of the arm or hand. When a nerve is irritated or pinched - by either a bone spur or part of the intervertebral disc - it causes the nerve not work properly. This shows up as: weakness in the muscles the nerve goes to, numbness in the skin where the nerve goes, or pain in the area where the nerve travels. This condition is called cervical radiculopathy.