C5 and C6 nerves innervate the muscles of the shoulder and the elbow. The patients who has involvement of C5 and C6 will have pain over a shoulder and the upper arm and going up to the outer side of the forearm and the thumb. These patients may have tingling and numbness of the same area and may have weakness in the shoulder and the elbow presenting in the form of elevating the shoulder and bending the elbow.