The radial nerve runs all the way down the arm. It not only controls movement of the tricep muscles, it also controls wrist extention and assists with sensation in the hand and wrist. The triceps are located on the back of the arms. Any problems with hand, wrist, or tricep movement and any arm sensation problems indicate possible radial nerve dysfunction. This comes from prolonged nerve pressure, nerve compression, or direct trauma. Examples of possible causes include consistently wearing a tight fitting watch, a humerus fracture, sleeping in positions that put pressure on the upper arm, or using crutches improperly. If the damage only affects one nerve group, like the radial nerve, it is called mono-neuropathy. The radial nerve passes through the humerus spiral groove and the arch formed by the attachment of the humerus and triceps. It also passes through the lateral intermuscular septum and the Arcade of Frohse. This is located below the elbow but above the supinator.