Fractures of the forearm in an adult may involve the ulna, the radius, or both, or one may be fractured and the other dislocated. Because the ulna and the radius are joined by the interosseous membrane, injury to one often also affects the other. In the same way, the humerus can be effected from injuries of pressure at the site of the elbow. It is always wise to x-ray the entire upper extremity in most upper-limb injuries. Whatever the injury is, the patient will be incapacitated for several months by loosing the use of his or her upper extremity.