Wrist drop
Wrist drop is a medical condition in which the wrist and the fingers cannot extend at the metacarpophalangeal joints. The wrist remains partially flexed due to an opposing action of flexor muscles of the forearm. As a result, the extensor muscles in the posterior compartment remain paralyzed. Forearm anatomy. The forearm is the part of the body that extends from the elbow to the wrist and is not to be confused with the arm, which extends from the shoulder to the elbow. The extensor muscles in the forearm are the extensor carpi ulnaris, extensor digiti minimi, extensor  digitorum, extensor indicis, extensor carpi radialis brevis, and extensor carpi radialis longus. These extensor muscles are supplied by the posterior interosseous nerve, a branch of the radial nerve. Other muscles in the forearm that are innervated by this nerve are the supinator, extensor pollicis brevis, extensor pollicis longus and abductor pollicis longus. All of these muscles are situated in the posterior half of the forearm (posterior is when it is in its standard anatomical position). Also, the brachioradialis, anconeus, triceps brachii and extensor carpi radialis longus are all innervated by muscular branches of the radial nerve in the arm. Causes . Wrist extension is achieved by muscles in the forearm contracting, pulling on tendons that attach distal to (beyond) the wrist. If the tendons, muscles, or nerves supplying these muscles are damaged or otherwise not working as they should be, wrist drop may occur. The following situations may result in wrist drop: Types. Types of wrist drop are distinguished by the nerves affected: Diagnosis. The workup for wrist drop frequently includes nerve conduction velocity studies to isolate and confirm the radial nerve as the source of the problem. Other screening tests include the inability to extend the thumb into a "hitchhiker 's sign". Plain films can help identify bone spurs and fractures that may have injured the nerve. Sometimes MRI imaging is required to differentiate subtle causes. Treatment. Initial treatment includes splinting of the wrist for support, along with osteopathic medicine, physiotherapy and occupational therapy. In some cases, surgical removal of bone spurs or other anatomical defects that may be impinging on the nerve might be warranted. If the injury was the result of pressure from prolonged use of improperly fitted crutches or other similar mechanisms of injury, then the symptoms of wrist drop will most likely resolve spontaneously within 8–12  weeks.