Wrist drop

Wrist drop
The suprascapular, axillary, and radial nerves.
Classification and external resources
Specialty	rheumatology
ICD-10	M21.3
ICD-9-CM	736.05
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Wrist drop, also known as radial nerve palsy, is a condition where a person cannot extend their wrist and it hangs flaccidly. To demonstrate wrist drop, hold your arm out in front of you with your forearm parallel to the floor. With the back of your hand facing the ceiling (i.e. pronated), let your hand hang limply so that your fingers point downward. A person with wrist drop would be unable to move from this position to one in which the fingers are pointing up towards the ceiling.

In anatomical parlance, the forearm is the part of the body which 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 extensor carpi ulnaris, extensor digiti minimi, extensor digitorum, extensor indicis, extensor carpi radialis brevis, 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 also innervated by the radial nerve are supinator, extensor pollicis brevis, extensor pollicis longus, and abductor pollicis longus. Note that all these muscles are situated in the posterior half of the forearm (posterior when in the anatomical position). Also, brachioradialis, anconeus, triceps brachii, and extensor carpi radialis longus are all innervated by muscular branches of the radial nerve in the arm.

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