Wrist drop

The patient is unable to extend the wrist.
There is weakness of extension of the fingers.

What are the possible causes of wrist drop?
  • Classically it is caused by radial nerve compression in the spiral groove.  This may be 'Saturday night palsy' of an intoxicated individual sleeping with the arm across the back of a chair, or a pressure palsy in an anaesthetised patient.
  • It can also be caused by radial nerve compression in the axilla, for example pressure from crutches or rarely neoplastic involvement of axillary glands.
  • Injury at the brachial plexus (the posterior cord) results in a wrist drop and also weakness of elbow extension
  • Very rarely: an isolated C7 lesion

What are the nerve roots of the radial nerve?
C5 to T1

What sensory area relates to the radial nerve?
Back of hand and arm.

What muscles are innervated by the radial nerve?
  • C6: brachioradialis
  • C7:  triceps, extensor carpi radialis longus and extensor carpi ulnaris
  • C8: extensor digitorum, extensor pollicis longus and extensor pollicis brevis
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