How is the canal of Guyon divided in the anatomy of ulnar neuropathy?

Updated: Jun 08, 2018
  • Author: Charles F Guardia, III, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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The canal of Guyon may be conveniently divided into 3 zones as follows:

  • Zone 1 (encompassing the area proximal to the bifurcation of the ulnar nerve) - Compression in zone 1 causes combined motor and sensory loss; it is most commonly caused by a fracture of the hook of the hamate or a ganglion

  • Zone 2 (encompassing the motor branch of the nerve after it has bifurcated) - Compression in zone 2 causes pure loss of motor function to all of the ulnar-innervated muscles in the hand; ganglion and fracture of the hook of the hamate are the most common causes

  • Zone 3 (encompassing the superficial or sensory branch of the bifurcated nerve) - Compression in zone 3 causes sensory loss to the hypothenar eminence, the small finger, and part of the ring finger, but it does not cause motor deficits; common causes are an aneurysm of the ulnar artery, thrombosis, and synovial inflammation

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