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What is ulnar paradox?

Asked by FCU 

Ulnar nerve injury results in clawing of hands. Clawing is characterized by:
  • Hyperextension of MCP joints: Unopposed action of extensors (lumbricals paralyzed)
  • Injury at wrist (lower level):
    • FDP spared: Flexion of IPJ (more clawing visually)
  • Injury at elbow (higher level):
    • FDP injured: No flexion of IPJ (less clawing visually)
Lesions at the elbow often have less clawing, since the ulnar half of FDP is paralyzed. This phenomenon is known as ulnar paradox.