Features of an ulnar nerve lesion at the elbow

The clinical features of an ulnar nerve lesion at the elbow include:

• wasting of the flexor carpi ulnaris and the ulnar half of the flexor digitorum:
  • is apparent on the inner aspect of the flexor surface of the forearm
  • weakness of flexor carpi ulnaris causes the hand to deviate to the radial side as the wrist is flexed
    
    
• wasting of the small muscles of the hand except the thenar eminence and the first two lumbricals
  
  
• clawing of the ring and little fingers (main en griffe):
  • loss of the 3rd and 4th lumbricals and all the interossei results in:
    • hyperextension of the metacarpophalangeal joints
    • flexion of the interphalangeal joints
      
      
• paralysis of the hypothenar muscles:
  • abolishes abduction of the little finger
    
    
• paralysis of the interossei:
  • abolishes abduction and adduction of the fingers
    
    
• paralysis of the adductor pollicis:
  • weakens adduction of the thumb which is most evident when a piece of paper is grasped in a pincer grip between thumb and index finger (Froment's sign)
    
    
• numbness and tingling:
  • over the two ulnar fingers and the ulnar border of the palm