Ulnar Nerve Anatomy and Pathology

Common causes of mononeuropathy (single nerve damage):

  • Entrapment neuropathies
    • Anatomical constraint of the nerve
      • Genetic, but overuse/ trauma/ long- term pressure on the nerve further complicates the problem
    • Non-entrapment neuropathies
      • Direct injury to the nerve
      • Pressure on the nerve from nearby swelling or bone/ joint injuries
      • Inflammatory conditions

Locations of Ulnar Nerve Damage

  1. Posterior to the medial epicondyle of the humerus (most common)
    1. No muscles are innervated by the ulnar nerve above the elbow, however, effects of damage to the nerve in this location are noticeable from the elbow down
  2. Cubital Fossa (anterior elbow)- where the humerus and ulna come together
    1. May result in extensive sensory/ motor loss in the hand
      1. Decreased motor control in the intrinsic muscles of the hand, including: power in the wrist, flexion of the wrist, and the hand may be drawn in the direction of the thumb due to an imbalance of muscle contractions
      2. The individual may experience difficulty pulling the pinky/ ring fingers to the palm when trying to make a fist
    2. Usually results in “claw hand”
  3. At the wrist
    1. Guyon Syndrome/ Ulnar Canal Syndrome: damage to the peripheral ulnar nerve between the pisiform and hook of the hamate bones in the hand/ wrist
      1. Characterized by decreased sensation in the pinky/ half of the ring finger and weakness in the intrinsic hand muscles
        1. With this injury as compared to an injury of the ulnar nerve higher up the arm, the individual’s ability to flex the pinky/ ring finger and radial deviation is relatively unaffected.
        2. Specific muscles believed to be affected:
          1. Dorsal Interossei (abducts digits away from middle finger)
          2. Abductor Digiti Minimi (moves pinky away from ring finger)
        3. In the hand
          1. Symptoms (sensory/ motor loss) are observed from the immediate area of the trauma/ injury distally through the ends of the fingers


  • RICE
    • Rest to allow the trauma/ damage to heal
    • Ice/ cold pack
    • Compression by using a compression bandage (it’s too tight if you experience skin discoloration, pins/ needles, numbness, or temperature changes in the skin)
    • Elevate the arm above the heart
  • Promote proper positioning/ ergonomics of the arm in waking/ non-waking hours
  • Avoid pressure application to the palm & pinky side of the wrist, such as while typing
  • Surgery as a last resort

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