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Wheeless' Textbook of Orthopaedics

Ulnar Nerve


- See
      - Cubitbal Tunnel Syndrome
      - Differential Dx: Ulnar Nerve Dysfunction:
      - Martin Gruber Anastomosis
      - Ulnar Nerve Blocks:
      - Ulnar Nerve in Condylar Fractures:

- Anatomy:
    - brachial plexus:
           - C8 and T1 nerve roots give rise to the medial cord which in turn, forms the ulnar nerve;
    - ulnar nerve passes distally, just medial to axillary artery, pierces medial intermuscular septum halfway down the arm, passes back over
           medial head of triceps, around posterior aspect of medial epicondyle, & enters forearm between two heads of FCU;
    - anatomy and sites of compression in the cubital tunnel:
    - just below elbow, it sends branches to FCU  & ulnar half of FDP;
    - it passes down forearm under FCU , & then into Guyon's  canal;
    - dorsal sensory branch:
           - the nerve emerges from the medial border of the FCU about 5 cm proximal to the pisiform;
           - supplies dorsoulnar aspect of the hand and the ulnar 1 1/2 fingers;
    - terminal branches in the hand: 
           - guyon's canal:
           - superficial cutaneous branch to ulnar portion of palm & volar surfaces of ulnar 1 1/2 fingers,
           - deep motor branch passes adjacent to hook of hamate;
           - deep branch, innervating hypothenar muscles & third & fourth lumbricalesadductor pollicis, all interossei, & deep head of  FPB;
    - references:
           - The lateral root of the ulnar nerve.
           - General Orthopaedics: The Anatomy of the Distal Ulnar Tunnel.
           - The Dorsal Branch of the Ulnar Nerve: An Anatomic Study.
           - Palmar cutaneous branch of the ulnar nerve.   
           - Distribution pattern of the deep branch of the ulnar nerve in the hypothenar eminence.
           - A Neural Loop of the Deep Motor Branch of the Ulnar Nerve: An Anatomic Study
           - A variation in the path of the deep motor branch of the ulnar nerve at the wrist


- Trauma to Ulnar Nerve: (see: nerve repair)
    - combined lesions of the median and ulnar nerves:
    - high ulnar nerve lesions
    - low ulnar nerve injury
    - division of ulnar nerve at wrist results in paralysis of all small muscles of hand except first & second lumbricales & most of thenar muscles;
    - paralysis of adductor pollicis produces Froment's sign;
           - when grasping piece of paper between thumb and index finger, FPL fires (IP joint flexion) since adductor does not work;
    - if ulnar nerve is divided below mid-forearm, ulnar claw hand is produced; (low ulnar nerve lesions);
           - w/ this lesion, 4th & 5th fingers are hyperextended at MP joints by long extensors but flexed at interphalangeal joints;
           - this posture is sometimes called hand of benediction;
    - if ulnar nerve lesion is above midforearm, clawing of ulnar two fingers does not occur, because extrinsic
           muscles producing IP joint flexion are also denervated (see high ulnar nerve lesion);
    - in complete claw  hand, produced by low lesion of median nerve & ulnar nerves, MP joints are
           extended & interphalangeal joints flexed by still-functional extrinsics;
    - references:
           - Repair of median and ulnar nerves. Primary suture is best.
           - Epiperineurium-fascial stitches along the stumps of a transected nerve. An additional method for closing the gap in the nerve trunk.
           - Experience with the free vascularized ulnar nerve graft in repair of supraclavicular lesions of the brachial plexus.
           - The results of secondary microsurgical repair of ulnar nerve injury.


- Cubital Tunnel Syndrome:
    - w/ severe cases of cubital tunnnel syndrome, there will be decreased two point sensory distribution of ulnar nerve
           as well as muscle weakness and/or muscle wasting of intrinsic innervated by the ulnar nerve;
    - clinical findings include positive Froment's test, wasting of first dorsal interosseous muscle, inability to
           cross index and middle fingers, & clawing of ring & small fingers;


- Entrapment of Ulnar Nerve at Wrist:
    - clinical findings:
          - positive Tinel's sign on percussion over ulnar nerve at guyon's canal;
          - positive Phalen's test w/ paresthesias in ring & small fingers
                - it will not show loss of sensation over dorsoulnar aspect of hand;
          - increase in two point discrimination;
          - changes with nerve conduction studies and electromyograms;
          - pts may also develop claw hand
    - diff dx:
          - ganglion (produces motor and sensory deficit)
          - frx (frx of 5th CMC or hook of hamate)
          - anomalous muscles;
                - anomalous muscle belly at level of the wrist, which includes, palmaris brevis profundus, ADM, FDM, and FCU;
          - thrombosis of ulnar artery or SPA;
          - synovitis;
    - treatment:
          - w/ compression of ulnar & median  nerves at wrist, ulnar nerve symptoms may improve with carpal tunnel surgery alone


  Clinical features of paralytic claw fingers.

  Acute ulnar neuropathy with fractures at the wrist.

  The extrinsic blood supply of the ulnar nerve at the elbow: an anatomic study.

  Tardy ulnar nerve palsy caused by cubitus varus deformity.

  Three tendon transfer methods in reconstruction of ulnar nerve palsy

  Restoration of Pinch Grip in Ulnar Nerve Paralysis: Extensor Carpi Radialis Longus to Adductor Pollicis and Abductor Pollicis Longus to First Dorsal Interosseus Tendon Transfers



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, April 11, 2012 11:15 am