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Median Nerve


The median nerve is also called labourer's nerve. The median nerve arises by two roots, one from the lateral cord (C5, 6, 7) and the other from the medial cord (C8, T1). The various muscles supplied by median nerve are: -

  1. In theforearm
    All the flexor muscles of the forearm, except the flexor carpi ulnaris and the medial half of flexor digitorum profundus to the ulnar two fingers. These muscles are: -
    1. Pronator teres                          
    2. Flexor digitorum superficialis                                
    3. Flexor pollicis longus
    4. Flexor carpi radialis            
    5. Flexor digitorum profundus (lateral half)                 
    6. Pronator quadratus
    7. Palmaris longus
  2. In hand
    Median nerve supplies: -
    1. Thenar muscles (except adductor pollicis): - Flexor pollicis brevis, opponenspollicisandabductor pollicisbrevi. *Adductor pollicis is supplied by ulnar nerve.
    2. First two lumbricals

Sensory supply by medial nerve is

  1. Lateral two thirds of palm
  2. Lateral three &half fingers on palmar side and distal phalanx of lateral three &half digits on dorsal side.

Aetiology of median nerve injury

The median nerve can be injured at the following levels: -

  1. In the arm: - It is injured, though rarely by cut injury with a sharp object.
  2. At the elbow: - It is commonly injured in the cases of supracondylar fracture of humerus and dislocation of elbow.
  3. At the wrist: - The median nerve is often injured by cut injury due to knife or glass.
  4. In carpal tunnel: - Injury at this level is rare. Pressure from dislocated lunate bonecan damage the nerve. Compression neuropathy (i.e., Carpal tunnel syndrome) is more common than injury.

Clinical features of median nerve palsy

Clinical features depend on the site of lesion: -

  1. High median nerve palsy
    1. Injury in arm or at elbow causes high median nerve palsy.
    2. All muscles supplied by median nerve are paralysed.
    3. In addition there is sensory loss in the thumb, index, middle and radial half of the ringfingers and lateral 2/3 of the palm.
    4. Following features are seen; -
      1. Flexion of distal IP joint of thumb is not possible (due to paralysis ofFPL).
      2. Benediction test: - Patient is unable to flex the index and middle finger on lifting the hand due to paralysis oflong flexors of these two fingers.
      3. Pen test: - Patient is unable to touch the pen, held above the thumb (due to APB paralysis).
      4. Ape thumbdeformity: - The thumb is adducted and laterally rotated so that the thumb lies in the same plane as the other fingers. It is due to over action of adductor pollicis (supplied by ulnar nerve).
      5. Loss of opposition due to paralysis of opponenspollicis.
      6. Atrophy ofthenareminence.
  2. Low median nerve palsy
    1. Injury at wrist or in carpal tunnel produces low median nerve palsy.
    2. Long flexors of fingers are spared and there is paralysis of thenar muscles only.
    3. Following features are seen; -
      1. Pen test for abductor pollicis brevis paralysis.
      2. Loss of opposition and abduction of thumb.
      3. Ape thumb deformity
      4. Loss of sensation of lateral 3 ½ fingers and lateral 2/3rdof palm.

In contrast to high median nerve palsy, pointing index and Benediction test are not seen as long flexors are spared in low median nerve palsy.



Ulnar Nerve

  1. Ulnar nerve is also called ‘musician’s nerve’ as it controls fine movements of the fingers. The ulnar nerve arises from the medial cord of the brachial plexus (C7-8, T1)(ulnar nerve receives its C7 fibres as a branch oflateral cord of these have not already passed to medial cord from ventral ramus of C7). Various muscles supplied by ulnar nerve are ; -
    1. In the arm                 Nil
    2. In the forearm
      Proximal 1/3rd           Flexor carpi ulnaris, medial half of flexor digitorum profundus

      Distai1/3rd                 Nil
    3. In hand
      Superficial branch      Hypothenar muscles

      Deep branch             Adductor pollicis,allinterosseiand medial two lumbricals

Note: Hypothenar muscles are; Palmaris brevis, abductor digit minimi, flexor digiti minimi, opponens digiti minirni.

  1. Sensory supply of ulnar nerve is : -
    1. Medial 1/3rd of the Palm (hypothenar area)
    2. Medial one & half fingers (whole little finger and medial halfofring finger).
    3. Autonomous zone of sensory supply for ulnar nerve is tip of little finger.

Ulnar nerve injury

Ulnar nerve injury may be high or low.

  1. High ulnar nerve palsy
    1. High ulnar nerve palsy is caused by injury proximal to the elbow.
    2. All the muscles supplied by ulnar nerve are paralysed and there is atrophy of hypothenar eminence.
    3. Sensory loss in the medial 1/3rd of the palm and medial one &half of fingers.
  2. Low ulnar nerve palsy
    1. Injury in distal-third offorearm or at wrist.
    2. Flexor digitorum profundus and flexor carpi ulnaris are spared.
    3. Muscles of Hand are paralyzed: -
      1. Hypothenar muscles: - Palmaris brevis, Abductor digiti minimi, flexor digiti minimi, opponens digit minimi.
      2. Adductor pollicis
      3. All interossei (Palmar &Dorsal) and medial two lumbricals (3rd&4th).
    4. Sensory loss is same as in high ulnar nerve palsy.

Claw hand

  1. In claw hand, there is hyperextension at metacarpophalangeal joint and flexion at interphalangeal joint.
  2. To understand the claw hand deformity, one should know the function offollowing muscles: -
    1. Lumbricals: - Their major function is to flex the metacarpophalangeal joint and extension of interphalangealjoint.
    2. Interossei: - Palmar interossei adduct the fingers while dorsal interossei abduct the fingers. In addition to these both palmar and dorsal interossei assist lumbricals to flex the metacarpophalangeal joint and to extend IP joint.
  3. Loss of these intrinsic muscles function results in loss of flexion at MP joint and extension at IP joint.
  4. Long flexors of fingers cause flexion ofIP joints and long extensors cause extension ofMP joints.
  5. Therefore, there is hyperextension at MP joint and flexion at IP joint.
  6. As you all know all interossei and 3rd&4thlumbricals are supplied by ulnar nerve, while 1st and 2ndlumbricles are supplied by median nerve.
  7. So, claw hand of 3rd&4thfinger will be seen in isolated ulnar palsyas 1st&2nd finger’s lumbricals (1st&2ndlumbricals) are spared (supplied by median nerve) →Ulnar claw hand.
  8. Claw hand of all fingers is seen in combined ulnar and median nerve palsy as all lumbricals and interossei are paralysed →True claw hand.

Ulnar paradox

  1. Ulnar claw hand is seen in lower ulnar nerve palsy not in high ulnar nerve palsy. It is called ulnar paradox.
  2. This is because in higher lesions long finger flexors (FDPof 3rd&4th finger) are also paralysed → IP jointflexion does not occur and therefore claw hand deformity is not seen.
  3. So,
    1. Claw hand is due to   →  Paralysis of intrinsic muscles (lumbricals &interossei)
    2. Ulnar paradox is due to  → Paralysis of medial half of FDP& ulnar claw hand does not occur in high ulnar nerve palsy

Among the all nerves, maximum disability of hand occurs in ulnar nerve injury as ulnar nerve supplies most of the intrinsic muscles of hand.

Disability is more in low ulnar nerve palsybecause claw hand occurs in low ulnar nerve palsy.

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