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Brachial Plexus



  1. Brachial plexus is formed by confluences of nerve roots from C5 to T1
  2. The plexus consists of roots, trunks, divisions, cords and branches.


  1. These are constituted by anterior primary ramiof spinal nerves CS' C6' C7' C8' T1.


  1. Roots C5 and C6joint to formupper trunk.
  2. Root C7 forms the middle trunk.
  3. Root C8 and T1 join to form lower trunk.
  4. Each trunk divides into ventral and dorsal divisions which join to form cords.


  1. The lateral cord is formed by the union of ventral divisionsofthe upper and middle trunks.
  2. The medial cord is formed by the ventral division of the lower trunk.
  3. The posterior cord is formed by union of the dorsal divisions of all the three trunks.

Branches of brachial plexus

Branches of brachial plexus arise from different anatomical segments: -

  1. Branches of the roots
    1. Nerve to serratus anterior (long thoracic nerve)(Cs, C6, C7
    2. Nerve to rhomboideus (dorsal scapular nerve) (C5
  2. Branches ofthe trunks
    These arise only from the upper trunk which gives two branches.
    1. Suprascapular nerve (C5, C6)
    2. Nerve to subclavius (C5, C6)
  3. Branches of the cords
    1. Branches of lateral cord
      i. Lateral pectoral (C 5 -C7)
      ii. Musculocutaneous (C5-C7
  4. Branches of medial cord
    1. Medial pectoral (C8, T1)
    2. Medial cutaneous nerve of arm (C8' T1,)
    3. Medial cutaneous nerve of forearm (C8' T1)
    4. Ulnar (C7, C8, T1). C7
    5. Medial root of median (C8, T1)
  5. Branches of posterior cord
    1. Upper subscapular (C5, C6)
    2. Nerve to latissimus dorsi (thoracodorsal) (C6, C7, C8)
    3. Lower subscapular (C5, C6)
    4. Axillary (circumflex) (C5, C6)
    5. Radial (C5-C8,T1)
  • If the contribution of C4 nerve root also occurs, itis called prefixed to plexus.
  • If the contribution of T2 nerve root also occurs, it is called postfixed to plexus.

Erb's Paralysis

  1. One region of upper trunk (C5, C6)of the brachial plexus is called Erb's point where six nerves meet.
  2. Injury at this point results in Erb's paralysis.
  3. The injury is due to undue separation of the head from the shoulder, which may be seen in : -
    1. Birth injury
    2. Fall on the shoulder

Clinical features of Erb's palsy

  1. Muscles paralysed: Mainly biceps brachii, deltoid, brachialis and brachioradialis. Partly supraspinatus, infraspinatus and supinator.
  2. Deformity (position of the limb)
    1. Arm:Hangs by the side; it is adducted and medially rotated
    2. Forearm : Extended and pronated
      The deformity is known as 'policeman's tip hand' or 'porter's tip hand'.
  3. Disability: The following movements are lost.
    1. Abduction and lateral rotation of the arm (shoulder).
    2. Flexion and supination of the forearm.
    3. Biceps and supinator jerks are lost.
    4. Sensations are lost over a small area over the lower part of the deltoid.

Klumpke's Paralysis

  1. Site of injury: Lower trunk of the brachial plexus.
  2. Cause of injury: Undue abduction of the arm, as in clutching something with the hands after a fall from a height,or sometimes in birth injury.
  3. Nerve roots involved: - Mainly T1 and partly C8.
  4. Muscles paralysed
    1. Intrinsic muscles of the hand (T1).
    2. Ulnar flexors ofthe wrist and fingers (C8).
    3. Deformity (position of the hand). Claw hand due to the unopposed action of the long flexors and extensors of the fingers. In a claw hand there is hyperextension at the metacarpophalangeal joints and flexion at the interphalangeal joints.
  5. Disability
    1. Claw hand
    2. Cutaneous anaesthesia and analgesia in a narrow zone along the ulnar border of the forearm and hand.
    3. Horner’ssyndrome if T1is injured proximal to white ramus communicans to first thoracic sympathetic ganglion. There is ptosis, miosis, anhydrosis, enophthalmos, and loss of ciliospinal reflex may be associated. (This isbecause of injury to sympathetic fibres to the head and neck that leave the spinal cord through nerve T1).
    4. Vasomotor changes: The skin area with sensory loss is warmer due to arteriolar dilation. It is also drier due to the absence of sweating as there is loss of sympathetic activity.
    5. Trophic changes: Long standing case of paralysis leads to dry and scaly skin. The nails crack easily with atrophy of the pulp of fingers.

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