ERB'S PARALYSI
Site of injury :
One region of the upper trunk of the brachial plexus is called Erb's point. Six nerves meet here. Injury to the upper trunk causes Erb's paralysis.
CAUSE OF INJURY :
Undue separation of the head from the shoulder, which is commonly encountered in the following.
i. BIRTH INJURY
ii. FALL ON THE SHOULDER
iii. DURING ANAESTHESIA
NERVE ROOT INVOLVED:
Mainly C5 and partly C6.
MUSCLE PARALYSED:
Mainly biceps brachii, deltoid, Brachialis and Brachioradialis. Partly Supraspinatus, Infraspinatus and Supinator.
DEFORMITY AND POSITION OF THE LIMB:
ARM:Hangs by the side, it is adducted and medially rotated.
FOREARM: Extended and pronated.
The deformity is known as `policeman's tip hand' or waiter's tip hand or `porter's hand'.
DISABILITY:
⚫ Abduction and lateral rotation of the arm at shoulder joint.
⚫Flexion and Supination of the forearm.
⚫Biceps and Supinator jerks are lost.
⚫ Sensation are lost over a small area over the lower part of the deltoid.