With the head now free, the shoulders remain the last awkward part to be delivered as the rest follows easily. The surgeon clasps the head in both hands and gently eases the foetus out. Care must be taken to ensure the angle between the head and shoulder on either side is not too great, as excessive stretching applied here could lead to damage of the superior brachial plexus roots, i.e. the nerves supplied by C5 and C6. The resulting injury produces paralysis of the deltoid, biceps brachii, brachialis and brachioradialis muscles. This is known as Erb-Duchenne paralysis.