Erb's palsy is an injury to the upper brachial plexus (mainly the fifth and sixth cervical roots) related to birth trauma of newborns. Its occurrence is about 0.1 percent in spontaneous delivery, 1.2 percent in breech delivery, and 1.3 percent in forceps delivery. The result is partial paralysis of the muscles of the shoulder and flexors of the elbow such that the arm hangs at the side and internally rotated at the shoulder.