Erbs (or brachial) palsy occurs in about two out of every 1,000 child deliveries, when a baby suffers injury to the brachial plexus. The brachial plexus is a group of nerves that travel from the spinal cord up the arm, supplying the arms and hands. Erbs palsy happens most often during delivery when excessive pressure is put on the baby's head, neck, or shoulder because of difficulty delivering the shoulder area (known as "shoulder dystocia"). The condition occurs most frequently in babies of higher-than-average birth weight, and can happen when forceps or vacuum devices are used with too much pressure during delivery. The brachial plexus is simply stretched too far until important nerves are torn or ruptured. Symptoms of Erbs palsy can include paralysis or limpness in a baby's arm, limited or no movement in hands and fingers, and loss of sensation in the hands and fingers. Often the baby will simply hold the affected arm very close to the body, and will appear to be unable to move the arm itself, the hands, or the fingers.