Final answer:
Erb palsy is a birth injury to the brachial plexus that may result in weakness or paralysis of the arm, typically occurring during a difficult childbirth. It is characterized by the arm being held in a 'waiter's tip' position.
Step-by-step explanation:
Erb palsy, also known as "waiter's tip" position, is a form of birth injury that involves damage to the infant's brachial plexus—the network of nerves that sends signals from the spine to the shoulder, arm, and hand. This injury can occur during a difficult birth if the baby's neck is stretched to the side as the shoulders pass through the birth canal. The presentation includes a characteristic position of the arm, where the arm is adducted and internally rotated at the shoulder with an extended elbow, flexed wrist, and fingers, which resembles the position of a waiter's hand when receiving a tip, hence the nickname "waiter's tip."
Symptoms of Erb palsy may include loss of sensation in the arm, weakness, and paralysis. Treatment commonly involves physical therapy and, in severe cases, surgery. The condition is different from cerebral palsy, which is a more generalized disorder caused by injury to the developing brain either before, during, or shortly after birth, affecting body movements and muscle coordination.