Final answer:
Immobilizing the arm in the event of a rib cage fracture helps prevent further injury, supports proper bone alignment for healing, and alleviates pain by restricting movement at the fracture site.
Step-by-step explanation:
Immobilizing the arm of a victim of a rib cage fracture is essential to prevent further injury and to support proper healing. When a person sustains a fracture to the clavicle, which is one of the most commonly fractured bones due to falls or direct impact, it often results in the arm and lateral clavicle fragment dropping due to the weight of the limb. This causes pain and may encourage the individual to support the limb with their other hand. Immobilization of the affected arm using an arm brace or sling ensures alignment of the bone fragments, minimizes movement at the fracture site, and prevents damage to important underlying structures such as blood vessels and nerves. In addition, it alleviates pain by restricting the pull of muscles across the shoulder that might otherwise cause the fracture fragments to override and displace, leading to improper healing.