Final answer:
In pediatric care, the torso is typically immobilized first to provide stability and prevent further injury. An arm brace may be used to support underlying bone structure during healing, but ossification of the clavicle is unrelated to the immobilization process.
Step-by-step explanation:
When immobilization is necessary in a pediatric patient, medical professionals typically secure the torso first to the immobilization device. This is crucial because the torso is the central part of the body that provides structural stability. Immobilizing the torso first helps to prevent further injury to the spine and allows for the subsequent secure positioning of limbs, such as the use of an arm brace to support the underlying bone structure. It is important to note that a brace, in the context of orthopedic care, is an external device prescribed by an orthopedist to reinforce bones during the healing process. While the clavicle is the first bone to begin ossification, often within the fifth week of development, it does not directly relate to the process of immobilization in pediatric care.