Using a skeleton, Dr. Nachlas discusses the body's skeletal system and explains how bones' rigidity protects the body's vital organs and offers attachment for muscles. He shows how a broken bone must have approximate broken edges, proper alignment of broken pieces, and immobilization of the bones in order to heal properly. Since plaster casts cannot always accomplish this, Dr. Nachlas details how bones can be splinted and immobilized internally with such metals as vitalium, tantalum, and stainless steel, which do not corrode or cause infection. He shows an x-ray of fractured leg bones held in place by long, stainless steel rods running down the marrow cavities. He also describes the correction of a difficult forearm fracture using a rod and interviews the woman who had the operation to correct this problem to prove how the metal rod strengthened and straightened her arm. Dr. Nachlas gives another example of how a fragment of bone was replicated with vitalium.