Which part of the bone is primarily involved in the growth of long bones during childhood?

The correct answer is the metaphysis, which is the region of the bone where growth occurs during childhood. This area contains the growth plate, also known as the epiphyseal plate, which is composed of hyaline cartilage. During periods of growth, new cartilage is formed at the epiphyseal side of the plate, and this cartilage is gradually ossified to bone on the diaphyseal side. This process allows the long bones to lengthen as a child grows.

As a child matures and reaches skeletal maturity, the metaphysis undergoes changes leading to the fusion of the epiphyseal plate and cessation of growth in length. Understanding the role of the metaphysis is crucial in grasping how long bone growth is regulated and how various factors can influence this process in a developing individual. The other parts of the bone, such as the epiphysis and diaphysis, play supportive roles in the structure and function of the bone but are not primarily responsible for the active growth of long bones during the childhood years.