Which part of the bone structure is known to cover the outer surface?

The periosteum is the layer that covers the outer surface of bones. It is a dense, fibrous membrane that not only protects the bone but also serves as an attachment point for tendons and ligaments. This membrane plays a critical role in the growth and repair of bone by housing osteoblasts, which are essential for bone formation. Additionally, the periosteum contains blood vessels and nerves, contributing to the nourishment and sensation of the bone tissue.

In contrast, the other components listed serve different functions. The marrow is found within the central cavity of long bones and is responsible for producing blood cells. Cartilage is a smooth, flexible tissue that typically covers the ends of bones at joints, reducing friction and absorbing shock. The growth plate, or epiphyseal plate, is a region of growing tissue near the ends of long bones in children and adolescents that is involved in the lengthening of bones as they develop.

Understanding the role of the periosteum is crucial for grasping how bones grow and heal, highlighting its importance in the overall anatomy of the skeletal system.