In children and young adults the periosteum is thicker. This helps to protect the bone. Young bone bends further before breaking, has a better blood supply, and heals more quickly than adult bone. Long bones, such as those in your arm and leg, are made up of bone marrow, surrounded by compact bone. These areas are more susceptible to injury than the fused ends of adult bone and are important in ensuring your bones grow properly.
Osteoporosis is a disease of bones where they become weak and fragile in later life.
There is evidence to suggest that exercising while you are young may help make your bones stronger and protect you from this disease. Joints Joints occur where two bones meet. Most of the joints in your body are freely moving joints called synovial joints. These allow you to bend, and jump, and stretch. Muscles are attached to bones by cord-like extensions called tendons.