How do bones grow and develop?

Bones provide structural support to the whole body and work together with muscles and joints to allow freedom of movement. The adult human body contains 206 bones, which are made up of connective tissue and specialized bone cells.1 The formation of the skeleton begins early, during the first few weeks after conception. In fact, by the end of the eighth week of pregnancy, the majority of the skeleton is already laid down with cartilage and connective tissue membranes, and the process of ossification (the process whereby tissue becomes bone) begins.2 the embryo is soft but gradually turns into hard bone throughout infancy and childhood.3

There are two ways in which bones grow and mature which depends on the type of bone.2 Types of bone include:4

  • Long bones e.g. the arm and leg bones
  • Short bones e.g. the small bones in the wrists
  • Irregular bones e.g. the vertebra
  • Flat bones e.g. the ribs and bones in the skull

Long, short and irregular bones grow by a process where cartilage is replaced by bony tissue. Most of the bones of the skeleton are formed in this manner. Flat bones, like those in the skull, develop by a different process, where sheet‐like connective tissue membranes are replaced with bony tissue. During childhood the bones grow very rapidly and in order to form properly, require energy, a well balanced diet and a healthy environment.2 Consuming enough calcium in childhood and adolescence may even reduce the risk of fractures and osteoporosis later in life.5