Skeletal System

Multicellular animals need some form of support to maintain their body structure. Various groups of organisms show supportive skeletal structures either outside the body, inside the body, or both. Skeletal structures present on the outer surface of the body are called the exoskeleton; those present inside the body form the endoskeleton.

Bones and cartilage form the major endoskeletal components in humans and other vertebrates. Exoskeletal components differ across groups of animals, from lower to higher forms, and include chitinous structures, nails, horns, hooves, scales and hair, among others.

The human skeletal system is made up of cartilage (slightly pliable) and bone (with a hard matrix), which together form the framework of the body. The skeletal system:

• gives the body its shape, which in turn gives us our identity;
• protects delicate internal organs, helping the body function smoothly;
• provides joints between bones that permit movement and locomotion;
• provides a firm surface for the attachment of muscles;
• serves as a reservoir of calcium; and
• provides an important site for haemopoiesis (blood cell formation). …