IGNIS | Page 6

The Skeletal System This strong, resistant structure is made up of bones and supporting cartilage and ligaments. Our form and structure comes from our skeletal system, and it protects our internal organs. We are also able to move because of our skeletal system, in conjunction with our muscular system. The bone marrow within the centre of bones also produces blood cells. There are several types of bones, which are generally classified into the following groups: Clavicle Humerus Long bones These are bones such as the femur. They are longer than they are wide, and are the main bones in the limbs. These bones grow more in childhood than the other types and are responsible for most of our height. They tend to have a central section which lies between two end points called the epiphyses. Radius Ulna Short bones These are bones such as the heel bones which are about as long as they are wide and can often be round or cubed in shape. Flat bones Femur The ribs, hips and most bones of the cranium are flat bones. They range in size and shape but they are all very thin in one direction. Irregular bones These take various shapes that don't fit the pattern of long, short or flat bones. For example the coccyx and wedge-like sphenoid bones in the skull are irregular bones. Fibula Tibia Sesamoid bones These bones are small and round. These form after birth to protect tendons from stress and strain at the joint. The patella is a sesamoid bone. Cuneiforms Metatarsals Phalanges 6 IGNIS