The skeleton does two very important jobs. It holds the body up, and it protects the delicate organs of the body. When a baby is born, it has about 270 bones in its body. These are small and quite soft, and as the child gets older some bones fuse together, so that there are about 206 by the time the child is fully grown. The skeleton has joints which enable it to move easily. The most flexible joints are the ones like that at the hip – these are called ball and socket joints. Other joints don’t move at all – the skull is an example of this. Although it is made of many different bones, most of these don’t move, the only one that does being the jaw bone. The skull protects the brain from injury, while the rib cage protects the heart and lung, and the backbone (which is a long chain of small bones) protects the spinal cord, the ‘main road’ of the nervous system.