SKELETON

The skeleton is a framework of bones. It gives the body shape, protects the vital organs, such as the heart, brain and lungs, and provides attachments for muscles. The backbone, made up of smaller bones called vertebrae, helps to hold us upright. All the bones in the skeleton are living, and need a supply of blood. They also have nerves, as you will know if you have ever been kicked in the leg. The bones of the skeleton are light and strong. The joints allow them to move.

·        The strongest and longest bone in the body is the femur or thigh bone.

·        Babies have up to 300 bones, but some of these of gradually fuse together. There are 206 bones in the adult human body.

·        The centre of the bone is hollow. That is called cavity.

·        A baby has 29 bones in the skull. These join together by the time it is 18 months old to form a solid covering over the brain

·        The leg bones are wider at the ends; this helps to make them stronger. They are also hollow, which makes them lighter, and they are filled with a substance called bone marrow. The hard (compact) bone has a tough covering (periosteum). Under the compact bone layer is ‘spongy bone’, so called because of its honeycombed structure (though it is not soft). 

·        When a bone breaks, blood between the two ends clots. Cells in the bone’s outer lining or sheath increase, forming a layer of tissue over the break. New soft bone cells then start to grow at each end of the break, replacing the tissue.

·        A new-born baby is about 50 cm long; an average adult grows up to 176 cm tall. Bones keep growing as long as the body is alive. A soft area at each end of the bone is made up of cartilage; this is where growth takes place

·        The various bones of adult skull have fused together, so as to protect the delicate brain material underneath.