The adult body is made up of 206 bones. The bones in our bodies help to give the body shape and they also help to protect different organs and systems that are located inside of the body.

Bones are made up of different material, but most bones are made up of the same types of materials.

The main bones of the human skeleton are

The SkullCranium, Mandible, and Maxilla
Shoulder girdleClavicle and Scapula
ArmHumerus, Radius, and Ulna
HandMetacarpals, Phalanges and Carpals
Chest Ribs and Sternum
SpineCervical area (top 7 vertebrae), Thoracic (next 12), Lumbar (bottom 5 vertebrae), Sacrum (5 fused or stuck together bones) and Coccyx
Pelvic girdleIlium, Pubis, and Ischium
LegFemur, Tibia, and Fibula
AnkleTalus and calcaneus
FootTarsals, Metatarsals, and Phalanges

Layers of Bones

The outside surface of the bone is called the periosteum. This part of the bone helps give the bone nourishment.

It has a thin membrane that has blood vessels and nerves and keeps the bone healthy.

The second layer is called the compact layer, and this is the hard part of the bone with the white color.

This layer is very smooth. Inside of the compact layer is a sponge looking layer called the cancellous.

The spongy part of the bone is made to help keep stress from hurting your bones, helping them not to snap or break in half when you bend or move.

The cancellous is not as hard as the compact bone. The cancellous bone has a job to protect the bone marrow that is located inside of the bone.

This marrow helps to make sure that the blood cells are protected and helps to make blood cells.

Bones Are Always Changing

Bones change from birth and through adulthood. The baby has around 300 bones when they are born, and these grow together as people get older.

Some baby bones are made up of cartilage which is a soft and flexible material that eventually is replaced by bone.

Protect Your Bones

It is important to try and make sure that you protect your bones as good as you can. Wearing a helmet when skating or riding a bike can help to protect your skull bone.

It is important to protect your skull bone because this bone helps to keep your brain safe.

Broken Bones

Bones can be broken by certain types of activities. Broken bones heal but this takes a lot of time and sometimes the bones do not heal back the same way that they were.

Cells inside of your bones help to rebuild the bone, just like skin cells can help to heal you if you get a scratch or a cut.


It is important to make sure to try to keep your bones healthy by drinking milk and eating things that contain calcium, so that your bones stay strong and do not break.

Calcium helps to keep bones strong. The bones are made to store calcium and other minerals and the bones grow for many years and need to be protected.

Facts About Bones:

  • The hand has 54 different bones.
  • Growth plates are located at the end of certain bones such as your arms and legs. These growth plates help you to grow and stay open until you reach the end of your growing.
  • Collagen is located inside of your bone and it replaces itself throughout your life.
  • Your bones help to protect you and to help make red blood cells that are needed in the body.
  • The stirrup located in the ear is the smallest bone in the body.
  • The femur is the longest bone in the body.
  • The toe bone is the most fragile bone in the body.
  • Osteoporosis is a bone disease that happens when the bone loses density and becomes thinner.

What Did You Learn?

  • What vitamin is needed to help keep bones strong and healthy? Calcium is an important vitamin that helps to keep bones strong and healthy.
  • How many bones are in the adult human body? The adult human body has 206 bones.
  • What happens to the other bones that babies are born with? Babies are born with 300 bones and as the baby gets older, the bones fuse together and this is why adults only have 206 bones.
  • What is the outer layer of the bone called that gives the bones nourishment? The outer layer of the bone is called periosteum and this layer gives the bones nourishment to stay healthy.
  • Why is it important to protect your bones? It is important to protect your bones because your bones help to protect vital organs such as the brain, the kidneys and more.