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Your bones

bones; body; marrow; skeleton; tendons; ligaments; ribs; legs; arms; muscles; skull; spine; joints; bone; joints; backbone; vertebra; scrimshaw; whale;

Contents

What are bones?

We all have bones. If we didn't, we would be like jellyfish!

Bones make up the framework of our bodies. We call this framework the skeleton.

Bones are living, growing and changing parts of our bodies. Babies' skeletons are made up from more than 300 parts, but by the time we become adults we only have 206 bones!

No, we haven't lost any! It's just that some of our baby bones are made, partly or completely, of cartilage (say car-til-ej). As we grow bigger and heavier, cartilage is slowly replaced by harder bone. Some smaller bones join together to make one bigger bone.

the skeleton

By the time we have finished growing, at about 25 years old, our bones are as big as they are going to get.

Most bones have 4 parts:

  1. The outside part of bone is called the periosteum (say per-ee-oss-tee-um). This is a thin but very dense layer that has the nerves and blood vessels which nourish the bone.
  2. Compact bone is next. It is smooth and very hard.
  3. Cancellous (say can-sel-us) bone comes next, and this looks a bit like a sponge but is much stronger.
  4. On the very inside of many bones is the bone marrow. It looks a bit like a jelly and it makes new blood cells for the body.

What bones do

The bones of the skeleton give us our shape and our posture. Without our spine (backbone) and leg bones we would be unable to stand erect.

Bones also protect the softer parts of our bodies.

  • The skull is like a natural helmet which protects the brain.
  • The spine protects the nerves in the spinal column.
  • The ribs make a shield around our lungs, heart and liver.
    broken bones

Bones are great team players!

  • They act as a base for muscles, ligaments and tendons. Ligaments connect bones to bones, and tendons connect muscles to bones. Our topic 'Your muscles' will tell you more.
  • They all work together to help us move around.

Your skull

When a baby is born, its skull has spaces between its bones. This is to make it easier for the baby to be born.

  • If you look at a new baby you can see that there is a soft spot - called the fontanelle - on the top of its head, which is a space between some of the skull bones.
  • As babies grow, the bones of the skull join together and harden.

Different bones in the skull have different jobs.

  • Some bones protect the brain. You can feel the bone at the back of your head and your forehead.
  • Some bones make the framework for your face. You can feel the bones around your eyes.
  • Some bones in the middle part of your ear carry sound from your eardrum to the inner ear. Have a look at the topic Ears – how your ears work for more about these bones.
  • You can feel the jawbone under your chin and where it hinges just under your ear. It is the only bone in your skull that you can move.

Your spine

the spineThe spine has 26 bones which are like circles with wings on the sides and back. They are called the vertebrae (say ver-tu-bray). There are small discs made of cartilage between each vertebra. They act like shock absorbers and also stop the bones rubbing against each other. There is also a hole through each of the vertebra where the spinal cord goes.

  • The top 7 are called the cervical (say ser-vik-al) vertebrae and they support your head and neck.
  • The next 12 are called the thoracic (say thor-ass-ik) vertebrae. These hold one end of your ribs.
  • The next 5 are the lumbar vertebrae.
  • The next, the sacrum, is a large bone that is actually made of 5 vertebrae fused (joined) together.
  • At the bottom of the spine is the coccyx (say cok-six), which is one bone made of 4 small vertebrae fused together. (Some people call this the monkey bone or tail bone. Can you work out why?)

Your ribs

Ribs make a protective cage around your lungs, liver and heart.

skeletonThere are usually 12 pairs of ribs, each pair attached to the spine at the back. Each rib is attached to the ribs above and below it by muscles and ligaments.

  • At the front of the body the top 7 ribs are attached to the sternum (or breast bone).
  • The next 3 pairs are joined to the ribs above, and to the sternum, by cartilage.
  • The last 2 pairs of ribs are called the ‘floating' ribs. But don't panic! They are not attached to the sternum but they are fastened to the spine at the back. If you look at the diagram above, you can see that it's OK! They are not floating around the body and they don't have sharp edges sticking out!

Your arms

Each arm is fastened to the scapula (the shoulder blade) at the back, (which is a triangle shaped bone near the top of the ribs) and to the clavicle at the front (the collar bone).

The arm has 3 bones - the humerus (say hew-mer-us), the radius (ray-dee-us) and the ulna (ul-na).

The humerus is the bone between your shoulder and the elbow. That's the one that really hurts when you bang it. It's sometimes called the 'funny bone' because 'humerus' sounds like 'humorous', which is another word for funny or amusing.

The radius and ulna bones go from the elbow to the wrist.

wonderful handsAt the end of the radius and ulna is your wrist. Your wrist has 8 small bones, so it is really flexible.

In each hand there are 19 bones! Your hands are so amazing that we have a whole topic about them, so look up Your wonderful hands, and prepare to be amazed!

 

Your legs

Your legs are fastened to your pelvis at the hips. The pelvis is shaped like a bowl and supports the contents of your tummy.

Legs need to be large and strong to support the rest of the body.

  • The femur (fee-mer) is the largest bone in the body and it goes from the pelvis to the knee.
  • Another bone called the patella ( pat-ell-a), or kneecap, covers the knee joint to protect it.
  • Below the knee there are 2 bones. These are the tibia (tib-ee-a) and the fibula (fib-you-la). They join up to a large bone in the ankle called the talus (tal-uss).
  • There are 6 other bones here so you can move your ankle around but you cannot move it as much as you can move your wrist.
    your feet

Your feet and ankles have a total of 52 bones in them, and as they are very important, they have their own topic too.  Look up Look after your feet to find out more.

Your joints

Where two bones meet is called a joint.

  • Some joints are fixed and don't move - for example, the joints in your skull, before they have grown together.
  • Some joints move a little, like the joints in your spine.
  • Some joints move a lot.

There are two kinds of moving joints.

  • Hinge joints act like the hinge on a door which allows it to open and shut.
  • Some joints are ball and socket joints. These allow movement in all directions.
    exercise

OK, can you work out which joints are hinge joints and which are ball and socket joints? Just move your body around and the answers are easy to find! (Your knees and elbows are hinge joints and your hips and shoulders are ball and socket joints.)

Dr Kim says 

You only get one body, so you need to make sure that you look after it!

  • Dr KimEat healthy food, especially dairy foods, which give your bones the calcium they need.
  • Get plenty of exercise and make sure that you protect your bones when you play sport. Always wear the right sports equipment for the sport you are playing.
  • Wear a helmet when you are on a bike.
  • Wear a helmet, elbow and knee guards when you're skate-boarding, skating or riding a scooter.
  • Look after your back. Our topic 'Good posture - looking after your back' will tell you how.

Interesting 'boney' facts

Olden daysIn the olden days, whale bones were used to make corsets - for women and men. These corsets would squash in the person's body so that they looked slimmer or a different shape.

Sounds painful doesn't it?

Men who worked on the whaleboats would often be at sea for weeks. Some of them would carve pictures onto whalebones or carve the bone into all sorts of things. This is called scrimshaw.

Animal bones have been used for playing games for thousands of years. Jacks or knucklebones and dice used to be made of bones - nowadays they are usually made of plastic.

What boney facts do you know?

Maybe you have heard the Gospel song 'Dem dry bones'. It's from the bible story about Ezekial who found himself in a valley full of dry bones and caused them to come alive by God's command. If you want to hear and read the song you could go to http://www.kididdles.com/lyrics/d009.html 

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We've provided this information to help you to understand important things about staying healthy and happy. However, if you feel sick or unhappy, it is important to tell your mum or dad, a teacher or another grown-up.

 

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