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31 July 2014
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You are here: BBC Science > Human Body & Mind > The Body > Skeleton
Fact files

Skeleton - Spine

S-shaped spine: Prevents shock to your head when you walk or run

Spinal cord protection: Your bony spine encases your delicate spinal cord

Vertebrae: 33 vertebrae make up your spine

Column of ring-like bones

Also known as your backbone, your spine is a strong, flexible column of ring-like bones that runs from your skull to your pelvis. It holds your head and body upright and allows you to bend and twist your body. It also offers protection to your spinal cord - a large bundle of nerves that runs through the cavity in the centre of your spine that relays messages between your brain and the rest of your body.

Vertebrae

Your spine is made up of 33 irregularly shaped bones called vertebrae. Each vertebra has a hole in the middle through which the spinal cord runs. The spinal cord can be divided into five different regions, from top to bottom:

  • Your 7 cervical vertebrae support your head and neck and allow you to nod and shake your head
  • Your ribs attach to your 12 thoracic vertebrae
  • Your five sturdy lumbar vertebrae carry most of the weight of your upper body and provide a stable centre of gravity when you move
  • Your sacrum is made up of five fused vertebrae. It makes up the back wall of your pelvis
  • Your coccyx is made up of four fused vertebrae. It is an evolutionary remnant of the tail found in most other vertebrates

Shock absorbers

Sandwiched between your vertebrae are pads of tough, fibrous cartilage called intervertebral discs that cushion your vertebrae and absorb shock. These discs, together with the curved, S-shape of your spine, prevent shock to your head when you walk or run.

Flexibility

The joints between individual vertebrae aren't very flexible. But working together they give the spine a wide range of movement, allowing you to arch backwards, bend forwards and twist from side to side. During strenuous movement, strong ligaments and muscles around your vertebrae stabilise your spine and help to control movement.

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