MEPX
Chapter 3 of 14All chapters
  1. 1How the body is organised
  2. 2Cells and tissues
  3. 3The skeleton
  4. 4Muscles
  5. 5Heart and circulation
  6. 6Blood
  7. 7Lungs and breathing
  8. 8Digestion
  9. 9Kidneys and liver
  10. 10The nervous system
  11. 11The brain
  12. 12Hormones
  13. 13Skin and senses
  14. 14The immune system

Chapter 3 of 14

The skeleton

Structure, protection and blood production.

Bones by the numbers

An adult skeleton has 206 bones. A newborn starts with about 270, and several fuse while growing, which is why the count drops rather than rises.

  • The femur is the longest bone and the stapes in the ear the smallest.
  • Bone marrow makes red and white blood cells, so the skeleton is also a factory.

Joints

Joints range from fixed, as in the skull, to freely moving ball and socket joints at the hip and shoulder. Cartilage cushions the surfaces and ligaments hold bone to bone.