• How fast do nerves act?
  A nerve signal is a tiny pulse of electricity. It travels at about 3 ...

• What gives hair its color?
  The color of your hair is determined mainly by the pigments (colored ...

• Which joints move the least?
  Your skull is made up of more than 20 bones fused together in joints ...

• What are ligaments?
  Ligaments are strong, bendy straps that hold together the bones in a ...

• What is a vertebra?
  A vertebra is a knobbly bone in your spine. The 26 vertebrae fit ...

• Which joint moves the most?
  The shoulder joint is a ball and socket joint and it allows the ...

• What’s inside a bone?
  Inside a bone is a crisscross honeycomb of lighter bone. Blood ...

• Which is the longest bone?
  The thigh bone in the upper part of your leg is the longest bone in ...

• Which is the smallest bone?
  The smallest bone is called the stirrup and is no bigger than a grain ...

• Which is the biggest muscle?
  The biggest muscle is the gluteus maximus in the buttock. You use it ...