See the crazy picture shown above? That freaky little creature is how our brains see the inside of our body.
The idea of how our brain depicts our body started in the 1930s when Wilder Penfield began poking around live brains of epilepsy patients. Wilder noted what part of the brain affected which body functions they controlled and how that part of the brain made people feel. Wilder’s experiments led to a distorted view of how the brain sees our body, that view is the picture above known as the cortical homunculus.
Basically cortical homunculus shows what part of the bodies are considered the most important by the brain.
Here’s a real depiction of Wilder’s work (non-3d):
If you think about it, the representation of the arms and legs makes sense, since the brain wouldn’t have to focus on them and would focus on placing hands and feet in the right area at which point the arms and legs will follow. Whereby hands, tongues and genitals are all necessary for surviving and populating the environment so they too would be more represented by the brain. [io9 via Psychweb]