"We all know what bodies look like from the outside. This cortical homunculus is how your brain sees your body from the inside.
In the 1930s, Wilder Penfield performed surgeries on patients with epilepsy. While he had a live brain on the table, he figured he might as well poke around a bit. The doctor gathered data, finding out which parts of the cerebral cortex control which voluntary body functions and feeling. What he discovered was a vastly distorted view of the human body: the cortical homunculus."