From a scientific perspective, "homunculus" refers to the brain's perception of the body. A certain percentage of sensory area in the cerebral cortex is connected to each body part; the image of the homunculus is the image of a man whose proportions reflect these relative areas. For example, a human's lips are much more sensitive than the upper arm. This is because more cortex area is devoted to the lips than to the upper arm; the image of the homunculus would therefore have very large lips and a very small, insignificant upper arm. Likewise, each fingertip would be much larger than any other part of the arm or hand.