The
human brain is the main organ of the human
central nervous system. It is located in the
head, protected by the
skull. It has the same general structure as the brains of other
mammals, but with a more developed
cerebral cortex. Large animals such as whales and elephants have
larger brains in absolute terms, but when measured using a
measure of relative brain size, which compensates for body size, the quotient for the human brain is almost twice as large as that of a
bottlenose dolphin, and three times as large as that of a
chimpanzee, though the quotient for a
treeshrew brain is larger than that of a human's. Much of the size of the human brain comes from the cerebral cortex, especially the
frontal lobes, which are associated with
executive functions such as
self-control,
planning,
reasoning, and
abstract thought. The area of the cerebral cortex devoted to
vision, the
visual cortex, is also greatly enlarged in humans compared to other animals.