The brain is the part of the central nervous system that lies within the skull. It weighs about three pounds and is a pinkish-gray mass composed of about 10 billion nerve cells that transmit electrochemical signals. The brain is responsible for controlling all mental functions and coordinating physical functions, including movement, sleep, hunger and thirst.
The bones of the skull and face are designed to protect the brain, provide structure for the face, and form the openings through which food, water, and air enter the body. The skull consists of 22 bones. Of these bones, eight surround and protect the brain (cranium), and the remaining 14 form the underlying structure of the face (mandible).
The largest part of the brain is called the cerebrum. It is the “thinking” part of the brain and controls all voluntary muscles. Both short-term and long-term memories reside here, and it is the cerebrum that helps us reason. The cerebrum is divided into two halves—right and left. The right half controls the left side of the body and the left half controls the right side of the body. There are also cells in the brain called amygdala, that control emotions.
The cerebellum is at the back side of the brain and is much smaller than the cerebrum. It controls balance, movement and coordination.
The brain stem sits beneath the cerebrum and in front of the cerebellum. It connects the brain to the spinal cord and controls our involuntary functions, such as breathing and telling the heart to pump blood throughout the body.
The pituitary gland and hypothalamus are two very small parts of the brain. The pituitary gland produces hormones that promote growth, play a role in puberty and regulate blood sugar. The hypothalamus controls the body’s temperature, telling the body to sweat if the temperature is too high and shiver if it’s too cold.
Because the brain is so complex, it requires specially-trained physicians to treat injuries and disorders.