Adult Brain, Normal

The Human Brain

The average adult brain weighs three pounds and controls all of the important functions in the body. The brain receives information through the five senses: sight, sound, touch, smell and taste. It uses this information to control processes like movement, memory, emotion, hunger and breathing, to name just a few. 

The brain is made of 60% fat. It also contains blood vessels, nerves and neurons. Together with the spinal cord, the brain makes up the central nervous system. The brain sends and receives chemical and electrical signals throughout the body. To do this, the central nervous system relies on a vast network of more than one billion nerve cells. 

Parts of the Brain 

The brain is enclosed by the skull and consists of three primary parts:

• Cerebrum: The largest part of the brain, which includes the left and right hemispheres. Responsible for memory, thinking, feeling and problem-solving. The surface of the cerebrum is called the cortex, the gray matter that gives the brain its wrinkled appearance.
• Cerebellum: Located under the cerebrum, the cerebellum controls muscle movements, balance and posture.
• Brainstem: Connecting the cerebrum and cerebellum to the spinal cord, the brainstem controls many processes including sleep, digestion, heart rate and body temperature.

Each hemisphere of the brain has four lobes: 

• Frontal lobe: Located in the front of the head, it plays a key role in personality, emotion, intelligence and planning. 
• Temporal lobe: Located on the sides of the brain, it’s responsible for short-term memory, speech and smell. 
• Parietal lobe: Located in the middle of the brain, it plays a role in speech recognition, spatial awareness and touch.
• Occipital lobe: Located at the back of the brain, it’s responsible for vision.

Other important structures in the brain include the hypothalamus, pituitary gland, amygdala and hippocampus. All parts of the brain are connected to each other with white matter, a dense network of nerve fibers that allows the brain to communicate.