The brain is an organ located in the skull. It weighs about 3 pounds. The senses (taste, smell, sight, hearing, touch), emotions, thoughts, and movement are controlled by the brain. The right side of the brain controls the left side of the body and the left side of the brain controls the right side of the body.
There are three main parts of the brain: the cerebrum, cerebellum, and brain stem. (Brain diagram compliments of UW Department of Neurosurgery, Janet Schukar)
Cerebrum controls higher brain functions and has four lobes, each with different functions:
- Frontal lobe: executive function, decisions, personality, language, planning, movement
- Parietal lobe: intelligence, reasoning, sensation, reading
- Occipital lobe: vision
- Temporal lobe: language, behavior, hearing, vision, emotions, memory
Cerebellum controls balance, coordination, and fine muscle control.
Brain Stem controls things we do without thinking, like our heartbeat, breathing, and swallowing. Click here for an interactive tour of the brain and its functions.
The Spinal Cord starts at the brain stem and goes to the tail bone. It is about as wide as your little finger and extends the length of your back. Messages are carried from the spinal cord to and from the brain to the rest of the body.
Spinal cord image reprinted by permission from Macmillan Publishers Ltd: Nature Publishing Group: Nature Reviews Neuroscience (Spinal cord repair strategies: why do they work?), copyright 2006.
Nerves extend from the spinal cord on each side and go to the parts of the body.
The brain and spinal cord are protected by bony structures: the skull and spinal column.
Meninges are membranes that cover and protect the brain and spinal cord.
There are three layers of meninges: Dura mater (closest to the bone), Arachnoid loosely around the brain, Pia mater is closely attached to the brain and spinal cord surface.
Cerebrospinal Fluid (CSF) cushions the brain and spinal cord. It is a clear, water-like fluid, also called spinal fluid, found between the arachnoid and pia mater. It is made within the four ventricles of the brain. The area in the lateral ventricles that makes spinal fluid is called the choroid plexus. About 20cc of spinal fluid is made but not absorbed each hour. There is about 140 cc (about ½ can of soda) of spinal fluid that surrounds the brain and spine. The brain and spinal cord are bathed and cushioned by this spinal fluid, which flows and circulates around the brain and spine.
(Image courtesy of American Brain Tumor Association)