The Brain

The brain is a highly complex structure that controls how you function and interact with your surroundings. The brain and spinal cord make up the central nervous system. (Read about "The Nervous System") The major portions of the brain, according to the National Institutes of Health (NIH) are:

• brainstem
• cerebellum
• limbic system
• diencephalon
• cerebrum
• meninges

At the lowest part of the brain, where the spinal cord connects, is what is called the brain stem. It is made up of the medulla and the pons. The brain stem is what controls those things we don't think about, things like our heartbeat and our breathing. It also plays a role in telling us when we are hungry and when it is time to sleep.

Located above and behind the brain stem, in the lower part of our skull, is the cerebellum. The cerebellum is responsible for voluntary muscle movements. It helps us keep our balance, walk and do any number of motor tasks.

Above the brain stem is what is called the limbic system. The main parts are the amygdala and the hippocampus. NIH says they are part of the early evolution of our brains. They are involved in basic emotions, especially ones that help us survive, like fear and anger. They are also involved in pleasure sensations. The amygdala and the hippocampus are also involved in the formation of memories.

Right near the limbic system is the diencephalon. The major parts here are the thalamus and the hypothalamus. The thalamus acts as an exchange point for the thinking part of the brain and the sensory signals from the rest of the body. It also works with the cerebellum to keep us standing. The hypothalamus plays a role in regulating hormones and other chemicals that affect many things, including our heart, blood pressure, breathing, even whether we blush or not. It has a direct affect on the pituitary gland. The hypothalamus and the pituitary gland are part of our endocrine system. (Read about "Endocrine System")

The largest part of the brain is the cerebrum, which lies over all the rest of the portions of the brain. The cerebrum is made up of two halves called the left and right hemispheres. Each half is divided up into lobes, which have specific functions. The four lobes of each hemisphere, according to NIH, are:

• Frontal - which is in the front top of our brain, deals with problem solving, planning and decisions. It also coordinates our voluntary movements, things like grabbing a knife and fork or even kissing our family.
• Parietal - which is more to the top middle and back of our brain. Its main job is to process sensory information. Is it hot or cold? Are we feeling pain?
• Occipital - is on the backside of our brain and is involved in how we see things with our eyes.
• Temporal - wraps around the lower portion of the brain. Is involved in hearing and smell and is also involved in memory, emotion and language.

The outer portion of the cerebrum is the gray matter, which is called the cerebral cortex. It is made up of unmyelinated nerve cells. It's the gray matter where we do our thinking. It's the part of your brain that is processing the information on this page as you read it.

Beneath the gray matter is white matter, which is made up of nerve fibers that are myelin coated and connect the cerebral cortex to everything else. Myelin insulates the nerve sheath, allowing impulses to travel much faster. Damage to myelin is associated with diseases such as multiple sclerosis. (Read about "Multiple Sclerosis")

Covering the entire brain and the spinal cord are the meninges. They consist of three layers. The outer layer is called the dura mater, the middle layer is the pia mater and the inner most layer is the arachnoid. Infection of the meninges is called meningitis. (Read about "Encephalitis & Meningitis")

Following the links below will give you more information on some conditions that affect the brain and nervous system, including mental health conditions.