Your brain is an essential organ that controls many body functions. Your brain receives and interprets all the sensory information you encounter, like sights, sounds, smells and tastes. Your brain has many complex parts that work together to help you function.
Your brain is an essential organ. All of your emotions, sensations, aspirations and everything that makes you uniquely individual come from your brain. This complex organ has many functions. It receives, processes and interprets information. Your brain also stores memories and controls your movements.
Your brain is one component of your central nervous system (CNS). It connects to your spinal cord, the other part of your CNS.
Your brain receives information from your five senses: sight, smell, sound, touch and taste. Your brain also receives inputs including touch, vibration, pain and temperature from the rest of your body as well as autonomic (involuntary) inputs from your organs. It interprets this information so you can understand and associate meaning with what goes on around you.
Your brain enables:
Your brain’s structure is complex. It has three main sections:
Each side of your brain has different lobes (sections). While all the lobes work together to ensure normal functioning, each lobe plays an important role in some specific brain and body functions:
Your cerebrum divides into two halves: the left and right cerebral hemispheres. The two halves of the brain are connected by nerve fiber bundles (white matter) called your corpus callosum. The right side of your cerebrum controls movement on the left side of your body and vice versa.
Your left brain hemisphere is often the “dominant” hemisphere — but this doesn’t apply to everyone. Most people who are right-handed are usually left hemisphere dominant. Some patients who are left-handed are right hemisphere is dominant. Typically, the dominant hemisphere is responsible for your speech and language functions. Your non-dominant (which is the right hemisphere in most individuals) is responsible for your spatial awareness and processing of what you see.
About 1 in 10 right-handed people and about 1 in 3 left-handed people have dominance in the right hemisphere. This means that their speech functions are mostly centered in the right side of their brains. Many times this is a normal variant but in some people with brain tumors or epilepsy, the dominance can be shifted through a process called brain plasticity.
A bony structure called your cranium surrounds your brain. Your cranium is part of your skull. All the bones of your skull protect your brain from injury.
Between your brain and skull, you have three layers of tissue called the meninges:
Between your arachnoid and pia mater tissue is a clear substance called your cerebrospinal fluid (CSF). CSF also surrounds your spinal cord, which runs through the vertebrae (bones of your spine). CSF cushions and protects these vital nervous system organs.
Substances called gray and white matter make up your central nervous system. In your brain, gray matter is the outermost layer. It plays a significant part in your day-to-day function.
White matter is your deeper brain tissue. It contains nerve fibers that help your brain send electric nerve signals more quickly and efficiently.
Your brain contains several types of nerves. Nerves carry messages by sending electrical impulses back and forth between your brain, organs and muscles. The nerves in your brain are called cranial nerves.You have 12 pairs of cranial nerves from the brain to parts of your head and face. These nerves are responsible for specific sensations, such as hearing, taste or sight. White matter is the fiber bundles that connect brain cells. There are numerous white matter tracts that connect one area of your brain to another, as well as structures deep in your brain. These white matter tracts can also travel to your brainstem and spinal cord so that information can be relayed from your brain to communicate with the rest of your body and information from your body can travel to your brain.
Although most brain cells reside on the surface of your brain (called gray matter) and the cabling (white matter) is deep and connects various parts of your brain, there are some nuclei (collection of brain cells) that reside deep in your brain. They include:
For many years, scientists thought the human brain had 100 billion nerve cells (neurons). Today, we know the actual number is closer to 86 billion.
Your brain contains two types of cells:
Within your thalamus sits a small structure called your hypothalamus. Your hypothalamus is part of your limbic system, which controls your emotions. It sends nerve signals to your pituitary gland. It helps control functions such as:
In your brain, you also have a pineal gland, which secretes the hormone melatonin. Melatonin controls how melanin gives your skin pigment. Melatonin also plays a role in regulating your sleep and wake cycles.
About 1 in 6 people have some type of brain condition. There are many types of brain disorders and conditions that vary in severity, including:
Some babies are born with a brain condition. Inherited conditions, genetic differences or injuries in the uterus or at birth can cause these conditions.
Rarely, severe brain injuries may lead to a condition like epilepsy or dementia. Many people heal from a concussion or brain injury. Repeated head injuries can lead to chronic traumatic encephalopathy (CTE), a condition that causes progressively worsening thinking problems.
Some lifestyle habits can keep your brain healthier. To support your brain health, you may:
A strong social network can also improve your brain health. Healthy relationships can help decrease stress, lower your blood pressure and increase your life span.
You may also want to ask your healthcare provider:
When you're born, your brain weighs about 1 pound. Throughout childhood, your brain grows to about 2 pounds. As an adult, your brain weighs around 2.7 to 3 pounds, depending on your sex and body size.
Most brain development happens between birth and your teenage years. But your brain continues developing throughout your 20s. Brain development typically peaks by middle age.
A note from Cleveland Clinic
Your brain is an essential organ that allows you to perceive and interact with the world around you. It receives and interprets all the sensory information you encounter. A range of conditions can affect your brain. You can support your brain health by sleeping well, eating a healthy diet, exercising and making other healthy lifestyle choices. If you suspect that you or a loved one has symptoms related to a brain condition, speak with a healthcare provider.
Last reviewed by a Cleveland Clinic medical professional on 03/30/2022.
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