The brain is an organ that’s made up of a large mass of nerve tissue that’s protected within the skull. It plays a role in just about every major body system.

Some of its main functions include:

  • processing sensory information
  • regulating blood pressure and breathing
  • releasing hormones

Use this interactive 3-D diagram to explore the brain.

Cerebrum

The cerebrum is the largest part of the brain. It’s divided into two halves, called hemispheres.

The two hemispheres are separated by a groove called the great longitudinal fissure. The corpus callosum connects the two hemispheres, thus allowing the brain to deliver messages from one side to the other.

Each hemisphere of the cerebrum is divided into broad regions called lobes. Each lobe is associated with different functions:

  • Frontal lobes. The frontal lobes are the largest of the lobes. As indicated by their name, they’re located in the front part of the brain. They coordinates high-level behaviors, such as motor skills, problem-solving, judgment, planning, and attention. The frontal lobes also manage emotions, personality, and temper.
  • Parietal lobes. The parietal lobes are located behind the frontal lobes. They’re involved in organizing and interpreting sensory information from other parts of the brain.
  • Temporal lobes. The temporal lobes house the auditory cortex. They are located on either side of the head on the same level as the ears. They coordinate specific functions, including hearing, visual memory (such as facial recognition), verbal memory (such as understanding language), and interpreting the emotions and reactions of others.
  • Occipital lobes. The occipital lobes are located in the back of the brain. They’re heavily involved in the ability to read and recognize colors and shapes.

Cerebellum

The cerebellum is located in the back of the brain, just below the occipital lobes. It’s involved with fine motor skills, which refers to the coordination of smaller, or finer, movements, especially those involving the hands and feet.

The cerebellum also helps the body maintain its posture, equilibrium, and balance.

Diencephalon

The diencephalon is located at the base of the brain. It contains the:

The thalamus acts as a kind of relay station for signals coming into the brain. It’s also involved in alertness, pain sensations, and attention.

The epithalamus serves as a connection between the limbic system and other parts of the brain. The limbic system is a part of the brain that’s involved with emotion.

The hypothalamus processes information that comes from the autonomic nervous system. Its role includes controlling eating, sleeping, and sexual behavior. Some specific actions the hypothalamus is responsible for include:

  • maintaining daily physiological cycles, such as the sleep-wake cycle
  • controlling appetite
  • regulating body temperature
  • controlling the production and release of hormones

Brain stem

The brain stem is located in front of the cerebellum and connects to the spinal cord. It’s responsible for passing messages to various parts of the body and the cerebral cortex. It consists of three major parts:

  • Midbrain. The midbrain helps control eye movement, processes visual and auditory information, regulates motor movements, and is involved in arousal and wakefulness.
  • Pons. This is the largest part of the brain stem. It’s located below the midbrain. It’s a group of nerves that help connect different parts of the brain. The pons also contains the start of some of the cranial nerves. These nerves are involved in facial movements and transmitting sensory information, as well as breathing.
  • Medulla oblongata. The medulla oblongata is the lowest part of the brain. It acts as the connection between the brain stem and spinal cord. It also acts as the control center for the function of the heart and lungs. It helps regulate many important functions, including motor and sensory functions, breathing, sneezing, and swallowing.

There are hundreds of conditions that can affect the brain. Most of them fall within 1 of 5 main categories:

Learn more about the different types of brain conditions.

The brain is one of your most important body parts, so it’s important to know how to recognize signs that there may be a problem.

Brain injury symptoms

Brain injury symptoms depend on the type and severity of the injury. While they sometimes appear immediately after a traumatic event, they can also show up hours or days later.

General brain injury symptoms may include:

  • headache
  • nausea or vomiting
  • feeling confused or disoriented
  • dizziness
  • feeling tired or drowsy
  • speech problems, including slurring
  • sleeping more or less than usual
  • dilation of one or both pupils
  • inappropriate emotional responses
  • seizures
  • sensory problems, such as blurry vision or a ringing in your ears
  • trouble remembering things or difficulty concentrating
  • extreme mood changes or unusual behavior

Cerebrovascular injury symptoms

Symptoms tend to come on suddenly and include:

  • severe headache
  • loss of vision
  • inability to speak
  • inability to move or feel a part of the body
  • drooping face
  • coma

Brain tumor symptoms

Brain tumor symptoms depend on the size, location, and type of tumor.

General brain tumor symptoms may include:

  • headache
  • nausea or vomiting
  • loss of motor coordination, such as trouble walking
  • feeling sleepy
  • feelings of weakness
  • appetite changes
  • convulsions or seizures
  • issues with your vision, hearing, or speech
  • difficulty concentrating
  • extreme mood changes or behavior changes

Neurodegenerative symptoms

Neurodegenerative diseases cause damage to nervous tissue over time, so their symptoms may get worse as time goes on.

General neurodegenerative symptoms include:

  • memory loss or forgetfulness
  • changes in mood, personality, or behavior
  • issues with motor coordination, such as difficulty walking or staying balanced
  • speech issues, such as slurring or hesitation before speaking

Psychological symptoms

Symptoms of psychological, or mental health, conditions can be very different from person to person, even when they involve the same condition.

Some general symptoms of a mental health condition include:

  • excessive feelings of fear, worry, or guilt
  • feeling sad or dejected
  • confusion
  • difficulty concentrating
  • low energy
  • extreme stress that gets in the way of daily activities
  • extreme mood changes
  • withdrawal from loved ones or activities
  • delusions or hallucinations
  • suicidal ideation

Some brain conditions may be outside your control, like trauma to the brain or mental health issues.

But there are things you can control and do to help keep your brain in good health, and to reduce your risk of certain health conditions.

Protect your head

Always wear a helmet when playing contact sports or riding a bike. Be sure to buckle up when you get in the car. Both of these can go a long way when it comes to avoiding brain injuries.

Exercise

Doing regular cardio workouts stimulates blood flow throughout your body, including your brain. It can also improve brain health in a variety of ways, including:

  • improved emotional health
  • improved learning ability
  • reduced anxiety
  • reduced cognitive decline

Quit smoking

Smoking isn’t great for your overall health. That includes your brain: Smoking may lead to cognitive decline.

Listen to your thoughts

Try to check in from time to time with your thoughts or feelings. Keeping a diary is a good way to get into this habit. Look for any thought patterns or emotions that seem to be impacting your day-to-day life. They could be a sign of an underlying, treatable mental health condition.

Focus on a nutritious diet

What you eat can have a direct impact on the health of your brain, especially as you age. Many of the foods that are often recommended for brain health include lots of greens, fruits, nuts, fish, whole grains, olive oil and, occasionally, wine.