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Left & Right Hemispheres of the Brain

Melissa Bialowas, Artem Cheprasov
  • Author
    Melissa Bialowas

    Melissa Bialowas has taught preschool through high school for over 20 years. She specializes in math, science, gifted and talented, and special education. She has a Master's Degree in Education from Western Governor's University and a Bachelor's Degree in Sociology from Southern Methodist University. She is a certified teacher in Texas as well as a trainer and mentor throughout the United States.

  • Instructor
    Artem Cheprasov

    Artem has a doctor of veterinary medicine degree.

Learn about the left and right hemispheres of the brain and how they work together. Identify what connects the left and right hemispheres of the brain. Updated: 10/20/2021

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Sides of the Brain

The human brain has three major parts: the brainstem, the cerebellum, and the cerebrum. The brainstem connects the brain to the spinal cord and performs the basic functions of the human body including breathing, swallowing, heart beating, and regulating body temperature. These are all automatic functions because of the brainstem. The cerebellum is at the back underside of the brain and controls muscle movements, balance, and posture.

In this diagram the eye is on the left side. The brain stem is sticking out of the bottom ready to connect to the spinal cord. The cerebellum is the part with stripes near the back of the brain.

Human Brain, Cerebellum, Brain Stem, Cerebrum

The majority of the brain is made of the cerebrum. This part of the brain is responsible for interpreting the senses, speech, reasoning, emotion, learning, and more. The cerebrum is divided into two hemispheres. These are conveniently called the right hemisphere and the left hemisphere. The two hemispheres are the same size, but perform different functions. Each of the hemispheres is divided into four different lobes: frontal, parietal, occipital, and temporal. The outer layer of the cerebrum is called the cerebral cortex or the cerebral mantle. Between the two hemispheres there is a deep groove called the longitudinal fissure. The two hemispheres are connected by a band of nerve fibers called the corpus callosum.

This view of the brain displays the two hemispheres of the cerebrum.

Brain, Hemispheres

The brain has two different types of matter. They are named for their colors. Gray matter appears a light gray color and it contains most of the neuronal cell bodies. This portion is responsible for muscle control, sensory perception, decision making, learning, and self-control among many other functions. It makes up the majority of the cerebral cortex. White matter in the brain appears white because it is covered in a waxy substance called myelin. This portion is responsible for relaying and coordinating messages and information from one area of the brain and spinal cord to another.

This diagram shows the white and gray matter in one hemisphere of the brain.

Brain, White and Gray Matter

What Connects the Left and Right Hemispheres of the Brain?

The two hemispheres are connected with white matter in a band of nerve fibers called the corpus callosum. These nerves help the two hemispheres communicate with each other. Each side of the brain controls the opposite side of the body. For example, the right side of the brain controls the left side of the body and vise versa. There have been studies of people with brain damage due to accidents or strokes in order to better understand which portions of the brain are responsible for certain types of thinking. In the 1960s it was discovered that one type of epilepsy could be treated by splitting the brain, that is cutting the connection between the two hemispheres.

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The corpus callosum, in yellow, connects the two hemispheres of the brain. This must be cut, causing a split-brain, to treat some illnesses.

Corpus Callosum

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Frequently Asked Questions

What is the difference between right and left brain?

The left brain is stronger at processing language and the right brain is stronger at processing emotion. However they both can perform all of the functions normally associated with the other side.

What sides of your brain control what?

The left side of the brain controls the movement of the right side of the body. The right side of the brain controls the movement of the left side of the body.

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