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Anatomy of the Brain

By Olivia Guy-Evans, published Aug 26, 2021


The brain receives information from sensory receptors and sends messages to muscles and glands. It is the centre of all conscious awareness and is divided into different lobes with different functions. It contains the cerebrum which makes up about 85% of the total mass.

The brain controls all functions of the body, and interprets information from the outside world, and defines who we are as individuals and how we experience the world.

The brain receives information through our senses: sight, touch, taste, smell, and hearing. This information is processed in the brain, allowing us to give meaning to the input it receives.

The brain is part of the central nervous system (CNS) along with the spinal cord. There is also a peripheral nervous system (PNS) which is comprised of

The PNS is made up of 31 pairs of spinal nerves that branch from the spinal cord, and cranial nerves that branch from the brain.


Brain Parts

The brain is composed of the cerebrum, cerebellum, and brainstem (Fig. 1).

The brain is composed of the cerebrum, cerebellum, and brainstem

Figure 1. The brain has three main parts: the cerebrum, cerebellum and brainstem.

Cerebrum: is the largest and most recognisable part of the brain. It consists of grey matter (the cerebral cortex) and white matter at the centre. The cerebrum is divided into two hemispheres, the left and right, and contains the lobes of the brain (frontal, temporal, parietal, and occipital lobes). The cerebrum produces higher functioning roles such as thinking, learning, memory, language, emotion, movement, and perception.

Cerebellum: is located under the cerebrum and is responsible for monitoring and regulating motor behaviours, especially automatic movements. This structure is also important for regulating posture and balance, as well as recently being suggested for being involved in learning and attention. Although the cerebellum only account for roughly 10% of the brain’s total weight, this area is thought to contain more neurons (nerve cells) than the rest of the brain combined.

Brainstem: is located at the base of the brain. This area connects the cerebrum and the cerebellum to the spinal cord, acting as a relay station for these areas. The brainstem works by regulating automatic functions such as sleep cycles, breathing, body temperature, digestion, coughing, and sneezing.


Right Brain – Left Brain

The cerebrum is divided into two halves: the right and left hemispheres (Fig. 2). The left hemisphere controls the right half of the body, and the right hemisphere controls the left half of the body.

The two hemispheres are connected by a thick band of neural fibers known as the corpus callosum, consisting of about 200 million axons. The corpus callosum allows the two hemispheres to communicate with each other and allows for information being processed on one side of the brain to be shared with the other side.

The cerebrum is divided into left and right hemispheres. The two sides are connected by the nerve fibers corpus callosum.

Figure 2. The cerebrum is divided into left and right hemispheres. The two sides are connected by the nerve fibers corpus callosum.

Hemispheric lateralization is the idea that each hemisphere is responsible for different functions. Each of these functions are localized to either the right or left side.

The left hemisphere is associated with language functions, such as formulating grammar and vocabulary, and containing different language centres (Broca’s and Wernicke’s area).

The right hemisphere is associated with more visuospatial functions such as visualization, depth perception, and spatial navigation. These left and right functions are the case in the majority of people, especially those who are right-handed.


Lobes of the Brain

Each cerebral hemisphere can be subdivided into four lobes, each associated with different functions.

The four lobes of the brain are the frontal, parietal, temporal, and occipital lobes (Figure 3).

cerebral hemispheres: Frontal lobes, Occipital lobes, Parietal lobes, Temporal lobes

Figure 3. The cerebrum is divided into four lobes: frontal, parietal, occipital and temporal.

Frontal lobes

The frontal lobes are located at the front of the brain, behind the forehead (Figure 4). Their main functions are associated with higher cognitive functions, including problem-solving, decision-making, attention, intelligence, and voluntary behaviours.

The frontal lobes contain the motor cortex, which is responsible for planning and coordinating movements.

It also contains the prefrontal cortex, which is responsible for initiating higher-lever cognitive functioning, and Broca’s Area, which is essential for language production.

frontal lobe structure

Figure 4. Frontal lobe structure.

Temporal lobes

The temporal lobes are located on both sides of the brain, near the temples of the head, hence the name temporal lobes (Figure 5). The main functions of these lobes include understanding, language, memory acquisition, face recognition, object recognition, perception, and processing auditory information.

There is a temporal lobe in both the left and right hemispheres. The left temporal lobe, which is usually the most dominant in people is associated with language, learning, memorising, forming words, and remembering verbal information.

The left lobe also contains an important language centre known as Wernicke’s area, which is essential for language development. The right temporal lobe is usually associated with learning and memorising non-verbal information and determining facial expressions.

temporal lobe structure

Figure 5. Temporal lobe structure.

Parietal lobes

The parietal lobe is located at the top of the brain, between the frontal and occipital lobes, above the temporal lobes (Figure 6).

The parietal lobe is essential for integrating information from the body’s senses in order to allow us to build a coherent picture of the world around us.

These lobes allow us to have a perception of our bodies through somatosensory information (e.g. through touch, pressure, and temperature). It can also help with visuospatial processing, reading, and number representations (mathematics).

The parietal lobes also contain the somatosensory cortex, which receives and processes sensory information, integrating this into a representational map of the body.

This means it can pinpoint the exact area of the body where sensation is felt, as well as being able to perceive the weight of objects, shape, and texture.

Parietal Lobe Structure (Simply Psychology)

Figure 6. Parietal lobe structure.

Occipital lobes

The occipital lobes are located at the back of the brain behind the temporal and parietal lobes and below the occipital bone of the skull (Figure 7).

The occipital lobes receive sensory information from the retinas of the eyes which is then encoded into different visual data. Some of the functions of the occipital lobes include being able to assess size, depth, and distance, determine colour information, object and facial recognition, and mapping the visual world.

The occipital lobes also contain the primary visual cortex which receives sensory information from the retinas, transmitting this information relating to location, spatial data, motion, and the colours of objects in the field of vision.

Occipital Lobe Structure (Simply Psychology)

Figure 7. Occipital lobe structure.


Cerebral Cortex

The surface of the cerebrum is called the cerebral cortex, and has a wrinkled appearance, consisting of bulges, also known as gyri, and deep furrows, known as sulci (Figure 8).

A gyrus (plural: gyri) is the name given to the bumps ridges on the cerebral cortex (the outermost layer of the brain). A sulcus (plural: sulci) is another name for a groove in the cerebral cortex.

The cortex contains neurons (grey matter), which are interconnected to other brain areas by axons (white matter). The cortex has a folded appearance. A fold is called a gyrus and the valley between is a sulcus.

Figure 8. The cortex contains neurons (grey matter), which are interconnected to other brain areas by axons (white matter). The cortex has a folded appearance. A fold is called a gyrus and the valley between is a sulcus.

The cerebral cortex is primarily constructed of grey matter (neural tissue that is made up of neurons), with between 14 and 16 billion neurons being found here.

The many folds and wrinkles of the cerebral cortex allow for a wider surface area for an increased number of neurons to live there, permitting large amounts of information to be processed.


Deep Structures

Amygdala

The amygdala is a structure deep in the brain which is involved in the processing of emotions, and fear-learning. The amygdala is a part of the limbic system, a neural network which mediates emotion and memory (Figure 9).

This structure is also involved in tying emotional meaning to memories, processes rewards, and helps us make decisions. This structure has also been linked with the fight-or flight response.

The amygdala in the limbic system plays a key role in how animals assess and respond to environmental threats and challenges by 
evaluating the emotional importance of sensory information and prompting an appropriate response.

Figure 9. The amygdala in the limbic system plays a key role in how animals assess and respond to environmental threats and challenges by evaluating the emotional importance of sensory information and prompting an appropriate response.

Thalamus and Hypothalamus

The thalamus is involved in relaying information between the cerebral cortex and the brain stem, and within other cortical structures (Figure 10).

Because of its interactive role in relaying sensory and motor information, the thalamus contributes to many processes including attention, perception, timing, and movement. The hypothalamus modulates a range of behavioural and physiological functions.

It controls autonomic functions such as hunger, thirst, body temperature, and sexual activity. In order to do this, the hypothalamus integrates information from different parts of the brain and is responsive to a variety of stimuli such as light, odour, and stress.

The thalamus is often described as the relay station of the brain as a great deal of information that reaches the cerebral cortex, first stops in the thalamus before being sent to its destination.

Figure 10. The thalamus is often described as the relay station of the brain as a great deal of information that reaches the cerebral cortex, first stops in the thalamus before being sent to its destination.

Hippocampus

The hippocampus is a curved-shaped structure in the limbic system which is associated with learning and memory (Figure 11).

This structure is most strongly associated with the formation of memories, is an early storage system for new long-term memories, and plays a role in the transition of these long-term memories to more permanent memories.

Hippocampus location in the brain

Figure 11. Hippocampus location in the brain">

Basal ganglia

The basal ganglia are a group of structures which regulate the coordination of fine motor movements, balance, and posture, alongside the cerebellum.

These structures are connected to other motor areas and link the thalamus with the motor cortex. The basal ganglia are also involved in cognitive and emotional behaviours, as well as playing a role in reward and addiction.

Ventricles and cerebrospinal fluid

Within the brain there are fluid-filled interconnected cavities which are extensions of the spinal cord, called ventricles. These are filled with a substance called cerebrospinal fluid, which is a clear and colourless liquid.

The ventricles produce cerebrospinal fluid and transport as well as remove this fluid. The ventricles do not have a unique function, but it provides cushioning to the brain and is useful for determining the locations of other brain structures.

Cerebrospinal fluid circulates the brain and spinal cord and functions to cushion the brain within the skull. If damage occurs to the skull, the cerebrospinal fluid will act as a shock absorber to help protect the brain from injury.

As well as providing cushioning, the cerebrospinal fluid works to circulate nutrients and chemical filtered from the blood, as well as removing waste products from the brain. cerebrospinal fluid is constantly being absorbed and replenished by the ventricles. If there were a disruption or blockage, this can cause a build up of cerebrospinal fluid and can cause enlarged ventricles.


Neurons

Neurons Neurons are the nerve cells of the central nervous system that transmit information through electrochemical signals throughout the body. Neurons contain a soma, which is a cell body, from which the axon extends. Axons are nerve fibres which are the longest part of the neuron, which conducts electrical impulses away from the soma.

Neuron (Nerve Cells) Structure

There are dendrites at the end of the neuron, which are branch-like structures that can send and receive information from other neurons. There is also myelin sheath, which is a fatty insulating layer that forms around the axon, allowing nerve impulses to travel down the axon quickly. There are different types of neurons. Sensory neurons transmit sensory information, motor neurons transmit motor information, and relay neurons allow sensory and motor neurons to communicate to each other.

The communication between neurons is called synapses. Neurons communicate with each other via synaptic clefts, which are gaps between the endings of neurons. During synaptic transmission, chemicals, such as neurotransmitters are released from the endings of the previous neuron (also known as the presynaptic neuron).

These chemicals enter the synaptic cleft to then be transported to receptors on the next neuron (also known as the postsynaptic neuron). Once transported to the next neuron, the chemical messengers continue travelling down neurons in order to influence many functions such as behaviour and movement.


Glial cells

Glial cells are non-neuronal cells in the central nervous system which work to provide the neurons with nourishment, support, and protection.

Astrocytes

These are star-shaped cells which function to maintain the environment for neuronal signalling, through controlling the levels of neurotransmitters surrounding the synapses. They also work to clean up what is left behind after synaptic transmission, either recycling any leftover neurotransmitter or cleaning up when a neuron dies.

Oligodendrocytes

These types of glial have the appearance of balls with spikes all around them. They function by wrapped around the axons of neurons to form a protective layer call myelin sheath. This is a substance which is rich in fat and provides insulation to the neurons to aid neuronal signalling.

Microglial

Microglial are small cells with oval bodies and many branches projecting out of them. The main function of these cells is to respond to injuries or disease in the central nervous system. They respond by either clearing away any dead cells or remove any harmful toxins or pathogens that may be present, so are therefore important to the health of the brain.

Ependymal cells

These types of cells are column shaped and usually line up together to form a membrane, called the ependyma. The ependyma is a thin membrane lining the spinal cord and ventricles of the brain. in the ventricles, these cells have small hairlike structures on them called cilia, which help encourage the flow of cerebrospinal fluid.

Cranial Nerves

There are 12 types of cranial nerves which are linked directly to the brain without having to pass through the spinal cord. These allow sensory information to pass from the organs of the face to the brain:

Mnemonic for Order of Cranial Nerves:

Some Say Marry Money But My Brother Says Big Brains Matter More

  1. Cranial I: Sensory
  2. Cranial II: Sensory
  3. Cranial III: Motor
  4. Cranial IV: Motor
  5. Cranial V: Both (sensory & motor)
  6. Cranial VI: Motor
  7. Cranial VII: Both (sensory & motor)
  8. Cranial VIII: Sensory
  9. Cranial IX: Both (sensory & motor)
  10. Cranial X: Both (sensory & motor)
  11. Cranial XI: Motor
  12. Cranial XII: Motor

About the Author

Olivia Guy-Evans obtained her undergraduate degree in Educational Psychology at Edge Hill University in 2015. She then received her master’s degree in Psychology of Education from the University of Bristol in 2019. Olivia has been working as a support worker for adults with learning disabilities in Bristol for the last four years.

How to reference this article:

Guy-Evans, O. (2021, Aug 26). Anatomy of the brain . Simply Psychology. https://www.simplypsychology.org/Anatomy-of-the-Brain.html

APA Style References

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Mayfield Brain and Spine (n.d.). Anatomy of the Brain. Retrieved July 28, 2021, from: https://mayfieldclinic.com/pe-anatbrain.htm

Robertson, S. (2018, August 23). What is Grey Matter? News Medical Life Sciences. https://www.news-medical.net/health/What-is-Grey-Matter.aspx

Guy-Evans, O. (2021, April 13). Temporal lobe: definition, functions, and location. Simply Psychology. https://www.simplypsychology.org/temporal-lobe.html

Guy-Evans, O. (2021, April 15). Parietal lobe: definition, functions, and location. Simply Psychology. https://www.simplypsychology.org/parietal-lobe.html

Guy-Evans, O. (2021, April 19). Occipital lobe: definition, functions, and location. Simply Psychology. https://www.simplypsychology.org/occipital-lobe.html

Guy-Evans, O. (2021, May 08). Frontal lobe function, location in brain, damage, more. Simply Psychology. https://www.simplypsychology.org/frontal-lobe.html

Guy-Evans, O. (2021, June 09). Gyri and sulci of the brain. Simply Psychology. https://www.simplypsychology.org/gyri-and-sulci-of-the-brain.html

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