What is Inside the Brain?

Our brain is known to be the most powerful organ. Its texture is similar to a firm jelly and weighs about only three pounds. This article answers the question “What is Inside the Brain?” It discusses in detail the various parts that make up the brain as well as their functions. The article answers some frequently asked questions in the end.

What is Inside the Brain?

Our bodies’ richest networks of blood vessels are used to nourish our bodies. When involved in a complex thought process the brain uses up to 50% of the body’s oxygen and fuel. 

With each heartbeat, our arteries carry up to 20-25% of the blood to the brain. The whole blood vessel network comprises capillaries and veins along with the arteries. In this process around a billion cells use   20% of the fuel and oxygen that the blood vessel is capable of carrying. 

What is the grey matter and white matter?

The central nervous system is comprised of two different brain regions. The Gray matter and the white matter. In brain regions, the grey matter is the darker, outer region of the brain, while the white matter is the inner lighter region of the brain. 

However, in the spinal cord, the order is opposite this. In the spinal cord, the grey matter is the inner region and the white matter is the outer region of the brain. 

In the brain, the grey matter is composed of something known as somas, which are the central round cell bodies, whereas the white matter is made of long stems known as axons, which are responsible for connecting different neurons to one another. Axons are wrapped in myelin which is the protective coating. Under certain scans, the different compositions of neurons clearly distinguish the two as separate shades. 

Which are the main Parts of the Brain?

The brain is classified into three main parts or areas of the brain:

Cerebrum: 

This is the front part of the brain is comprised of the grey matter- the cerebral cortex and white matter at the centre. 

The cerebrum is the largest part of the brain, this part is responsible for the regulation of the temperature of the body as well as for coordinating movements of the body. 

The cerebrum enables thinking, reasoning, problem-solving, speech, judgement, learning and regulating emotions. There are other functions of the brain, and these are related to vision, touch and hearing. 

Cerebral Cortex

The cortex is come from the Latin word “bark” and is used to describe the outer grey matter that covers the cerebrum. This part has a larger surface, this is because this area has folds and comprises half of the brain weight.  One region of the cortex is covered by ridges (gyri) and other folds (sulci). 

These two parts join at the deep large sulcus, this is the interhemispheric fissure, AKA the medial longitudinal fissure that runs from the front part of the head to the back part. The left hemisphere of the brain controls the right side of the body, and the right hemisphere controls the left side of the body. 

These two halves of the brain communicate through a C- type large structure known as the corpus callosum. This is located in the centre of the cerebrum. The corpus callosum comprises nerve pathways and white matter. 

Brainstem

This connects the cerebrum with the spinal cord and forms the middle part of the brain. The brainstem comprises the midbrain, pons and medulla. 

Midbrain

The midbrain (or mesencephalon), has a range of different neuron clusters (nuclei and colliculi) is a very complex structure and has several neural pathways and other structures. 

The midbrain coordinates various functions, these functions range from hearing and movement, they also help in calculating different responses and changes in the environment.

The midbrain also contains the substantia nigra, this part is affected by Parkinson’s disease. This part is rich in dopamine neurons and also is part of the basal ganglia, this part of the brain helps in enabling movement and coordination.

Pons

The pons is derived from the Latin word “bridge”. Pons connect the midbrain and the medulla. These are the origin of four of the 12 cranial nerves, these help enable a range of activities such as tear production, chewing, blinking, focusing vision, balance, hearing and facial expression. 

Medulla

This is located at the bottom of the brainstem, the medulla is where the brain meets the spinal cord. This plays an important role in survival. The medulla helps produce reflexive activities such as sneezing, vomiting, coughing and swallowing. 

The medulla has other important functions such as regulating many bodily activities, including heart rhythm, breathing, blood flow, and oxygen and carbon dioxide levels.

The spinal cord extends itself from the bottom part of the medulla through the large opening in the skull. The spinal cord carries important messages from the brain to the rest of the body, through the vertebrae. 

Cerebellum

The cerebellum is also known as the (“little brain”) and is a fist-sized portion of the brain. The cerebellum just like the cerebral cortex has two hemispheres. The outer portion contains neurons, and the inner area communicates with the cerebral cortex. This has two hemispheres, the inner part communicates with the cerebral cortex, whereas the outer part contains neurons. 

The function of the cerebellum is to help coordinate voluntary muscle movements, balance, posture and maintain equilibrium  (Strick et al., 2009). 

Several recent studies are understanding the possible involvement in addiction, autism and schizophrenia. Studies are also exploring the role of the cerebellum in regulating thoughts, emotions and social behaviour. 

Deeper Structures Within the Brain

Pituitary Gland

This is located deep behind the bridge of the nose and is a pea-sized structure. The hypothalamus sends chemical signals to the pituitary gland, through its blood supply and stock.  

Hypothalamus

Located right below the pituitary gland is the hypothalamus. the hypothalamus is responsible for regulating hunger, body temperature and sleep patterns. This is also responsible for controlling some aspects of emotion and memory.  

Amygdala

This is a small almond-shaped structure. Amygdala is a part of the limbic system and regulates part of memory and emotion. This is located right under half (hemisphere) of the brain. The amygdala regulates the body’s “fight or flight” response when the brain perceives a threat. 

Hippocampus

Part of the larger structure called the hippocampal formation is the hippocampus. This is a curved seahorse-shaped organ which is located on the underside of each temporal lobe. The hippocampus receives information from the cerebral cortex and plays an important role in learning, memory, perception of space and navigation. 

Pineal Gland

Located deep in the brain and attached by a stalk to the top of the third ventricle is the pineal gland. The pineal gland helps regulates the sleep-wake cycle and circadian rhythms. The pineal gland secretes melatonin which helps in the function and plays an important role in the regulation of light and dark. 

Cranial Nerves

There are 12 nerves, inside the cranium (the dome of the skull) they are  called cranial nerves:

Cranial nerve 1: This is known as the olfactory nerve, this helps process information related to the sense of smell.

Cranial nerve 2: This is known as the optic nerve and governs eyesight.

Cranial nerve 3: The oculomotor nerve It branches out from the area in the brainstem where the midbrain meets the pons and controls motions of the eyes and pupil response. 

Cranial nerve 4: The trochlear nerve emerges from the back of the midbrain part of the brainstem and controls various muscles in the eye. 

Cranial nerve 5: The trigeminal nerve originates from the pons and conveys sensation from the scalp, teeth, jaw, sinuses, parts of the mouth and face to the brain, it allows the function of chewing muscles, and much more. This is the largest and most complex of the cranial nerves, with motor and sensory functions. 

Cranial nerve 6: The abducens nerve innervates some of the muscles in the eye.

Cranial nerve 7: The facial nerve supports glandular,  face movement, taste, and other functions.

Cranial nerve 8: The vestibulocochlear nerve helps facilitate hearing and balance of the body.

Cranial nerve 9: The glossopharyngeal nerve allows throat, ear and taste movements this has many more functions.

Cranial nerve 10: The Vagus nerve allows sensation around the digestive system ear and controls motor activity in the throat, digestive system and heart. 

Cranial nerve 11: The accessory nerve innervates specific muscles in the neck, head, and shoulder.

Cranial nerve 12: The hypoglossal nerve controls the motor activity of the tongue.

The first two nerves of the brain region originate in the cerebrum, and the remaining 10 cranial nerves emerge from the area of the brainstem. This region has three parts: the midbrain, the pons and the medulla.

Lobes of the Brain and What They Control 

The cerebrum has four hemispheres, each of these has four sections also known as lobes, each of these lobes control different specific functions. 

The four lobes are known as the frontal lobe, parietal lobe, temporal lobe and occipital lobe (Casillo et al., 2020).

Frontal lobe

This is located in the front part of the brain and is the largest lobe of the brain. The frontal lobe is involved in the movement, decision making and personality characteristics. Broca’s area is located in the frontal lobe and is associated with speech ability. Part of the role of the frontal lobe is to partially recognize smells. 

Parietal lobe

This part of the lobe helps individuals understand spatial relationships and identify objects. This is located in the middle part of the brain. This is located in the Wernicke’s area, which helps the brain understand spoken language. The parietal lobe helps in interpreting touch and processing pain in the body. 

Occipital lobe

The occipital lobe is located in the back part of the brain and helps process visual information. 

Temporal lobe

This part of the brain is involved in short-term memory, musical rhythm, speech, and some proportion of smell recognition.

Conclusion

This article answered the question “What is Inside the Brain?” It discussed in detail the various parts that make up the brain as well as their functions. The article answers some frequently asked questions in the end.

Frequently Asked Questions: What is Inside the Brain?

Does the brain work 24 hours?

Brains can work 24 hours a day with no rest.

Does the brain sleep?

Sleep is one of the most crucial aspects of brain functioning. Sleep also plays an important role in how neurons communicate with one another. Findings suggest that sleep also plays an important role in taking out the toxins in your brain and renovating thought processes when one is awake. 

Is the brain capable of healing itself?

Yes. In fact, the process known as neuroplasticity plays an important role in carrying out the function and making the brain resilient. The brain repairs itself through the process of neuroplasticity. 

References

Casillo, S. M., Luy, D. D., & Goldschmidt, E. (2020). A History of the Lobes of the Brain. World Neurosurgery, 134, 353-360.

Strick, P. L., Dum, R. P., & Fiez, J. A. (2009). Cerebellum and nonmotor function. Annual review of neuroscience, 32(1), 413-434.