Table of Contents
General Makeup of Brain
The brain is a part of the central nervous system of the human body.[1]https://www.nichd.nih.gov/health/topics/neuro/conditioninfo/parts The brain is 60% fat which makes 50% of the dry weight of the brain.[2]https://pubmed.ncbi.nlm.nih.gov/20329590/[3]https://journals.sagepub.com/doi/pdf/10.1177/070674370304800308
Proteins, carbohydrates, water, and salts make the other 40% and weigh around 3 pounds. The brain is not a muscle but a collection of neural tissues.
General Functions of the Brain
The brain receives sensory inputs from the whole body, compares them, and generates motor outputs.
The brain controls memory, touch, vision, thought, emotions, motor skills, breathing, temperature, hunger, smell, basically everything that contributes to regulating the human body.
Main Divisions of The Brain
The brain has three main divisions: the forebrain, midbrain, and hindbrain.[4]https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Know-Your-Brain
Each of these divisions is further divided into functional parts that bring about the overall activity of the brain.
Forebrain
The forebrain makes the largest division of the three. It is also called prosencephalon as it develops from it in prenatal life.[5]https://www.sciencedirect.com/topics/neuroscience/prosencephalon
The prosencephalon further divides into telencephalon and diencephalon.
The telencephalon gives rise to the cerebral cortex whereas the diencephalon forms the deep structures of the forebrain such as the thalamus and the hypothalamus.
Parts of Forebrain
The forebrain is further divided into three main parts: the cerebrum, thalamus, and hypothalamus.[6]https://qbi.uq.edu.au/brain/brain-anatomy/forebrain Each of them is discussed below.
Cerebrum
The cerebrum is the front part of the brain and is composed of the right and left hemispheres. Each hemisphere has an outer cerebral cortex. Basal ganglia are present deep to the cortex in each hemisphere.
Basal Ganglia
These are a group of nuclei situated deep in the cerebral cortex. These nuclei include putamen and globus pallidus, collectively called the lentiform nucleus, caudate, substantia nigra, and subthalamic nuclei.
All of these are concerned with motor control, motor learning, emotions, behavior, and executive functions.[7]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3543080/
Cerebral Cortex
The cerebral cortex has multiple folds thus, it has a large surface area.
The cerebral cortex makes 50% of the total weight of the brain.
The cerebral cortex has lobes that are specialized in their specific functions.
- Frontal lobe: This lobe is involved in personality, memory, motor functions, language, and other cognitive functions.[8]https://www.neuroskills.com/brain-injury/frontal-lobes/
- Parietal lobe: This lobe is concerned with hearing, taste, touch, smell and vision.[9]https://www.spinalcord.com/parietal-lobe/
- Temporal lobe: This is related to the understanding of language. It plays a part in memory and emotions. It is also involved in hearing and visual sensations.[10]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3420617/
- Occipital lobe: This lobe contains the visual cortex and is concerned with visual inputs.[11]https://www.sciencedirect.com/topics/medicine-and-dentistry/occipital-lobe
Thalamus
Thalamus is a part of the diencephalon. Thalamus has several intra-thalamic nuclei.
With the assistance of nuclei, the thalamus performs the relaying of motor and sensory signals and the regulation of alertness and consciousness.[12]https://www.ncbi.nlm.nih.gov/books/NBK549908/
Hypothalamus
It is the master control center of the brain. It is involved in homeostasis and regulates blood pressure, water balance, and temperature.
It achieves this task by influencing endocrine outflow by controlling the pituitary gland and autonomic and somatic behavior.[13]https://www.ncbi.nlm.nih.gov/books/NBK525993/
Midbrain
Midbrain is also called the mesencephalon as it develops from it in prenatal life.[14]https://pubmed.ncbi.nlm.nih.gov/30252280/
Midbrain is located between the forebrain and the hindbrain. It is also part of the brain stem.
Parts of Midbrain
Midbrain has two major parts which are named tectum and tegmentum.
Tectum
It forms the back of the midbrain and has two swellings called superior and inferior colliculi.
The superior colliculus gets afferents from the retina and visual cortex and is involved in visual reflexes.
The inferior colliculus receives both crossed and uncrossed auditory fibers and relays information to the thalamus.[15]https://www.britannica.com/science/inferior-colliculus
Tegmentum
This region of the midbrain is present in front of the tectum. It is further composed of nerve tracts and three distinct regions.
These regions include the red nucleus. Substantia nigra, preaqueductal grey.
These regions are concerned with coordinating sensorimotor information, movement, motor coordination, and pain suppression, respectively.
General Functions of Midbrain
The midbrain plays an essential role in sensory and motor control pathways. It contains structures that are involved in movements regulation. It serves as a passage for the impulses between the spinal cord and higher centers in the brain. It is also concerned with consciousness and sleep.[16]https://pubmed.ncbi.nlm.nih.gov/31855353/
Hindbrain
The hindbrain is also called the rhombencephalon as it develops from in prenatal life.
The hindbrain further consists of the pons, medulla oblongata, and cerebellum.
The pons and cerebellum develop from the metencephalon, whereas the medulla oblongata develops from the myelencephalon.
Both the metencephalon and the myelencephalon are subdivisions of the rhombencephalon.[17]https://nba.uth.tmc.edu/neuroscience/m/s2/chapter01.html
Parts of Hindbrain
As already discussed hindbrain has three parts, the pons, medulla oblongata, and the cerebellum
Cerebellum
It is also called the “little brain” and is present under the cerebrum at the back of the skull.
The cerebellum is an ancient part of the brain with the cerebral cortex developed of it as humans evolved, so it performs primitive functions in the human body besides its advanced functions.[18]https://www.ncbi.nlm.nih.gov/mesh?Db=mesh&Cmd=DetailsSearch&Term=%22Cerebrum%22%5BMeSH+Terms%5D
Like the cerebrum, it also contains cortex and deep nuclei.[19]https://grants.hhp.uh.edu/clayne/6397/unit5_files/cerebell.htm
Lobes of Cerebellum
The cerebellum is thought to possess three lobes, the anterior lobe, the posterior lobe, and the flocculonodular lobes.[20]https://www.sciencedirect.com/topics/neuroscience/cerebellum
These lobes are separated from each other by two fissures. These fissures are named primary fissure and posterolateral fissure.
Functional areas of the Cerebellum
Cerebellum has three functional areas. Cerebrocerebellum is the largest area and is involved in planning movement and motor learning.
It is also involved in the coordination of muscle movements. The spinocerebellum is the one that allows error corrections and thus regulates body movements.
The area that is involved in balance is the vestibulocerebellum.[21]https://neuroscientificallychallenged.com/glossary/vestibulocerebellum/
Functions of Cerebellum
The cerebellum’s primary purpose is to regulate and monitor motor functions.
Initially, it was believed that the cerebellum’s central role is in coordinating movements.
Now, however, it is believed that it performs various functions that include balance, posture, motor learning, reflex memory, emotional processing, and sequence learning.
The cerebellum can also predict the fate of a particular ongoing movement and can adjust it if needed.[22]https://nba.uth.tmc.edu/neuroscience/m/s3/chapter05.html
Pons
It is a part of the hindbrain and is located in front of the cerebellum. In the brain stem, it is between the midbrain and the medulla.[23]https://www.sciencedirect.com/topics/neuroscience/medulla-oblongata The transverse section of pons divides it into two areas, the dorsal and ventral.
Ventral Pons
Pontine nuclei are present in the ventral portion. This area also has corticopontine and corticospinal tracts. It is bulky in appearance due to pontine nuclei.
Dorsal Pons
The reticular formation primarily occupies the dorsal pons.
It is bounded superiorly and laterally by the superior cerebellar peduncle and the inferior cerebellar peduncle.[24]https://www.ncbi.nlm.nih.gov/books/NBK560589/
Functions of Pons
Pons provides a variety of body functions. It is involved in communication for the center of the brain, focusing vision, balance, blinking, breathing regulation, sleep/awake cycles and facial expression.[25]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270924/
Pons gives rise to 10 cranial nerves that go to the face, neck, and trunk.
Medulla Oblongata
The medulla oblongata is a part of the hindbrain. It is present in the posterior cranial fossa and is the terminal part of the brain stem. It is inferior to pons and anterior to the cerebellum.[26]https://www.ncbi.nlm.nih.gov/mesh?Db=mesh&Cmd=DetailsSearch&Term=%22Medulla+Oblongata%22%5BMeSH+Terms%5D
Functional Areas of the Medulla
Medulla has many nuclei that have information coming from the spinal cord as well as higher centers of the brain.
These functional areas of the medulla include:
- the nucleus of the solitary tract,
- the area postrema,
- spinal trigeminal nucleus,
- inferior olivary nuclei,
- reticular formation,
- the cuneate nucleus, and gracilias nucleus,
- medial lemniscus,
- spinothalamic tract, and
- pyramidal decussations of the motor pathway26.
Cranial nerves and medulla oblongata
Hypoglossal (XII), accessory (XI), vagus (X), and glossopharyngeal (IX) are the cranial nerves that exit the medulla.
The abducens (VI), facial (VII), and vestibulocochlear are the cranial nerves that exit at the pons-medulla junction. XII, X, IX, and part of VIII cranial nerves have their nuclei situated in the medulla.[27]https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/medulla-oblongata
Functions of Medulla
The medulla oblongata controls autonomic functions.
It regulates the basic functions of the autonomic system that include heart rhythm, blood flow, and breathing.
This part of the brain also detects changes in blood oxygen and carbon dioxide levels. Medulla also originates reflexive responses such as coughing, vomiting, and swallowing.[28]https://www.hopkinsmedicine.org/health/conditions-and-diseases/anatomy-of-the-brain[29]https://www.medicalnewstoday.com/articles/brain
How To Keep The Brain Functioning and Healthy?
Brain health is as important as physical health. A healthy brain could prevent memory loss and prevent several other chronic conditions.
A person can follow these guidelines to keep his brain healthy and functioning.
- Keep blood sugar levels low
- Maintain proper weight
- Get enough sleep
- Avoid high blood pressure
- Keep an active social life
- Minimize alcohol consumption
- Not smoke
- Nootropics
Summary
The brain is the most complex structure in the human body. It has three main functional parts named forebrain, midbrain, and hindbrain.
These parts perform their above-mentioned individual functions and bring about the human body’s daily activities that ensure its survival.
Thus a healthy brain must be maintained to live a carefree life.
Taylor Bates
References
