The Many Parts of the Human Brain and How They Function
Table of Contents:
- What is the human brain?
- The three parts of the brain
- Right brain vs. left brain
- The lobes of the brain
- The cerebrum
- Cranial nerves
- The brain is a complex symphony
The human brain is the control center of the entire body - it’s responsible for movement, thought, memory, feelings, hunger, and every other thing we experience in our lives. There are many moving parts within the brain working together to ensure the body functions and survives. Much like a symphony, every aspect of our brain carefully collaborates to create one unified result.
A symphony usually has 80 to 100 people working together, each playing their own instrument to contribute their part to the elaborate musical composition. In the same way, each part of the brain must play its role so that we function properly. When one player is off-key, there’s a noticeable change in the song. Similarly, when one aspect of the brain is out of order, the rest of the brain is affected. For the highest function, we need each part to work in unison. Thanks to neuroscience, we have a wealth of knowledge on each part of the brain.
What is the human brain?
The brain is about three pounds of soft tissue. The gray and white matter that make up our brain’s mass contain nerve cells and non-neuronal cells. The latter are what make up the software that our bodies run on. The human brain itself is about 60% fat, with the rest being water, carbohydrates, protein, and salts.
Together, all of these parts control our thoughts, motor skills, body temperature, emotions, memory, and senses. The brain connects to the spinal cord, and together they make up the central nervous system (CNS.) (1) Without the brain and its network of the CNS, people cannot survive - these components are crucial to life. Properly feeding and protecting the brain is the key to our quality of life.
The three parts of the brain
While there are many structures in the brain, it can be broken down into three main parts: the cerebrum, cerebellum, and brainstem.
The cerebrum is responsible for regulating temperature and movement - without it, we couldn’t coordinate or initiate action. It also helps with:
The senses (hearing, vision, taste, touch, smell)
Reasoning and thinking
Problem-solving and learning
In the brain, gray matter is the exterior of the brain, while white matter is found at the center. The cerebrum houses both and is the front section of the brain. The cerebral cortex, which covers the cerebrum, is made of gray matter and is responsible for 50% of the brain’s overall weight.
The cerebellum is about the size of a fist and sits at the back of the head, above the brainstem. It’s broken into two hemispheres - the outer, which contains neurons, and the inner, which communicates with the cerebral cortex. The cerebellum is responsible for:
Coordination of voluntary muscle movement
The cerebellum may also play a role in emotions, thinking, and social behavior. While still undetermined, neuroscience studies are being performed to determine its level of involvement in these functions. (1)
The brainstem connects the spinal cord and cerebrum and is found in the middle of the brain. It’s made up of the midbrain, medulla, and pons. The midbrain is very complex, with neural pathways and neuron clusters that help calculate responses and understand environmental changes, hearing, and movement.
The medulla connects the brain and spinal cord at the lower end of the brainstem. It’s responsible for essential bodily functions like breathing, heart rhythm, and blood flow. Whenever you swallow, cough, sneeze, or vomit, you can thank your medulla.
The pons bridges the midbrain and medulla and is named after the Latin word for bridge. Of the 12 cranial nerves, it contains four and helps us chew, blink, produce tears, focus our vision, make facial expressions, and hear. (1)
Right brain vs. left brain
You’ve likely heard of people’s personalities skewing more right-brained or left-brained, with the former being creative types and the latter being analytical types. (2) In reality, these two hemispheres of the cerebrum must work together for proper function, though they each have their own individual purposes. The left hemisphere controls the right side of the body - the right controls the left side of the body.
The right hemisphere of the brain controls art and music skills, creativity, and spatial ability. The left hemisphere of the brain controls comprehension, writing, arithmetic, and speech. For 92% of people, the left hemisphere is also dominant for language and hand use. The two hemispheres are connected by the corpus callosum, which is a bundle of fibers that sends messages between the hemispheres. (3)
The lobes of the brain
Within each of the cerebral hemispheres, defined fissures separate the hemisphere into four lobes: the frontal lobe, parietal lobe, occipital lobe, and temporal lobe. These lobes, while responsible for specific functions, cannot work on their own. They must collaborate through complex relationships with other lobes and the hemispheres of the brain.
Broca’s area: speech and writing
Motor strip: body movement
Personality, emotions, and behavior
Planning, problem-solving, and judgment
Concentration, intelligence, and self-awareness
Sensory strip: temperature, pain, sense of touch
Language and words
Vision signal interpretation, spatial perception, motor, hearing, sensory, and memory
Interprets color, light, and movement for overall vision
Wernicke’s area: understanding language
Organizing and sequencing
As the cerebrum is the largest of the three parts of the human brain, it also contains many structures. These structures are highlighted below:
The cortex, or surface of the cerebrum, contains 16 billion neurons, which are layered in a specific way. While the nerve cell bodies make the cortex a grayish-brown color, the long nerve fibers under the cortex are white and are also known as white matter. The folds (also referred to as gyrus) of the cortex create more surface area, which allows for more neurons and thus higher brain function.
Deep structures, as the name implies, are those found deeper in the brain. By using white matter tracts, which are pathways that connect the different areas of the cortex, the brain can send messages. Messages can go between lobes, from one fold to another and directly to deep structures.
The limbic system is the center of activity for emotions, memory, and learning. Within the limbic system, we find the hypothalamus, cingulate gyri, amygdala, and hippocampus. (3)
There’s an amygdala under each half of the brain. The almond-shaped structure is responsible for emotional reactions, the fight or flight response, and reward systems. (1)
Underneath each temporal lobe, we find a curved organ known as the hippocampus. It plays a part in memory, navigation, spatial perception, and learning. Information is sent to the hippocampus by the cerebral cortex. (1)
Found in the third ventricle, the hypothalamus controls the autonomic system. It helps to regulate blood pressure, body temperature, hormone secretion, and emotions. Thirst, hunger, sexual response, and sleep are all partially controlled by the hypothalamus. (3)
Connected to the hypothalamus by the pituitary stalk is the pituitary gland. It’s responsible for secreting hormones for sexual development, responds to stress, and promotes muscle and bone growth. It controls the body’s endocrine glands.
The pineal gland is found in the third ventricle and releases melatonin, which maintains the body’s circadian rhythm and internal clock.
The thalamus helps with attention, alertness, pain sensation, and memory. It acts as a relay station, distributing all the information that comes in and out of the cortex.
The caudate, globus pallidus, and putamen are nuclei that are included in the basal ganglia - together, they work with the cerebellum to create fine motor skills. When you move your fingertips and flex your toes, it’s the work of this collaboration. (3)
The ventricles are four open areas linked together by passageways. They open into the central spinal cord. Manufactured in the ventricles is cerebrospinal fluid (CSF.) This watery liquid circulates between the spinal cord, ventricles, and meninges. It acts as a cushion by surrounding the brain and spinal cord. It delivers nutrients while also washing out impurities and waste. (1)
While the central nervous system is made up of the spinal cord and brain, the peripheral nervous system (PNS) consists of the spinal and cranial nerves. By way of these cranial nerves and the spinal cord, the brain can communicate with the body.
There are twelve cranial nerves, ten of which originate in the brainstem. These nerves control facial sensations and movement, eye movement, hearing, taste, swallowing, and movement of the face, shoulders, neck, and tongue muscles. (3)
Olfactory: This nerve provides the sense of smell.
Optic: This nerve governs sight.
Oculomotor: This nerve controls eye motions, including pupil response. It emerges from the brainstem, where the pons and midbrain meet.
Trochlear: Emerging from the hindquarters of the midbrain on the brainstem, this nerve controls eye muscles.
Trigeminal: Originating from the pons, this nerve provides sensation in the scalp, jaw, teeth, sinuses, and some parts of the face and mouth. It helps the chewing muscles function and contributes to sensory and motor function. It’s the most complex and largest cranial nerve.
Abducens: This nerve is related to some eye muscles.
Facial: Facial movement, taste, and glandular functions are made possible by this nerve.
Vestibulocochlear: This nerve aids with hearing and balance.
Glossopharyngeal: Among its many functions, this nerve supports ear, taste, and throat movement.
Vagus: This nerve provides sensation around the digestive system and ear. It also controls motor activity in the digestive system, throat, and heart.
Accessory: This nerve innervates some muscles in the neck, head, and shoulders.
Hypoglossal: The tongue’s motor activity is provided by this nerve. (1)
The brain is a complex symphony
The brain is a complicated structure. In order to orchestrate movement, thought, memory, senses, breathing, feeling, hunger, and everything else humans experience each day, it takes a very complex organ. From the three main parts of the brain - the cerebrum, cerebellum, and brainstem - to the left and right hemispheres, the frontal lobe, and the various other lobes, all the way down to the cranial nerves - each piece of the brain plays a critical role in overall health and function.
If we want to experience perfect function, we must take care of our brain health. By being vigilant about caring for and feeding our brains, we protect the most important organ in our bodies - the human brain.
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