What is the brain?

The brain is a complicated body organ that controls assumed, memory, eactivity, touch, motor abilities, vision, breathing, temperature, hunger and also eincredibly process that regulates our body. Together, the brain and spinal cord that exhas a tendency from it make up the central nervous mechanism, or CNS.

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What is the brain made of?

Weighing about 3 pounds in the average adult, the brain is about 60% fat. The remaining 40% is a mix of water, protein, carbohydrates and salts. The brain itself is a not a muscle. It has blood vessels and nerves, consisting of neurons and also glial cells.

What is the gray matter and also white matter?

Gray and white matter are 2 various areas of the central nervous device. In the brain, gray matter refers to the darker, outer percentage, while white issue describes the lighter, inner area underneath. In the spinal cord, this order is reversed: The white matter is on the outside, and also the gray matter sits within.


Gray issue is primarily composed of neuron somas (the round main cell bodies), and also white matter is mostly made of axons (the long stems that connects neurons together) wrapped in myelin (a protective coating). The various complace of neuron components is why the 2 show up as separate shades on certain scans.


Each region serves a different duty. Gray matter is mostly responsible for processing and also interpreting indevelopment, while white matter transmits that indevelopment to other parts of the nervous system.

How does the brain work?

The brain sends and receives chemical and also electrical signals throughout the body. Different signals regulate different procedures, and your brain interprets each. Some make you feel tired, for instance, while others make you feel pain.

Some messperiods are retained within the brain, while others are relayed via the spine and throughout the body’s vast netoccupational of nerves to far-off extremities. To perform this, the central nervous mechanism counts on billions of neurons (nerve cells).

Main Parts of the Brain and Their Functions

At a high level, the brain deserve to be separated into the cerebrum, brainstem and also cerebellum.



The cerebrum (front of brain) comprises gray issue (the cerebral cortex) and white matter at its center. The biggest component of the brain, the cerebrum initiates and also works with activity and also regulates temperature. Other areas of the cerebrum enable speech, judgment, reasoning and thinking, problem-fixing, eactivities and discovering. Other attributes relate to vision, hearing, touch and also various other senses.

Cerebral Cortex

Cortex is Latin for “bark,” and also explains the outer gray issue extending of the cerebrum. The cortex has a huge surchallenge area because of its folds, and also comprises around half of the brain’s weight.

The cerebral cortex is divided into 2 halves, or hemispheres. It is extended with ridges (gyri) and folds (sulci). The two halves sign up with at a large, deep sulcus (the interhemispheric fiscertain, AKA the medial longitudinal fissure) that runs from the front of the head to the earlier. The appropriate hemispbelow controls the left side of the body, and also the left fifty percent controls the best side of the body. The two halves connect through one an additional through a huge, C-shaped structure of white matter and also nerve pathmeans referred to as the corpus calloamount. The corpus calloamount is in the facility of the cerebrum.


The brainstem (middle of brain) connects the cerebrum through the spinal cord. The brainstem consists of the midbrain, the pons and the medulla.

Midbrain. The midbrain (or mesencephalon) is a very facility structure through a range of various neuron clusters (nuclei and also colliculi), neural pathmeans and other frameworks. These functions facilitate assorted features, from hearing and motion to calculating responses and ecological changes. The midbrain additionally includes the substantia nigra, a room influenced by Parkinson’s condition that is affluent in dopamine neurons and component of the basal ganglia, which enables activity and coordicountry. Pons. The pons is the origin for four of the 12 cranial nerves, which enable a selection of tasks such as tear manufacturing, chewing, blinking, concentrating vision, balance, hearing and facial expression. Named for the Latin word for “bridge,” the pons is the connection between the midbrain and the medulla. Medulla. At the bottom of the brainstem, the medulla is wbelow the brain meets the spinal cord. The medulla is essential to survival. Functions of the medulla control many bodily tasks, consisting of heart rhythm, breathing, blood circulation, and also oxygen and carbon dioxide levels. The medulla produces reflexive tasks such as sneezing, vomiting, coughing and swpermitting.

The spinal cord exoften tends from the bottom of the medulla and through a huge opening in the bottom of the skull. Supported by the vertebrae, the spinal cord carries messeras to and from the brain and also the rest of the body.


The cerebellum (“bit brain”) is a fist-sized portion of the brain located at the ago of the head, below the temporal and occipital lobes and over the brainstem. Like the cerebral cortex, it has actually 2 hemispheres. The external portion consists of neurons, and the inner location communicates via the cerebral cortex. Its function is to coordinate voluntary muscle activities and also to maintain posture, balance and also equilibrium. New research studies are experimenting the cerebellum’s duties in assumed, emotions and social behavior, as well as its possible involvement in addiction, autism and also schizophrenia.

Brain Coverings: Meninges

Three layers of protective extending referred to as meninges surround the brain and also the spinal cord.

The outera lot of layer, the dura mater, is thick and also challenging. It consists of two layers: The periosteal layer of the dura mater lines the inner dome of the skull (cranium) and the meningeal layer is listed below that. Spaces between the layers permit for the passage of veins and also arteries that supply blood circulation to the brain. The arachnoid mater is a thin, webfavor layer of connective tconcern that does not contain nerves or blood vessels. Below the arachnoid mater is the cerebrospinal fluid, or CSF. This liquid cushions the entire central nervous mechanism (brain and also spinal cord) and also continually circulates about these structures to rerelocate impurities. The pia mater is a thin membrane that hugs the surchallenge of the brain and complies with its contours. The pia mater is well-off with veins and also arteries.


Lobes of the Brain and What They Control

Each brain hemispright here (components of the cerebrum) has actually four sections, dubbed lobes: frontal, parietal, tempdental and occipital. Each lobe controls particular features.


Frontal lobe. The largest lobe of the brain, situated in the front of the head, the frontal lobe is connected in personality features, decision-making and also motion. Recognition of smell commonly requires parts of the frontal lobe. The frontal lobe has Broca’s location, which is linked via speech ability. Parietal lobe. The middle part of the brain, the parietal lobe helps a person recognize objects and understand also spatial relationships (where one’s body is compared with objects roughly the person). The parietal lobe is also affiliated in interpreting pain and touch in the body. The parietal lobe houses Wernicke’s area, which helps the brain understand also spoken language. Occipital lobe. The occipital lobe is the back part of the brain that is affiliated through vision. Temporal lobe. The sides of the brain, tempdental lobes are connected in short-lived memory, speech, musical rhythm and also some level of smell acknowledgment.

Deeper Structures Within the Brain

Pituitary Gland

Sometimes dubbed the “understand gland also,” the pituitary gland is a pea-sized structure uncovered deep in the brain behind the bridge of the nose. The pituitary gland governs the attribute of various other glands in the body, regulating the circulation of hormones from the thyroid, adrenals, ovaries and testicles. It receives chemical signals from the hypothalamus through its stalk and blood supply.


The hypothalamus is situated over the pituitary gland also and also sends out it chemical messperiods that regulate its feature. It regulates body temperature, synchronizes sleep fads, controls hunger and thirst and likewise plays a duty in some elements of memory and emovement.


Small, almond-shaped frameworks, an amygdala is located under each half (hemisphere) of the brain. Included in the limbic device, the amygdalae control eactivity and also memory and are connected via the brain’s reward system, stress and anxiety, and the “fight or flight” response as soon as someone perceives a risk.


A curved seahorse-shaped body organ on the underside of each tempdental lobe, the hippocampus is part of a bigger framework dubbed the hippocampal development. It supports memory, finding out, navigating and also perception of area. It receives indevelopment from the cerebral cortex and also may play a function in Alzheimer’s illness.

Pineal Gland

The pineal gland is situated deep in the brain and also attached by a stalk to the height of the 3rd ventricle. The pineal gland responds to light and also dark and also secretes melatonin, which regulates circadian rhythms and also the sleep-wake cycle.

Ventricles and Cerebrospinal Fluid

Deep in the brain are 4 open locations with passagemeans between them. They also open up into the main spinal canal and also the location beneath arachnoid layer of the meninges.

The ventricles manufacture cerebrospinal fluid, or CSF, a watery liquid that circulates in and also about the ventricles and the spinal cord, and between the meninges. CSF surrounds and also cushions the spinal cord and also brain, washes out waste and also impurities, and delivers nutrients.


Blood Supply to the Brain

Two sets of blood vessels supply blood and also oxygen to the brain: the vertebral arteries and the carotid arteries.

The outside carotid arteries extfinish up the sides of your neck, and also are wright here you have the right to feel your pulse when you touch the area with your fingertips. The internal carotid arteries branch right into the skull and also circulate blood to the front component of the brain.

The vertebral arteries follow the spinal column into the skull, wbelow they join together at the brainstem and also develop the basilar artery, which provides blood to the rear parts of the brain.

The circle of Willis, a loop of blood vessels near the bottom of the brain that connects major arteries, circulates blood from the front of the brain to the ago and helps the arterial systems interact via one an additional.


Cranial Nerves

Inside the cranium (the dome of the skull), there are 12 nerves, dubbed cranial nerves:

Cranial nerve 1: The first is the olfactory nerve, which permits for your feeling of smell. Cranial nerve 2: The optic nerve governs eyesight. Cranial nerve 3: The oculomotor nerve controls pupil response and also various other activities of the eye, and branches out from the location in the brainstem wbelow the midbrain meets the pons. Cranial nerve 4: The trochlear nerve controls muscles in the eye. It emerges from the earlier of the midbrain part of the brainstem. Cranial nerve 5: The trigeminal nerve is the largest and a lot of complicated of the cranial nerves, with both sensory and also motor feature. It originates from the pons and also conveys sensation from the scalp, teeth, jaw, sinprovides, components of the mouth and face to the brain, permits the function of chewing muscles, and also much even more. Cranial nerve 6: The abducens nerve innervates some of the muscles in the eye. Cranial nerve 7: The facial nerve supports challenge activity, taste, glandular and other features. Cranial nerve 8: The vestibulocochlear nerve facilitates balance and hearing. Cranial nerve 9: The glossopharyngeal nerve permits taste, ear and also throat motion, and also has many more functions. Cranial nerve 10: The vagus nerve enables sensation approximately the ear and also the digestive system and also controls motor task in the heart, throat and also digestive mechanism. Cranial nerve 11: The accessory nerve innervates particular muscles in the head, neck and also shoulder. Cranial nerve 12: The hypoglossal nerve supplies motor activity to the tongue.

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The first two nerves originate in the cerebrum, and the remaining 10 cranial nerves emerge from the brainstem, which has actually three parts: the midbrain, the pons and also the medulla.