Brain Anatomy | White Matter, Cerebellum, Cerebral Cortex, Medulla (2022)

The central nervous system (CNS) includes the brain and the spinal cord. The CNS is protected by bones and the meninges (the dura mater, arachnoid and pia mater). Cerebrospinal fluid cushions the CNS from damage. There are 86 main nerves branching off from the CNS – 12 pairs of cranial nerves that branch off from the brain and 31 pairs of spinal nerves that branch off from the spinal cord.

The brain, which is housed in and protected by the bones of the skull, makes up all parts of the central nervous system above the spinal cord. A human brain can weigh up to 3 pounds and is one of the largest organs of the body. Like the spinal cord, the brain is made of mainly gray matter and white matter arranged in distinct layers. The top of the brain appears as a soggy, pinkish-gray mass that looks like a walnut.

Parts of the Brain

The brain consists of the:

  • cerebrum
  • cerebellum
  • brain stem
  • diencephalon (thalamus and hypothalamus)
  • limbic system
  • reticular activating system

The brain can be divided into two major parts: the lower brain stem and the higher forebrain.

The brain stem sits above the spinal cord and has many connections between them. The brain stem, the most primitive part of the brain, is made up of the medulla, pons, cerebellum, midbrain, hypothalamus and thalamus. The cerebral cortex, limbic system and basal ganglia make up the forebrain. The forebrain deals with homeostasis, emotions and conscious actions.

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The brain’s outer layer is only 1/4 inch thick but if flattened out would cover the size of an office desk. It has about 50 billion nerve cells. The cerebrum is the largest part of the brain and is part of the forebrain. It houses the nerve center that controls sensory, motor activities and intelligence. The outer layer, the cerebral cortex, is made of nerve fibers called gray matter. The inner layer is made of a different type of nerve fibers called white matter.

The basal ganglia is found in the white matter. The cerebrum is divided in to left and right hemispheres. The left half controls the right side of the body and the right half controls the left side of the body. A mass of nerve fibers known as the corpus callosum connects the two hemispheres and allows communication between the two. The surface of the cerebrum is made up of gyri and sulci.

A cortex is the outer layer of any organ. The cerebral cortex is the outer layer of the brain, called gray matter. It is where our conscious thoughts and actions take place. Many of the signals our brain receives from our senses are registered in the cerebral cortex. The visual cortex is in the lower back part of the brain and is where our brain registers what we see. The somatosensory cortex is a band that runs over the top of the brain is where our brain registers a touch on any part of our body.

The motor cortex is just in front of the somatosensory cortex and it sends out signals to muscles to make them move. The more nerve endings a part of the body has, the more of the sensory cortex it occupies. A big portion of the sensory cortex is taken up by our lips and face. Our hands take up almost as much as our face and our feet almost as much as our hands. This is because we move our hands and lips all the time and both are very sensitive.

The cerebellum, “little brain”, is the second largest region of the brain. It is located behind and below the cerebrum and at the back of the brain stem and attached to the midbrain. It has two hemispheres and an outer cortex of gray matter and an inner core of white matter. The cerebellum is involved in movement and coordination, walking, posture, reflexes, eye and head movement. It coordinates subconscious movements such as balance and coordinated movement. The cerebellum is constantly receiving updates about the body’s position and movement. It also sends instructions to our muscles that adjust our posture and keep our body moving smoothly.

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The diencephalon is located between the cerebrum and midbrain. It consists of the thalamus and hypothalamus which lie deep in the cerebral hemispheres. Centers in the hypothalamus regulate our body temperature, blood sugar, hunger and hormones. The thalamus is involved with sensory signals sent to the higher forebrain, in particular the cerebral cortex. The thalamus also participates in motor control and regulating cortex excitement. Several pathways connect the brainstem to the lower motor centers in the spinal cord and the higher ones in the forebrain.

The brain is the control center of the body and contains billions of nerve cells. Thebrain stem lies just below the cerebrum and in front of the cerebellum. It continues from the cerebrum above and connects to the spinal cord below. The brain stem is made up of the midbrain, pons and medulla oblongata. It carries out many vital functions of the body for maintenance and survival such as breathing, heartbeat, and blood pressure. It also controls vomiting, coughing, sneezing and swallowing. It is the body’s “autopilot.” It also provides pathways for nerve fibers between the higher and lower neural centers. It is also the origin for 10 of the 12 cranial nerves. The 12 cranial nerves enter the brain directly and are not connected to the spinal cord.

The midbrain is the reflex center for cranial nerves III and IV and is involved in eye reflexes and movements. The pons helps regular breathing. It connects the cerebellum with the cerebrum and links the midbrain to the medulla oblongata. The pons is the reflex center for cranial nerves V through VIII. The pons is involved in chewing, taste, saliva, hearing and equilibrium. The medulla oblongata joins the spinal cord at the foramen magnum. It influences heart, breathing and circulation. It’s the center for vomiting, coughing and hiccuping.

Themedulla—the most primitive brain structure—controls our digestive, respiratory and circulatory systems. Theponsinteracts with the cerebellum, motor control and respiration. Other structures in the pons control sleep and excitement. The pons also relays information between the brain and the spinal cord.

Thebasal ganglia is found in the forebrain and consist of structures involved in motor processes. The basal ganglia works along with the motor areas of the cortex and cerebellum for planning and coordinating certain voluntary movements. The basal ganglia is made of gray matter.

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Thelimbic system, or limbic lobe, is involved in the expression of intimate behaviors and emotions, hunger, aggression. The limbic system also screens all sensory messages to the cerebral cortex. It is located deep in the temporal lobe. The limbic system includes these structures: cingulate gyrus, corpus callosum, mammillary body, olfactory tract, amygdala, and hippocampus. The hypothalamus affects body temperature, appetite, water balance, pituitary secretions, emotions, and autonomic functions including cycles of waking and sleeping.

Even though many functions of the brain are very localized to certain areas and parts of the brain, these parts work together as a whole—particularly in learning, memory, and consciousness.

Ventricles are fluid filled cavities in the brain; there are four of them. The ventricles connect with each other and produce cerebrospinal fluid which is a clear, shock-absorbing liquid that is constantly moving. The cerebrospinal fluid cushions the brain, distributes nutrients and collects wastes.

Blood Vessels in the Brain

The oxygen supply for the brain comes from 4 major arteries, two vertebral arteries and two carotid arteries. The two vertebral arteries supply blood to the back of the brain. The two carotid arteries branch and supply oxygen to the front and middle of the brain. The front and back arteries interconnect at the circle of Willis at the base of the brain. The circle of Willis ensures a continuous blood supply to the brain.

Cross Section Images of the Brain

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Brain Anatomy | White Matter, Cerebellum, Cerebral Cortex, Medulla (2)

Sectioning the Brain

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Left and Right Hemispheres

The forebrain consists of two almost symmetrical cerebral hemispheres made up of the cerebral cortex, the basal ganglia and the limbic system. The two hemispheres are divided by the longitudinal cerebral fissure and connected by a massive bundle of fibers called the corpus callosum. The surface of the two hemispheres is covered by a large, but thin layer of nerve cells called gray matter. Because of the area size of the gray matter, fitting it into the skull causes folds. The grooves in these folds are called sulci (singular sulcus), the ridges are called gyri (singular gyrus). The deeper grooves are called fissures. The cortex is a large mass of nerve fibers called white matter. These nerve fibers are highly developed and able to analyze both motor and sensory information.

The left and right hemispheres may look the same, but each side functions differently. Speech and language, reasoning and analysis, and certain communications are on the left side for most people. The left side of the brain sends and receives information to the right side of the body including the right hand. The right hemisphere is concerned with sensory input, auditory and visual awareness, creative abilities, and spatial-temporal awareness—that is what is happening around us moment by moment. The right brain controls the left side of the body.

Each of the cerebral hemispheres is divided into four lobes and are name for the cranial (skull) bones that lie over them:

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  • The frontal lobe extends from the tip of the front of the hemisphere to the central sulcus. The back areas of the frontal lobe specialize in motor functions, including language and voluntary movement; the front areas are involved in learning, planning and other higher psychological processes like our personality and behavior.
  • The occipital lobe is at the back of the hemisphere and is involved in interpreting visual stimuli, that is, what we see.
  • The parietal lobes are at the top and outside areas between the occipital lobe and the frontal lobe and is involved in sensory functions of the skin including pain, temperature, and touch. It also interprets size, shape, distance, vibrations and texture. Other areas are also important in cognitive and intellectual processes.
  • The temporal lobe controls the hearing centers, language comprehension, storing and recalling memories and related areas including some speech centers. Other areas of the brain also affect memory. The front and bottom areas of the temporal lobe are involved in smell and functions of the limbic system.

Brain Injury: A guide for family and friends

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Common Problems During Early Recovery
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How You Can Help With Recovery
Where Will the Journey Go From Here?
How Will I Ever Get Through This?
Where to Go for Help
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FAQs

What are the 4 parts of the brain and what do they do? ›

The frontal lobes are responsible for problem solving and judgment and motor function. The parietal lobes manage sensation, handwriting, and body position. The temporal lobes are involved with memory and hearing. The occipital lobes contain the brain's visual processing system.

What is cerebrum cerebellum and medulla? ›

Cerebellum: Cerebellum lies below the cerebrum and at the back of the whole structure. It coordinates the motor functions. When you are riding your bicycle; the perfect coordination between your pedaling and steering control is achieved by the cerebellum. Medulla: Medulla forms the brain stem; along with the pons.

What are 5 functions of the brain? ›

Your brain enables:
  • Thoughts and decisions.
  • Memories and emotions.
  • Movements (motor function), balance and coordination.
  • Perception of various sensations including pain.
  • Automatic behavior such as breathing, heart rate, sleep and temperature control.
  • Regulation of organ function.
  • Speech and language functions.
30 Mar 2022

What are the 3 types of the brain? ›

The brain can be divided into three basic units: the forebrain, the midbrain, and the hindbrain. The hindbrain includes the upper part of the spinal cord, the brain stem, and a wrinkled ball of tissue called the cerebellum. The hindbrain controls the body's vital functions such as respiration and heart rate.

What are the 3 parts of brain and their functions? ›

The brain has three main parts:
  • The cerebrum fills up most of your skull. It is involved in remembering, problem solving, thinking, and feeling. ...
  • The cerebellum sits at the back of your head, under the cerebrum. It controls coordination and balance.
  • The brain stem sits beneath your cerebrum in front of your cerebellum.

Which parts of brain controls what? ›

Not all functions of the hemispheres are shared. In general, the left hemisphere controls speech, comprehension, arithmetic, and writing. The right hemisphere controls creativity, spatial ability, artistic, and musical skills. The left hemisphere is dominant in hand use and language in about 92% of people.

What is brain made up of? ›

The human brain is primarily composed of neurons, glial cells, neural stem cells, and blood vessels. Types of neuron include interneurons, pyramidal cells including Betz cells, motor neurons (upper and lower motor neurons), and cerebellar Purkinje cells.

What is medulla? ›

Your medulla is the bottom-most part of your brain, connecting to your spinal cord through the foramen magnum, an opening at the bottom of your skull. Just above your medulla is your pons, which is just below the central structures in your brain.

What is cerebellum function? ›

Your cerebellum is part of your brain that helps coordinate and regulate a wide range of functions and processes in both your brain and body. While it's very small compared to your brain overall, it holds more than half of the neurons (cells that make up your nervous system) in your whole body.

What are functions of cerebrum? ›

The cerebrum is the upper part of the brain, handling many different functions, including muscle movements, language, processing what your senses pick up and more.

Is the brain an organ? ›

As it turns out, your brain isn't actually a muscle. It's an organ — one that actually plays a huge role in controlling muscles throughout your body.

Is the brain a muscle? ›

Is the brain a muscle or organ? The brain is an organ, and a very unusual and complex one at that. It plays a role in every one of our functions, controlling many organs, our thoughts, memory, speech, and movements.

Where is brain located? ›

The brain is housed inside the bony covering called the cranium. The cranium protects the brain from injury. Together, the cranium and bones that protect the face are called the skull. Between the skull and brain is the meninges, which consist of three layers of tissue that cover and protect the brain and spinal cord.

Which acid is present in brain? ›

Sialic Acids in the Brain: Gangliosides and Polysialic Acid in Nervous System Development, Stability, Disease, and Regeneration.

What is the small brain called? ›

For the longest time the cerebellum, a dense, fist-size formation located at the base of the brain, never got much respect from neuroscientists.

What is the largest part of the brain? ›

Anatomy of the brain. The cerebrum is the largest part of the brain, accounting for 85 percent of the organ's weight. The distinctive, deeply wrinkled outer surface is the cerebral cortex. It's the cerebrum that makes the human brain—and therefore humans—so formidable.

Which part of the brain is most critical? ›

Medulla. The lowest part of the brainstem, the medulla is the most vital part of the entire brain and contains important control centers for the heart and lungs.

What part of brain controls sleep? ›

The hypothalamus, a peanut-sized structure deep inside the brain, contains groups of nerve cells that act as control centers affecting sleep and arousal.

What color is the brain? ›

The brain is a pinkish, grayish color, and that's thanks to the parts that compose it. Most of the brain is made of cells called grey matter that are, in fact, gray.

Which side of the brain is used for memory? ›

Our brains have two sides, or hemispheres. In most people, language skills are in the left side of the brain. The right side controls attention, memory, reasoning, and problem solving.

How is memory stored in the brain? ›

All memory storage devices, from your brain to the RAM in your computer, store information by changing their physical qualities. Over 130 years ago, pioneering neuroscientist Santiago Ramón y Cajal first suggested that the brain stores information by rearranging the connections, or synapses, between neurons.

Who named the brain? ›

From etymological dictionaries, such as the great 32-volume work assembled in the 19th century by the “brothers Grimm” we find that the modern word “brain” is derived from the Old English “braegen”, which is the word that still exists in other western Germanic languages, e.g. “brein” in Danish and Friesian.

What is the size of human brain? ›

The human brain continues to grow until it reaches its peak size in the third to fourth decade of life. An MRI study of 46 adults of mainly European descent found that the average male had a brain volume of 1,274 cubic centimeters (cm3) and that the average female brain measured 1,131 cm3.

How is brain formed? ›

The human brain develops from the tip of a 3-millimeter-long neural tube. At three to four weeks after conception, the neural groove closes into a tube, and three distinct regions—a hindbrain, midbrain, and forebrain—begin to take form.

What is a midbrain? ›

The midbrain is the topmost part of the brainstem, the connection central between the brain and the spinal cord. There are three main parts of the midbrain - the colliculi, the tegmentum, and the cerebral peduncles.

What is brain stem? ›

The brain stem is the lower part of the brain that's connected to the spinal cord (part of the central nervous system in the spinal column). The brain stem is responsible for regulating most of the body's automatic functions that are essential for life. These include: breathing. heartbeat.

What are the 3 main centers in the medulla? ›

The medulla contains the cardiac, respiratory, vomiting and vasomotor centers, and therefore deals with the autonomic functions of breathing, heart rate and blood pressure as well as the sleep–wake cycle.

What are the 3 parts of the cerebellum? ›

There are three functional areas of the cerebellum – the cerebrocerebellum, the spinocerebellum and the vestibulocerebellum. Cerebrocerebellum – the largest division, formed by the lateral hemispheres. It is involved in planning movements and motor learning.

What is the size of the cerebellum? ›

In humans, the cerebellar cortex is a single continuous sheet with an area of 500 cm2 (1,000 mm long and 50 mm wide) .

How is the cerebellum damaged? ›

Cerebellum brain damage often occurs due to anoxic brain injury, neurodegenerative disorders, or infection. Alcohol abuse can also cause the cerebellum to deteriorate. When the cerebellum sustains damage, the signals it sends throughout the body become weaker or can cease entirely.

What are the 3 major regions of the cerebrum? ›

[1] There are three main divisions cerebrum, cerebellum, brain stem. The cerebrum consists of two cerebral hemispheres the outer layer called the cortex (gray matter) and the inner layer (white matter).

Does the cerebrum control memory? ›

It has a wrinkled appearance from its many folds and grooves. Your cerebral cortex plays a key role in memory, thinking, learning, reasoning, problem-solving, emotions, consciousness and functions related to your senses. Anatomy of the cerebral cortex.

What are the 3 main parts of the brain and their functions? ›

The brain has three main parts:
  • The cerebrum fills up most of your skull. It is involved in remembering, problem solving, thinking, and feeling. ...
  • The cerebellum sits at the back of your head, under the cerebrum. It controls coordination and balance.
  • The brain stem sits beneath your cerebrum in front of your cerebellum.

Which part of the brain is most important and why? ›

The cerebrum (forebrain) is the most important part of the human brain.

What part of the brain controls memory and emotion? ›

Amygdala: Limbic structure involved in many brain functions, including emotion, learning and memory.

How do you remember parts of your brain? ›

How to learn major parts of the brain quickly - YouTube

What is brain made up of? ›

The human brain is primarily composed of neurons, glial cells, neural stem cells, and blood vessels. Types of neuron include interneurons, pyramidal cells including Betz cells, motor neurons (upper and lower motor neurons), and cerebellar Purkinje cells.

What system is the brain in? ›

The Nervous System

The central nervous system is made up of the brain, its cranial nerves and the spinal cord. The peripheral nervous system is composed of the spinal nerves that branch from the spinal cord and the autonomous nervous system (divided into the sympathetic and parasympathetic nervous system).

How do brains work? ›

Your brain contains billions of nerve cells arranged in patterns that coordinate thought, emotion, behavior, movement and sensation. A complicated highway system of nerves connects your brain to the rest of your body, so communication can occur in split seconds.

Which part of the brain is most critical? ›

Medulla. The lowest part of the brainstem, the medulla is the most vital part of the entire brain and contains important control centers for the heart and lungs.

What is the most sensitive part of the head? ›

Forehead and fingertips most sensitive to pain, research shows | Neuroscience | The Guardian.

What part of the brain controls vision? ›

Which Part of the Brain Controls Vision? Visual functions are mostly controlled in the occipital lobe of the brain. The occipital lobe is a small area in the brain in the back of the skull.

Which brain part controls stress? ›

The amygdala is the brain structure that actually detects stress and tells the HPA axis to respond. It can detect both emotional and biological stressors.

What part of the brain controls anxiety? ›

The brain's limbic system, comprised of the hippocampus, amygdala, hypothalamus and thalamus, is responsible for the majority of emotional processing. Individuals with an anxiety disorder may have heightened activity in these areas. “Anxiety can be severely debilitating and good treatments are available,” says Dr.

What part of the brain controls anger? ›

When an angry feeling coincides with aggressive or hostile behavior, it also activates the amygdala, an almond–shaped part of the brain associated with emotions, particularly fear, anxiety, and anger.

Which brain controls right hand? ›

The cerebrum can be anatomically divided into two parts: the right and left hemispheres. The right hemisphere controls the left side of the body, and the left hemisphere controls the right side.

Where is memory stored in the brain? ›

For explicit memories – which are about events that happened to you (episodic), as well as general facts and information (semantic) – there are three important areas of the brain: the hippocampus, the neocortex and the amygdala. Implicit memories, such as motor memories, rely on the basal ganglia and cerebellum.

What makes up 85 of the brain? ›

The cerebrum makes up 85% of the brain's weight, and the brain makes up about 2% of a human's body weight.

Videos

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4. Gray and white matter | Organ Systems | MCAT | Khan Academy
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