Thursday, June 16, 2022

Are There Nerves In The Brain

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So How Many Nerves All Together

The Brain and Cranial Nerves Part 1

There are several hundred peripheral nerves throughout your body. The many sensory nerves that bring sensation from the skin and internal organs merge together to form the sensory branches of the cranial and spinal nerves.

The motor portions of the cranial nerves and spinal nerves divide into smaller nerves that divide into even smaller nerves. So one spinal or cranial nerve may divide into anywhere from 2 to 30 peripheral nerves.

The Central Nervous System : The Neurons Inside The Brain

The Central Nervous System, or CNS for short, is made up of the brain and spinal cord . The CNS is the portion of the nervous system that is encased in bone . It is referred to as central because it is the brain and spinal cord that are primarily responsible for processing sensory informationtouching a hot stove or seeing a rainbow, for exampleand sending signals to the peripheral nervous system for action. It communicates largely by sending electrical signals through individual nerve cells that make up the fundamental building blocks of the nervous system, called neurons. There are approximately 86 billion neurons in the human brain and each has many contacts with other neurons, called synapses .

If we were to zoom in still further we could take a closer look at the synapse, the space between neurons . Here, we would see that there is a space between neurons, called the synaptic gap. To give you a sense of scale we can compare the synaptic gap to the thickness of a dime, the thinnest of all American coins . You could stack approximately 70,000 synaptic gaps in the thickness of a single coin!

It is amazing to realize that when you thinkwhen you reach out to grab a glass of water, when you realize that your best friend is happy, when you try to remember the name of the parts of a neuronwhat you are experiencing is actually electro-chemical impulses shooting between nerves!

Can The Brain Itself Feel Pain

Does the brain itself have pain receptors?

There are no pain receptors in the brain itself. But he meninges , periosteum , and the scalp all have pain receptors. Surgery can be done on the brain and technically the brain does not feel that pain.

With that said, the brain is the tool we use to detect pain. Lets say youre on the beach and you step on a sharp shell. Special pain receptors in your skin activate whenever there has been an injury, or even a potential injury, such as breaking the skin or causing a large indentation. Now, an impulse is heading through the nerve into the spinal cord, and eventually all the way to your brain. This happens within fractions of a second.

Signals are also sent from the thalamus to the limbic system, which is the emotional center of the brain. Feelings are associated with every sensation you encounter, and each feeling generates a response. For example, your heart rate may increase, and you may break out into a sweat.

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Signs And Symptoms Of Cranial Nerve Disorders

Cranial nerve issues can show up in people of any age. The symptoms you might experience depends on each cranial nerves function. Some of the most common signs that can indicate a cranial nerve disorder include:

  • Pain in different regions of the body
  • Tingling sensations in places like your arms, legs, or neck
  • Skin sensitivity when touched
  • Inability to control your facial expression
  • Problems with speech

What Are The Parts Of The Nervous System

The human brain and nervous system

The nervous system is made up of the central nervous system and the peripheral nervous system:

  • The brain and the spinal cord are the central nervous system.
  • The nerves that go through the whole body make up the peripheral nervous system.

The human brain is incredibly compact, weighing just 3 pounds. It has many folds and grooves, though. These give it the added surface area needed for storing the body’s important information.

The spinal cord is a long bundle of nerve tissue about 18 inches long and 1/2-inch thick. It extends from the lower part of the brain down through spine. Along the way, nerves branch out to the entire body.

Both the brain and the spinal cord are protected by bone: the brain by the bones of the skull, and the spinal cord by a set of ring-shaped bones called vertebrae. They’re both cushioned by layers of membranes called meninges and a special fluid called cerebrospinal fluid. This fluid helps protect the nerve tissue, keep it healthy, and remove waste products.

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According To The Direction In Which The Nerve Impulse Is Transmitted

Nerves can be classified in 3 ways, depending on the direction in which they transmit the nerve impulse.

Motor nerves

The motor nerves are responsible for all voluntary skeletal and somatic movement , they conduct the nerve impulse to the muscles and glands.

Sensitive nerves

The sensitive nerves are responsible for conducting the nervous impulse towards the central nervous system, that is, from the receptors to the coordination centers

Mixed nerves

Mixed nerves conduct nerve impulses in both directions and have both sensory and motor axons.

What Makes Up A Nerve Cell

Your neurons work to conduct nerve impulses. They have three parts:

  • Cell body: Similar to the other cells in your body, this area contains various cellular components like the nucleus.
  • Dendrites: Dendrites are extensions from the cell body. They receive signals from other neurons. The number of dendrites on a neuron can vary.
  • Axon: The axon also projects from the cell body. Its typically longer than the dendrites and carries signals away from the cell body where they can be received by other nerve cells. Axons are often covered by a substance called myelin, which helps to protect and insulate the axon.

Your brain alone contains approximately

So how exactly do neurons work? Lets explore one type of neuron signaling below:

  • When neurons signal another neuron, an electrical impulse is sent down the length of the axon.
  • At the end of the axon, the electrical signal is converted into a chemical signal. This leads to the release of molecules called neurotransmitters.
  • The neurotransmitters bridge the gap, called a synapse, between the axon and the dendrites of the next neuron.
  • When the neurotransmitters bind to the dendrites of the next neuron, the chemical signal is again converted into an electrical signal and travels the length of the neuron.
  • Nerves are made up of bundles of axons that work together to facilitate communication between the CNS and PNS. Its important to note that peripheral nerve actually refers to the PNS. Axon bundles are called tracts in the CNS.

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    Types Of Cranial Nerve Disorders

    Some examples of common disorders that are related to your cranial nerves include:

    Trigeminal neuralgia

    This condition results from a malfunctioning of the trigeminal cranial nerve. You experience severe facial pain, typically due to an artery’s abnormal positioning that puts pressure on the nerve. It can feel like short bursts of stabbing pain in the lower part of your face.

    Bell palsy

    You typically experience paralysis or weakness on one side of their face when the facial cranial nerve stops functioning correctly. Bell palsy, or Bells palsy, can be brought on by an immune disorder or a viral infection. You may lose the ability to taste things with the front of your tongue on the side of your face that is affected.

    Internuclear ophthalmoplegia

    Damage to the lower part of the brain stem can lead to issues with your horizontal eye movement, sometimes leading to double vision. This cranial nerve disorder usually occurs when there is an injury to the fibers connecting the oculomotor nerve, the trochlear nerve, and the abducens nerve. Internuclear ophthalmoplegia often occurs in people whove had a stroke or in younger people with multiple sclerosis.

    • Certain medications

    Neurones Are The Building Blocks

    Cranial Nerves: Neuroanatomy Video Lab – Brain Dissections

    The basic building block of the nervous system is a nerve cell, or neurone. Neurones are shaped differently depending on where they are in the body and what role they play. All neurones have finger-like projections called dendrites and a long fibre called an axon.In many cases, the axon is coated by a specialised membrane called a myelin sheath. The axon feathers out and has a number of bumps on it. Each bump sits near to a dendrite from another neurone. The space between the bump and the dendrite is called a synapse. Messages jump the synapse from one neurone to the next, using special chemicals called neurotransmitters.Unlike other cells in the body, neurones arent easily replaced if they die or are damaged by infection or injury.

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    Organization Of The Nervous System

    Your nervous system has two divisions:

    • Central nervous system : The CNS is the bodys command center and is made up of your brain and spinal cord. The brain is protected within your skull while your vertebrae protect your spinal cord.
    • Peripheral nervous system : The PNS is made up of nerves that branch off from your CNS. Nerves are bundles of axons that work together to transmit signals.

    The PNS can be further broken up into sensory and motor divisions:

    • Thesensory division transmits information from both inside and outside of your body to your CNS. This can include things like feelings of pain, smells, and sights.
    • Themotor division receives signals from the CNS that cause an action to occur. These actions can be voluntary, such as moving your arm, or involuntary like the muscle contractions that help move food through your digestive tract.

    The Immune Response In The Brain Is Different From That In Skin

    The immune response plays an essential role in any kind of repair after injury. In injured skin, immune cells will rush to the site of injury from the blood and help the resident immune cells clean up debris from dead cells. Once the clean up is done, the immune cells die and stop the fight. The brain has specialized resident immune cells as well, and they will become activated when they sense danger or damage. A common problem in the brain is that the activated immune cells often dont know when to stop fighting. If they continue to spit out toxic chemicals over long periods, they can cause more harm than good, by killing healthy neurons. This is why scientists are trying to understand what switches brain immune cells on and off and trying to figure out how they can modify the response of these immune cells, so the cells can be helpful rather than harmful .

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    What Are The 12 Cranial Nerves And Their Functions

    The 12 cranial nerves and their functions are as follows:

    Now that you know a little more about cranial nerves, what they do, and some of the functions they control, you can see how important they are for overall health and well-being. When one of these cranial nerves is damaged or not working properly, it can cause problems with movement, hearing, balance, taste, and other functions. If you experience any problems with any of your cranial nerves, be sure to speak to a doctor. They will be able to help diagnose the problem and provide the necessary treatment.

    What Do Cranial Nerves Do

    Olfactory Nerves In The Brain, Artwork Photograph by Roger Harris

    The cranial nerves play a major role in sensory perception, facial expression, eye movement, balance and coordination of the head and neck regions, as well as speech production. Some cranial nerve functions include olfaction, sense of taste, vision also called ophthalmic, sense of smell or nasal, hearing and balance or auditory, facial sensation and movement also called maxillary, mandibular, and cervical, and lastly speech and swallowing which can be called facial, and hypoglossal.

    Cranial nerve damage can result in a wide variety of symptoms depending on the nerve involved. For example, cranial nerve VII, or the facial nerve, controls the muscles of facial expression. Damage to this nerve can cause facial palsy which is a weakness or paralysis on one side of the face, resulting in a droopy eyelid, a crooked smile, and difficulty chewing and swallowing.

    Cranial nerves should not be confused with spinal nerves, which are also part of the peripheral nervous system. The spinal nerves exit the cranial cavity through openings between the cranial bones, but they do not go to your brain. They travel down from your skull and branch out to all areas of the body before connecting with spinal cord segments that then lead back up into the brain stem or down into the rest of your spine.

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    About The Brain And Spinal Cord

    Together, the brain and spinal cord form the central nervous system. This complex system is part of everything we do. It controls the things we choose to dolike walk and talkand the things our body does automaticallylike breathe and digest food. The central nervous system is also involved with our sensesseeing, hearing, touching, tasting, and smelling as well as our emotions, thoughts, and memory.

    The brain is a soft, spongy mass of nerve cells and supportive tissue. It has three major parts: the cerebrum, the cerebellum, and the brain stem. The parts work together, but each has special functions.

    The cerebrum, the largest part of the brain, fills most of the upper skull. It has two halves called the left and right cerebral hemispheres. The cerebrum uses information from our senses to tell us what’s going on around us and tells our body how to respond. The right hemisphere controls the muscles on the left side of the body, and the left hemisphere controls the muscles on the right side of the body. This part of the brain also controls speech and emotions as well as reading, thinking, and learning.

    The cerebellum, under the cerebrum at the back of the brain, controls balance and complex actions like walking and talking.

    The brain stem connects the brain with the spinal cord. It controls hunger and thirst and some of the most basic body functions, such as body temperature, blood pressure, and breathing.

    What Are The Parts Of The Brain

    The brain is made up of three main sections: the forebrain, the midbrain, and the hindbrain.

    The Forebrain

    The forebrain is the largest and most complex part of the brain. It consists of the cerebrum the area with all the folds and grooves typically seen in pictures of the brain as well as some other structures under it.

    The cerebrum contains the information that essentially makes us who we are: our intelligence, memory, personality, emotion, speech, and ability to feel and move. Specific areas of the cerebrum are in charge of processing these different types of information. These are called lobes, and there are four of them: the frontal, parietal, temporal, and occipital lobes.

    The cerebrum has right and left halves, called hemispheres. They’re connected in the middle by a band of nerve fibers that lets them communicate. These halves may look like mirror images of each other, but many scientists believe they have different functions:

    • The left side is considered the logical, analytical, objective side.
    • The right side is thought to be more intuitive, creative, and subjective.

    So when you’re balancing your checkbook, you’re using the left side. When you’re listening to music, you’re using the right side. It’s believed that some people are more “right-brained” or “left-brained” while others are more “whole-brained,” meaning they use both halves of their brain to the same degree.

    In the inner part of the forebrain sits the thalamus, hypothalamus, and :

    The Midbrain

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    Scientists Have Created An Artificial Sensory Nerve

    The system is able to collect information on applied pressure and convert it into electric impulses that can be integrated on a transistor.

    This transistor then releases electrical impulses in patterns consistent with those produced by neurons. The researchers were even able to use this system to move the muscles in a cockroachs leg.

    Does The Brain Have Nerves

    The Brain and Cranial Nerves Anatomy and Physiology

    Yes, the brain has nerves that come directly from the brain to the brain, these are called cranial nerves.

    Nerves are structures made up of bundles of neuronal fibers , located outside the central nervous system, which are responsible for conducting nerve impulses and communicating the nerve centers of the brain and spinal cord with the rest of the organs of the body, and vice versa.

    These fiber bundles are surrounded by a thin membrane, the perineurium, which surrounds the bundle of nerve fibers and in turn, the complete nerve formed by the union of several fascicles is covered by another structure, called the epineurium.

    As we will see later, some nerves originate from the spinal cord, while others originate from the brain. There are different types of nerves, being able to be sensitive, motor or mixed, and this will depend on the function that each one of them fulfills within our nervous system.

    But before delving into it, we will briefly see how the human nervous system works and what its characteristics are.

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    Where Is The Location Of The Cranial Nerves

    Two of your cranial nerve pairs originate in your cerebrum. The cerebrum is the largest portion of your brain that sits above your brainstem. These two pairs of cranial nerves include:

    • Olfactory nerves that affect your sense of smell.
    • Optic nerves that affect your ability to see.

    The other 10 pairs of cranial nerves start in your brainstem. Your brainstem connects your brain and spinal cord.

    Structure And Function Of The Spine

    The spine is made up of 26 bones divided into 5 sections. These bones surround and protect the spinal cord. This includes 24 vertebrae , the sacrum and the coccyx.

    Cervical region These are 7 vertebrae at the top of the spine that run from the base of the skull to the lowest part of the neck.

    Thoracic region These are 12 vertebrae that run from the shoulders to the middle of the back.

    Lumbar region These are 5 vertebrae that run from the middle of the back to the hips.

    Sacrum This is a large section of fused vertebrae at the base of the spine.

    Coccyx This is a small, thin section of fused vertebrae at the end of the spine.

    Between the vertebrae are the discs .

    Disc A layer of cartilage found between the vertebrae. Discs cushion and protect the vertebrae and spinal cord.

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