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What Consists Of The Brain And Spinal Cord

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The Central Nervous System: The Brain and Spinal Cord

Some of the most obvious signs you are being spied on include: Someone seems to always be bumping into you in public. As if they always know when and where to find you. During divorce or separation, your ex-partner knows more details than they should about your activities, finances, or other details.

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Central nervous system : a part of the nervous system which includes the brain and spinal cord.

Parasympathetic nervous system: the part of your nervous system that unconsciously controls your organs and glands when your body is at rest.

Peripheral nervous system : a part of the nervous system which includes all the nerves outside of the brain and spinal cord.

Sympathetic nervous system: The part of your nervous system that unconsciously controls your organs and glands when youre excited or frightened.

Neurons In Nervous Tissue Relay Rapid

All nervous tissue, from the brain to the spinal cord to the furthest nerve branch, includes cells called neurons. Neurons are charged cells: they conduct electrical signals to pass information through the body. A typical neuron consists of a cell body, dendrites, and an axon with an axon terminal. The dendrites receive signals from body tissues or other neurons and pass them into the cell body. If an outgoing signal is produced, it zips down the axon to the axon terminal and passes to the next neuron or target cell. This conductive capability sends information up and down nerve pathways and through the central nervous system at incredible speed. Some 100 billion neurons give the brain its awesome processing power.

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Functions Of The Cranial Nerves

Each of the 12 cranial nerves has a specific function within the nervous system.

  • The olfactory nerve carries scent information to the brain from the olfactory epithelium in the roof of the nasal cavity.
  • The optic nerve carries visual information from the eyes to the brain.
  • Oculomotor, trochlear, and abducens nerves all work together to allow the brain to control the movement and focus of the eyes. The trigeminal nerve carries sensations from the face and innervates the muscles of mastication.
  • The facial nerve innervates the muscles of the face to make facial expressions and carries taste information from the anterior 2/3 of the tongue.
  • The vestibulocochlear nerve conducts auditory and balance information from the ears to the brain.
  • The glossopharyngeal nerve carries taste information from the posterior 1/3 of the tongue and assists in swallowing.
  • The vagus nerve , sometimes called the wandering nerve due to the fact that it innervates many different areas, wanders through the head, neck, and torso. It carries information about the condition of the vital organs to the brain, delivers motor signals to control speech and delivers parasympathetic signals to many organs.
  • The accessory nerve controls the movements of the shoulders and neck.
  • The hypoglossal nerve moves the tongue for speech and swallowing.

Grey And White Matter

The spinal cord

In terms of tissue, the CNS is divided into grey matter and white matter. Grey matter comprises neuron cell bodies and their dendrites, glial cells, and capillaries. Because of the abundant blood supply of this tissue, its actually more pink-coloured than grey.

In the brain, grey matter is mainly found in the outer layers, while in the spinal cord it forms the core butterfly shape.

White matter refers to the areas of the CNS which host the majority of axons, the long cords that extend from neurons. Most axons are coated in myelin – a white, fatty insulating cover that helps nerve signals travel quickly and reliably. In the brain, white matter is buried under the grey surface, carrying signals across different parts of the brain. In the spinal cord, white matter is the external layer surrounding the grey core.

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White Matter Grey Matter And Spinal Tracts

Together, the gray and white matter of your brain and spinal cord help form spinal tracts. These pathways send nerve signals from your brain to the rest of your body. Knowing the most common tracts can help you discern the source of your injury. Those tracts include:

  • Posterior tracts: These tracts, located at the back of your spinal cord, convey information from your skin about pressure, touch, and pain. They also help you position your body and space, so you can move according to your surroundings.
  • Spinothalamic tracts: These sensory tracts tell your brain about your body’s temperature and pain level.
  • Corticospinal tracts: These motor tracts send nerve signals from the brain, down the spinal cord, and into various skeletal muscles, enabling you to move.

Remember, being an informed patient can help you ask intelligent questions and select the best treatment options, so if you don’t understand what your doctor tells you about gray or white matter in the brain, don’t be afraid to speak up. Keep asking questions until it all makes sense every traumatic brain or spinal cord injury survivor has to learn to be a strong advocate and asking pointed questions can help you begin mastering the art of advocacy.

What Are The Parts Of The Central Nervous System

The nervous system is made up of basic units called neurons. The neurons are arranged in networks that carry electrical or chemical messages to and from the brain.

The tissue of the central nervous system is made up of grey matter and white matter. Grey matter is made up of neurons, cells and blood vessels. White matter is made up of axons, which are long cords that extend from the neurons. They are coated in myelin, which is a fatty insulation.

The brain and spinal cord are protected from damage by a clear liquid called cerebrospinal fluid, 3 layers of membranes called the meninges, and the hard bones of the skull and backbone.

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How Does An Mri Scan Work

The MRI machine is a large, cylindrical machine that createsa strong magnetic field around the patient. The magnetic field, along withradio waves, alters the hydrogen atoms’ natural alignment in the body.Pulses of radio waves sent from a scanner knock the nuclei in your atomsout of their normal position. As the nuclei realign back into properposition, the nuclei send out radio signals. These signals are received bya computer that analyzes and converts them into a two-dimensional image of the body structure or organ being examined.

Magnetic resonance may be used instead ofcomputed tomography in situations where organs or soft tissue are being studied, because MRI isbetter at telling the difference between normal and abnormal soft tissue.

New uses and indications for MRI have contributed to the development ofadditional magnetic resonance technology.Magnetic resonance angiography is a new procedure used to evaluate blood flow through arteries in anoninvasive manner. MRA can also be used todetectintracranial aneurysmsand vascular malformations .

Magnetic resonance spectroscopy is another noninvasive procedure usedto assess chemical abnormalities in body tissues, such as the brain. MRSmay be used to assess disorders such asHIV infection of the brain,stroke,head injury, coma,Alzheimer’s disease, tumors, andmultiple sclerosis.

Expert Review And References

Spinal Cord and Meninges – Human Brain Anatomy
  • Detailed guide: CNS tumors in children. American Cancer Society. American Cancer Society . Atlanta, GA: American Cancer Society 2008.
  • American Society of Clinical Oncology. Central Nervous System Tumors – Childhood – Overview. 2014.
  • Central nervous system – childhood. American Society of Clinical Oncology . People Living with Cancer. Alexandria, VA.: American Society of Clinical Oncology 2008.
  • Brain tumours in children. Cancerbackup. Cancerbackup. London, UK: Cancerbackup 2008.
  • Brain tumours. Hospital for Sick Children. AboutKidsHealth. Toronto, ON: Hospital for Sick Children 2004.
  • The Hospital for Sick Children . AboutKidsHealth: An Overview of the Brain. 2009: .

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Everyday Connections The Myth Of Left Brain/right Brain

There is a persistent myth that people are right-brained or left-brained, which is an oversimplification of an important concept about the cerebral hemispheres. There is some lateralization of function, in which the left side of the brain is devoted to language function and the right side is devoted to spatial and nonverbal reasoning. Whereas these functions are predominantly associated with those sides of the brain, there is no monopoly by either side on these functions. Many pervasive functions, such as language, are distributed globally around the cerebrum.

Some of the support for this misconception has come from studies of split brains. A drastic way to deal with a rare and devastating neurological condition is to separate the two hemispheres of the brain. After sectioning the corpus callosum, a split-brained patient will have trouble producing verbal responses on the basis of sensory information processed on the right side of the cerebrum, leading to the idea that the left side is responsible for language function.

Difference From The Peripheral Nervous System

This differentiates the CNS from the PNS, which consists of neurons, axons, and Schwann cells. Oligodendrocytes and Schwann cells have similar functions in the CNS and PNS, respectively. Both act to add myelin sheaths to the axons, which acts as a form of insulation allowing for better and faster proliferation of electrical signals along the nerves. Axons in the CNS are often very short, barely a few millimeters, and do not need the same degree of isolation as peripheral nerves. Some peripheral nerves can be over 1 meter in length, such as the nerves to the big toe. To ensure signals move at sufficient speed, myelination is needed.

The way in which the Schwann cells and oligodendrocytes myelinate nerves differ. A Schwann cell usually myelinates a single axon, completely surrounding it. Sometimes, they may myelinate many axons, especially when in areas of short axons. Oligodendrocytes usually myelinate several axons. They do this by sending out thin projections of their cell membrane, which envelop and enclose the axon.

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Reflexes And Other Stimulus

The simplest type of neural circuit is a reflex arc, which begins with a sensory input and ends with a motor output, passing through a sequence of neurons in between. For example, consider the “withdrawal reflex” causing the hand to jerk back after a hot stove is touched. The circuit begins with sensory receptors in the skin that are activated by harmful levels of heat: a special type of molecular structure embedded in the membrane causes heat to change the electrical field across the membrane. If the change in electrical potential is large enough, it evokes an action potential, which is transmitted along the axon of the receptor cell, into the spinal cord. There the axon makes excitatory synaptic contacts with other cells, some of which project to the same region of the spinal cord, others projecting into the brain. One target is a set of spinal interneurons that project to motor neurons controlling the arm muscles. The interneurons excite the motor neurons, and if the excitation is strong enough, some of the motor neurons generate action potentials, which travel down their axons to the point where they make excitatory synaptic contacts with muscle cells. The excitatory signals induce contraction of the muscle cells, which causes the joint angles in the arm to change, pulling the arm away.

Cerebrum The Cerebrum Is The Largest Part Of The Brain It Is Divided Into 2 Halves Called The Left And Right Cerebral Hemispheres The 2 Hemispheres Are Connected By A Bridge Of Nerve Fibres Called The Corpus Callosum The Right Half Of The Cerebrum Controls The Left Side Of The Body The Left Half Of The Cerebrum Controls The Right Side Of The Body The Cerebral Cortex Is The Outer Folded Part Of The Brain It Is Also Called The Grey Matter The Cerebral Cortex Is Mostly Made Up Of The Cell Bodies And Dendrites Of Nerve Cells Cell Bodies Contain The Nucleus And Other Main Parts Of The Cell Dendrites Are The Short Branching Fibres That Receive Signals From Other Nerve Cells The Inner Part Of The Cerebrum Is Called The White Matter It Is Mostly Made Up Of The Long Fibres Of A Nerve Cell That Send Signals To And From The Brain To The Rest Of The Body The Fatty Coating That Surrounds Axons Gives This Part Of The Brain A Whitish Appearance Each Hemisphere Is Divided Into 4 Sections Called Lobes These Include The Frontal Parietal Temporal And Occipital Lobes

Meninges and Cerebrospinal Fluid (Gross Anatomy of the ...

Each lobe has different functions:

The frontal lobe controls movement, speech, behaviour, memory, emotions and intellectual functions, such as thought processes, reasoning, problem solving, decision-making and planning.

The parietal lobe controls sensations, such as touch, pressure, pain and temperature. It also controls the understanding of size, shape and direction .

The temporal lobe controls hearing, memory and emotions. The dominant temporal lobe also controls speech.

The occipital lobe controls vision.

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Why Cant The Central Nervous System Repair Itself After Injury

Many organs and tissues in the body can recover after injury without intervention. Unfortunately, some cells of the central nervous system are so specialized that they cannot divide and create new cells. As a result, recovery from a brain or spinal cord injury is much more difficult.

The complexity of the central nervous system makes the formation of the right connections between brain and spinal cord cells very difficult. It is a huge challenge for scientists to recreate the central nervous system that existed before the injury.

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Neural Circuits And Systems

The basic neuronal function of sending signals to other cells includes a capability for neurons to exchange signals with each other. Networks formed by interconnected groups of neurons are capable of a wide variety of functions, including feature detection, pattern generation, and timing . In fact, it is difficult to assign limits to the types of information processing that can be carried out by neural networks: Warren McCulloch and Walter Pitts proved in 1943 that even artificial neural networks formed from a greatly simplified mathematical abstraction of a neuron are capable of universal computation. Given that individual neurons can generate complex temporal patterns of activity independently, the range of capabilities possible for even small groups of neurons are beyond current understanding.

Treatise of Man

Can You Survive Without A Spinal Cord

Central Nervous system (brain and spinal cord) and Peripheral Nervous System( somatic and autonomic)

The spinal cord is a column of nerves that connects your brain with the rest of your body, allowing you to control your movements. Without a spinal cord, you could not move any part of your body, and your organs could not function. This is why keeping your spine healthy is vital if you want to live an active life.

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Spinal Cord And Brain Stem

A sensory pathway that carries peripheral sensations to the brain is referred to as an ascending pathway, or ascending tract. The various sensory modalities each follow specific pathways through the CNS. Tactile and other somatosensory stimuli activate receptors in the skin, muscles, tendons, and joints throughout the entire body. However, the somatosensory pathways are divided into two separate systems on the basis of the location of the receptor neurons. Somatosensory stimuli from below the neck pass along the sensory pathways of the spinal cord, whereas somatosensory stimuli from the head and neck travel through the cranial nervesâspecifically, the trigeminal system.

The dorsal column system and the spinothalamic tract are two major pathways that bring sensory information to the brain . The sensory pathways in each of these systems are composed of three successive neurons.

Figure 14.5.1 â Ascending Sensory Pathways of the Spinal Cord:

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What Is The Central Nervous System

The central nervous system controls most functions of the body and mind. It consists of two parts: the brain and the spinal cord.

The brain is the center of our thoughts, the interpreter of our external environment, and the origin of control over body movement. Like a central computer, it interprets information from our eyes , ears , nose , tongue , and skin , as well as from internal organs such as the stomach.

The spinal cord is the highway for communication between the body and the brain. When the spinal cord is injured, the exchange of information between the brain and other parts of the body is disrupted.

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Cerebrum And Cerebral Cortex

The cerebrum makes up most of the brain. It is found in the cranial vault. The cerebrum consists of two cerebral hemispheres and five lobes. All lobes are named according to the cranial bones on which they lean: frontal, parietal, temporal, occipital and insular lobes. The insular lobe is hidden just beneath the frontal, temporal, and parietal lobes. Insula means island, which the insular lobe is indeedan isle of gray matter hidden under the surface of the cerebrum.

Youll probably encounter the termlimbic lobe as well, but this is not an actual lobe. Rather its a functional group of interconnected regions of the brain which together control emotions, memory and spatial perception. The cerebrum together with the hippocampus, amygdala, olfactory bulb, and basal ganglia comprise the telencephalon.

The most superficial layer of the cerebrum is the cerebral cortex. It is a layer of grey matter which displays numerous folds , can be categorization structurally or functionally , and is home to areas such as the primary motor cortex and the primary somatosensory cortex, both of which house a homunculus.

White matter connections extend between the cerebral cortex grey matter to other parts of the same cerebral hemisphere to the opposite hemisphere and to structures outside the cortex . Learn more about cerebral cortex and its structure with our study units:

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