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| {{Brain tumor}} | | {{Brain tumor}} |
| | {{CMG}}{{AE}}{{SR}} |
| | ==Overview== |
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| ==Pathophysiology== | | ==Pathophysiology== |
| [[File:Brain headBorder.jpg|thumb|The main areas of the brain and limbic system]]
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| ===Meninges=== | | ==Videos== |
| Human brains are surrounded by a system of [[connective tissue]] membranes called [[meninges]] that separate the [[Human brain|brain]] from the [[Human skull|skull]]. This three-layered covering is composed of (from the outside in) the [[dura mater]] ("hard mother"), [[arachnoid mater]] ("spidery mother"), and [[pia mater]] ("tender mother"). The arachnoid and pia are physically connected and thus often considered as a single layer, the pia-arachnoid. Between the arachnoid mater and the pia mater is the [[subarachnoid space]] which contains [[cerebrospinal fluid]] (CSF). This fluid circulates in the narrow spaces between cells and through the cavities in the brain called [[Ventricular system|ventricles]], to nourish, support, and protect the brain tissue. [[Blood vessels]] enter the [[central nervous system]] through the perivascular space above the pia mater. The cells in the blood vessel walls are joined tightly, forming the [[blood–brain barrier]] which protects the brain from [[toxins]] that might enter through the blood.
| | {{#ev:youtube|Ln7FtHJ6nyk}} |
| Tumors of the meninges are [[meningioma]]s and are often benign.
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| ===Brain matter===
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| The brains of humans and other [[vertebrates]] are composed of very soft tissue and a gelatin-like texture. Living brain tissue has a pink tint in color on the outside ([[grey matter]]), and nearly complete white on the inside ([[white matter]]), with subtle variations in color. Three separate brain areas make up most of the brain's volume:
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| *[[telencephalon]] (cerebral hemispheres or [[cerebrum]])
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| *[[mesencephalon]] (midbrain)
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| *[[cerebellum]]
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| These areas are composed of two broad classes of cells: [[neurons]] and [[glia]]. These two types are equally numerous in the brain as a whole, although [[glial cells]] outnumber [[neurons]] roughly 4 to 1 in the [[cerebral cortex]]. Glia come in several types, which perform a number of critical functions, including structural support, metabolic support, insulation, and guidance of development.
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| Primary tumors of the glial cells are called [[glioma]]s and often are malignant by the time they are diagnosed.
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| ===Spinal cord and other tissues===
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| The [[pons]] in the [[brainstem]] is a specific region that consists of myelinated axons much like the spinal cord.
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| The [[thalamus]] and [[hypothalamus]] of the [[diencephalon]] also consist of neuron and glial cell tissue with the hypophysis ([[pituitary gland]]) and [[pineal gland]] (which is glandular tissue) attached at the bottom; tumors of the [[pituitary]] and [[pineal gland]] are often benign.
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| The [[medulla oblongata]] is at the start of the spinal cord and is composed mainly of neuron tissue enveloped in [[Schwann cells]] and meninges tissue. The [[spinal cord]] is made up of bundles of these [[axons]]. Glial cells such as Schwann cells in the periphery or, within the cord itself, oligodendrocytes, wrap themselves around the axon, thus promoting faster transmission of electrical signals and also providing for general maintenance of the environment surrounding the cord, in part by shuttling different compounds around in response to injury or other stimulus.<ref>{{Cite web | url = https://en.wikipedia.org/w/index.php? | title = Brain tumor pathophysiology}}</ref>
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| ==References== | | ==References== |
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| {{Reflist|2}} | | {{Reflist|2}} |
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| [[Category:Primary care]]
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| [[Category:Disease]] | | [[Category:Disease]] |
| [[Category:Brain]] | | [[Category:Brain]] |
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