Pathophysiology


Corresponding regions of human and shark brain are shown. The shark brain is splayed out, while the human brain is more compact. The shark brain starts with the medulla, which is surrounded by various structures, and ends with the telencephalon. The cross-section of the human brain shows the medulla at the bottom surrounded by the same structures, with the telencephalon thickly coating the top of the brain.
Main anatomical regions of the vertebrate brain

[edit] Anatomy

From the brain-wikipedia article and for the purpose of understanding this article some summary notes about the brain and its different types of organic tissues will be provided.
When reading the human brain in the picture on the left, only a few of the areas are really of interest to us. The first type of tissue encountered beneath the skullbone in the intracranial cavity is actually not shown on this picture: the meninges. This is what is inflamed in meningitis.

[edit] Meninges

Human brains are surrounded by a system of connective tissue membranes called meninges that separate the skull from the brain. This three-layered covering is composed of (from the outside in) the dura mater ("hard mother"), arachnoid mater ("spidery mother"), and pia mater ("soft mother"). The arachnoid and pia are physically connected and thus often considered as a single layer, the pia-arachnoid. Below the arachnoid is the subarachnoid space which contains cerebrospinal fluid (CSF also called "liquor" in Latin), which circulates in the narrow spaces between cells and through cavities called ventricles, and serves 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. Tumors of the meninges are meningioma and are often benign neoplasms.

[edit] Brain matter

The brains of vertebrates (including humans) are made of very soft tissue, with a texture that has been compared to gelatin. Living brain tissue is pinkish on the outside and mostly white on the inside, with subtle variations in color. Three separate brain areas make up the majority of brain volume:
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.
Primary tumors of the glial cells are called Glioma and often are malignant by the time they are diagnosed. Editing Brain tumor

[edit] Spinal cord and other tissues

  • The pink area in picture is called the pons and is a specific region that consists of myelinated axons much like the spinal cord
  • The yellow region is the diencephalon (thalamus and hypothalamus) which consist also of neuron and glial cell tissue with the hypophysis (or pituitary gland) and pineal gland (which is glandular tissue) attached at the bottom; tumors of the pituitary and pineal gland are often benign neoplasms
  • The turquoise region or medulla oblongata is the end of the spinal cord and is composed mainly of neuron tissue enveloped in Schwann cells and meninges tissue. Our 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, responding to injury, etc.