The CNS consists of the brain and spinal cord, i beg your pardon are situated in the dorsal human body cavity. The mind is surrounding by the cranium, and also the spinal cord is safeguarded by the vertebrae. The brain is continuous with the spinal cord at the foramen magnum. In addition to bone, the CNS is surrounded by connective organization membranes, referred to as meninges, and also by cerebrospinal fluid.

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There are three class of meninges approximately the brain and spinal cord. The external layer, the dura mater, is difficult white fibrous connective tissue. The middle layer that meninges is arachnoid, which each other a cobweb in appearance, is a slim layer with many threadlike strands that attach it come the innermost layer. The space under the arachnoid, the subarachnoid space, is filled through cerebrospinal fluid and also contains blood vessels. The pia mater is the innermost class of meninges. This thin, breakable membrane is strictly bound come the surface ar of the mind and spinal cord and cannot be dissected far without damaging the surface.

Meningiomas space tumors that the nerve tissue extending the brain and spinal cord. Return meningiomas are usually not likely to spread, physicians frequently treat them together though they were malignant to treat symptoms that may develop when a tumor applies pressure come the brain.


The mind is split into the cerebrum, diencephalons, brain stem, and also cerebellum.


The largest and most obvious section of the mind is the cerebrum, which is divided by a deep longitudinal fissure right into two cerebral hemispheres. The two hemispheres room two separate entities however are linked by an arching band of white fibers, dubbed the body callosum that gives a communication pathway in between the two halves.

Each cerebral hemisphere is split into five lobes, 4 of which have the exact same name as the bone end them: the fontal lobe, the parietal lobe, the occipital lobe, and also the temporal lobe. A 5th lobe, the insula or Island that Reil, lies deep in ~ the lateral sulcus.


The diencephalons is centrally located and is practically surrounded through the cerebral hemispheres. It includes the thalamus, hypothalamus, and also epithalamus. The thalamus, around 80 percent that the diencephalons, is composed of two oval masses that gray matter that serve as relay stations because that sensory impulses, except for the sense of smell, going to the cerebral cortex. The hypothalamus is a small an ar below the thalamus, i m sorry plays a crucial role in maintaining homeostasis because it regulates numerous visceral activities. The epithalamus is the many dorsal part of the diencephalons. This tiny gland is affiliated with the onset of puberty and rhythmic cycles in the body. The is like a organic clock.

Brain Stem

The brain stem is the an ar between the diencephalons and the spinal cord. It consists of 3 parts: midbrain, pons, and medulla oblongata. The midbrain is the most superior portion of the brain stem. The pons is the bulging middle section of the brain stem. This region primarily is composed of nerve fibers that kind conduction tracts in between the higher brain centers and also spinal cord. The medulla oblongata, or merely medulla, extends inferiorly indigenous the pons. It is consistent with the spinal cord in ~ the foramen magnum. Every the ascending (sensory) and descending (motor) nerve fibers connecting the brain and spinal cord pass through the medulla.


The cerebellum, the second largest portion of the brain, is located below the occipital lobes the the cerebrum. Three paired bundles of myelinated nerve fibers, dubbed cerebellar peduncles, type communication pathways between the cerebellum and also other components of the central nervous system.

Ventricles and Cerebrospinal Fluid

A series of interconnected, fluid-filled caries are found within the brain. This cavities space the ventricles the the brain, and also the liquid is cerebrospinal liquid (CSF).

Spinal Cord

The spinal cord extends indigenous the foramen magnum at the basic of the skull to the level of the an initial lumbar vertebra. The cord is constant with the medulla oblongata in ~ the foramen magnum. Like the brain, the spinal cord is surrounding by bone, meninges, and cerebrospinal fluid.

The spinal cord is split into 31 segments through each segment offering rise to a pair that spinal nerves. In ~ the distal end of the cord, plenty of spinal nerves extend beyond the conus medullaris to kind a arsenal that each other a horse"s tail. This is the cauda equina. In overcome section, the spinal cord shows up oval in shape.

The spinal cord has two key functions:

Serving as a conduction pathway for impulses walk to and also from the brain. Sensory impulses take trip to the mind on ascending tracts in the cord. Motor impulses travel on diminish tracts.Serving together a reflex center. The reflex arc is the sensible unit that the concerned system. Reflexes room responses to stimuli that do not require aware thought and also consequently, they occur much more quickly than reactions that call for thought processes. For example, through the tap the money reflex, the reflex activity withdraws the affected part before friend are mindful of the pain. Numerous reflexes are mediated in the spinal cord there is no going come the higher mind centers.

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Brain Tumor

Glioma refers to tumors the arise from the support cells of the brain. These cells are referred to as glial cells. These tumors include the astrocytomas, ependymomas and oligodendrogliomas. This tumors are the most typical primary mind tumors.