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Central Nervous System (CNS) DefinitionDamage to the brain can be caused by many things, for example, trauma and ALS.
Brain and Cerebrum LocationThe cerebrum is the largest part of the brain and controls voluntary actions, speech, senses, thought, and memory. The surface of the cerebral cortex has grooves or infoldings (called sulci), the largest of which are termed fissures. Some fissures separate lobes. The convolutions of the cortex give it a wormy appearance. Each convolution is delimited by two sulci and is also called a gyrus (gyri in plural). The cerebrum is divided into two halves, known as the right and left hemispheres. A mass of fibers called the corpus callosum links the hemispheres. The right hemisphere controls voluntary limb movements on the left side of the body, and the left hemisphere controls voluntary limb movements on the right side of the body. Almost every person has one dominant hemisphere. Each hemisphere is divided into four lobes, or areas, which are interconnected.
The cortex, also called gray matter, is the most external layer of the brain and predominantly contains neuronal bodies (the part of the neurons where the DNA-containing cell nucleus is located). The gray matter participates actively in the storage and processing of information. An isolated clump of nerve cell bodies in the gray matter is termed a nucleus (to be differentiated from a cell nucleus). The cells in the gray matter extend their projections, called axons, to other areas of the brain. Fibers that leave the cortex to conduct impulses toward other areas are termed efferent fibers, and fibers that approach the cortex from other areas of the nervous system are termed afferent (nerves or pathways). Fibers that go from the motor cortex to the brainstem (for example, the pons) or the spinal cord receive a name that generally reflects the connections (that is, corticopontine tract for the former and corticospinal tract for the latter). Axons are surrounded in their course outside the gray matter by myelin, which has a glistening whitish appearance and thus gives rise to the term white matter. Cortical areas receive their names according to their general function or lobe name. If in charge of motor function, the area is called the motor cortex. If in charge of sensory function, the area is called a sensory or somesthetic cortex. The calcarine or visual cortex is located in the occipital lobe (also termed occipital cortex) and receives visual input. The auditory cortex, localized in the temporal lobe, processes sounds or verbal input. Knowledge of the anatomical projection of fibers of the different tracts and the relative representation of body regions in the cortex often enables doctors to correctly locate an injury and its relative size, sometimes with great precision. QUESTIONWhat kind of disease is multiple sclerosis? See AnswerCentral Structures of the BrainThe central structures of the brain include the thalamus, hypothalamus, and pituitary gland. The hippocampus is located in the temporal lobe but participates in the processing of memory and emotions and is interconnected with central structures. Other structures are the basal ganglia, which are made up of gray matter and include the amygdala (localized in the temporal lobe), the caudate nucleus, and the lenticular nucleus (putamen and globus pallidus). Because the caudate and putamen are structurally similar, neuropathologists have coined for them the collective term striatum.
Base of the BrainThe base of the brain contains the cerebellum and the brainstem. These structures serve complex functions. Below is a simplified version of these roles:
Peripheral Nervous System FunctionNerve fibers that exit the brainstem and spinal cord become part of the peripheral nervous system. Cranial nerves exit the brainstem and function as peripheral nervous system mediators of many functions, including eye movements, facial strength and sensation, hearing, and taste. The optic nerve is considered a cranial nerve but it is generally affected in a disease of the central nervous system known as multiple sclerosis, and, for this and other reasons, it is thought to represent an extension of the central nervous system apparatus that controls vision. In fact, doctors can diagnose inflammation of the head of the optic nerve by using an ophthalmoscope, as if the person's eyes were a window into the central nervous system. Nerve roots leave the spinal cord to the exit point between two vertebrae and are named according to the spinal cord segment from which they arise (a cervical eight nerve root arises from cervical spinal cord segment eight). Nerve roots are located anterior with relation to the cord if efferent (for example, carrying input toward limbs) or posterior if afferent (for example, to spinal cord). Fibers that carry motor input to limbs and fibers that bring sensory information from the limbs to the spinal cord grow together to form a mixed (motor and sensory) peripheral nerve. Some lumbar and all sacral nerve roots take a long route downward in the spinal canal before they exit in a bundle that resembles a horse's tail, hence its name, cauda equina. The spinal cord is also covered, like the brain, by the pia matter and the arachnoid membranes. The cerebrospinal fluid circulates around the pia and below the outer arachnoid, and this space is also termed the subarachnoid space. The roots of the cauda equina and the rootlets that make up the nerve roots from higher segments are bathed in cerebrospinal fluid. The dura surrounds the pia-arachnoid of the spinal cord, as it does for the brain. The neuroanatomical basis for multiple brain functions is oversimplified in the above summary. A good example is the neuroanatomical substrate for memory function. Damage to multiple areas of the brain can affect memory. These include structures such as the frontal and temporal lobes, the thalamus, the cerebellum, the putamen, mamillary bodies and fornix, and a convolution above the corpus callosum known as the cingulate gyrus. These structures are variably involved in complex processes such as the storing, processing, or retrieval of memories. Spinal Cord NervesPicture of the The Spinal Cord Parts The spinal cord is an extension of the brain and is surrounded by the vertebral bodies that form the spinal column (see Multimedia File 3). The central structures of the spinal cord are made up of gray matter (nerve cell bodies), and the external or surrounding tissues are made up of white matter. Within the spinal cord are 30 segments that belong to 4 sections (cervical, thoracic, lumbar, sacral), based on their location:
SLIDESHOWWhat Is Multiple Sclerosis? MS Symptoms, Causes, Diagnosis See SlideshowFromWhat Is Multiple Sclerosis (MS)?Multiple sclerosis or MS is an autoimmune disorder that happens when your body's immune system attacks the covering (myelin sheath) that surrounds the nerves of the central nervous system (CNS). Doctors and researchers don't know exactly a person gets MS, but they believe it's related to genetics, acquired (you get it from an infection, etc.), or from the environment. References REFERENCE: Chawla, J, MD, et al. "Central Nervous System Anatomy." Medscape. Updated:
June 28, 2016. What are the 7 main parts of the central nervous system?The central nervous system (defined as the brain and spinal cord) is usually considered to have seven basic parts: the spinal cord, the medulla, the pons, the cerebellum, the midbrain, the diencephalon, and the cerebral hemispheres (Figure 1.10; see also Figure 1.8).
What are the main 3 parts of the central nervous system?The central nervous system (CNS) is made up of the brain, cerebellum and the spinal cord.. Nerves make up the peripheral nervous system (PNS), which works to send signals to and from the CNS, the body's organs, muscles, and senses.. What are the 4 main functions of the central nervous system?The four main functions of the nervous system are:. Control of body's internal environment to maintain 'homeostasis' An example of this is the regulation of body temperature. ... . Programming of spinal cord reflexes. An example of this is the stretch reflex. ... . Memory and learning. ... . Voluntary control of movement.. What are the 5 main functions of the central nervous system?Your nervous system is your body's command center. Originating from your brain, it controls your movements, thoughts and automatic responses to the world around you. It also controls other body systems and processes, such as digestion, breathing and sexual development (puberty).
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