Central nervous system
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| Brain: Central nervous system | ||
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| A diagram showing the CNS: 1. Brain 2. Central nervous system (brain and spinal cord) 3. Spinal cord |
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| Latin | Pars centralis systematis nervosi; Systema nervosum centrale | |
The central nervous system (CNS) is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish. In vertebrates, the central nervous system is enclosed in the meninges. It contains the majority of the nervous system and consists of the brain and the spinal cord. Together with the peripheral nervous system it has a fundamental role in the control of behavior. The CNS is contained within the dorsal cavity, with the brain in the cranial cavity and the spinal cord in the spinal cavity. The brain is protected by the skull, while the spinal cord is protected by the vertebrae.[1]
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[edit] Neuroanatomy
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This section may be confusing or unclear to readers. Please help clarify the article; suggestions may be found on the talk page. (July 2009) |
During development, the telencephalon gives rise to[vague] the striatum (caudate nucleus and putamen), the hippocampus and the neocortex, its cavity becomes the lateral ventricles (first and second ventricles). The diencephalon give rise to the subthalamus, hypothalamus, thalamus and epithalamus, its cavity to the third ventricle. The mesencephalon gives rise to the tectum, pretectum, cerebral peduncle and its cavity develops into the mesencephalic duct or cerebral aqueduct. Finally, the rhombencephalon gives rise to the pons, the cerebellum and the medulla oblongata, its cavity becomes the fourth ventricle.
[edit] Evolution
Planarians, members of the phylum Platyhelminthes (flatworms), have the simplest, clearly defined delineation of a nervous system into a central nervous system (CNS) and a peripheral nervous system (PNS).[2] [3] Their primitive brain, consisting of 2 fused anterior ganglia, and longitudinal nerve cords form the CNS; the laterally projecting nerves form the PNS. A molecular study found that more than 95% of the 116 genes involved in the nervous system of planarians, which includes genes related to the CNS, also exist in humans.[4] Like planarians, vertebrates have a distinct CNS and PNS, though more complex than those of planarians.
The basic pattern of the CNS is highly conserved throughout the different species of vertebrates and during evolution. The major trend that can be observed is towards a progressive telencephalisation: the telecephalon of reptiles is only an appendix to the large olfactory bulb, while in mammals it makes up most of the volume of the CNS. In the human brain, the telencephalon covers most of the diencephalon and the mesencephalon. Indeed, the allometric study of brain size among different species shows a striking continuity from rats to whales, and allows us to complete the knowledge about the evolution of the CNS obtained through cranial endocasts.
Mammals – which appear in the fossil record after the first fishes, amphibians, and reptiles – are the only vertebrates to possess the evolutionarily recent, outermost part of the cerebral cortex known as the neocortex.[5] The neocortex of monotremes (the duck-billed platypus and several species of spiny anteaters) and of marsupials (such as kangaroos, koalas, opossums, wombats, and Tasmanian devils) lack the convolutions - gyri and sulci - found in the neocortex of most placental mammals (eutherians).[6] Within placental mammals, the size and complexity of the neocortex increased over time. The area of the neocortex of mice is only about 1/100 that of monkeys, and that of monkeys is only about 1/10 that of humans.[5] In addition, rats lack convolutions in their neocortex (possibly also because rats are small mammals), whereas cats have a moderate degree of convolutions, and humans have quite extensive convolutions.[5]
See also: Encephalization, Archicortex
[edit] Parts of the vertebrate CNS
In addition to the structures seen to the right in table above, a vast number of structures are present in the adult brain.
[edit] See also
- Glossary of anatomical terminology, definitions and abbreviations
- Central nervous system infection
- Neural development
- Neuroradiology
[edit] References
- ^ Maton, Anthea; Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. pp. 132–144. ISBN 0-13-981176-1.
- ^ Hickman, Jr., Cleveland P.; Larry S. Roberts, Susan L. Keen, Allan Larson, Helen L'Anson, David J. Eisenhour (2008). Integrated Princinples of Zoology: Fourteenth Edition. New York, NY, USA: McGraw-Hill Higher Education. pp. 733. ISBN 978-0-07-297004-3.
- ^ Campbell, Neil A.; Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson (2008). Biology: Eighth Edition. San Francisco, CA, USA: Pearson / Benjamin Cummings. pp. 1065. ISBN 978-0-8053-6844-4.
- ^ Katsuhiko Mineta, et al. (2003). "Origin and evolutionary process of the CNS elucidated by comparative genomics analysis of planarian ESTs" (pdf). PNAS 100 (13): 7666–7671. doi:. PMID 12802012. http://www.pnas.org/content/100/13/7666.full.pdf+html?sid=b2a914e7-5647-4ee2-835c-bc54c4927a98.
- ^ a b c Bear, Mark F.; Barry W. Connors, Michael A. Paradiso (2007). Neuroscience: Exploring the Brain: Third Edition. Philadelphia, PA, USA: Lippincott Williams & Wilkins. pp. 196–199. ISBN 978-0-7817-6003-4. http://books.google.com/books?id=75NgwLzueikC&printsec=frontcover&dq=neuroscience+exploring+the+brain.
- ^ Kent, George C.; Robert K. Carr (2001). Comparative Anatomy of the Vertebrates: Ninth Edition. New York, NY, USA: McGraw-Hill Higher Education. pp. 408. ISBN 0-07-303869-5.
[edit] External links
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Wikimedia Commons has media related to: Central nervous system |
- Sylvius: 400+ structure neuroanatomical visual glossary
- High-Resolution Cytoarchitectural Primate Brain Atlases
- Human Brains: A Learning Tool.
- Explaining the human nervous system.
- Nervous System - Back Pain - Anatomy (info on nerve pairs).
- Textbook in Medical Physiology And Pathophysiology, many links
- Brain and Cranial Nerves, Anatomy and Physiology Lecture, Northland Community College
- Latest Research on the Brain and Central Nervous System From ScienceDaily
- The Department of Neuroscience at Wikiversity
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