Central nervous system

In vertebrates, the central nervous system (CNS) is the part of the nervous system which is enclosed in the meninges. It contains the majority of the nervous system and consists of the brain (in vertebrates which have them), 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. [cite book
last = Maton
first = Anthea
authorlink =
coauthors = Jean Hopkins, Charles William McLaughlin, Susan Johnson, Maryanna Quon Warner, David LaHart, Jill D. Wright
title = Human Biology and Health
publisher = Prentice Hall
date = 1993
location = Englewood Cliffs, New Jersey, USA
pages = 132-144
url =
doi =
id =
isbn = 0-13-981176-1


Since the strong theoretical influence of cybernetics in the fifties, the central nervous system is conceived as a system devoted to information processing, where an appropriate motor output is computed as a response to a sensory input. Yet, many threads of research suggest that motor activity exists well before the maturation of the sensory systems and then, that the senses only influence behaviour without dictating it.


The telencephalon gives rise to 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.

Brain Prosencephalon Telencephalon
Lateral ventricles
Pituitary gland,
Pineal gland,
Third ventricle
Brain stem Mesencephalon
Cerebral peduncle,
Mesencephalic duct
Rhombencephalon Metencephalon
Myelencephalon Medulla oblongata
Spinal cord


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). [cite book
last = Hickman, Jr.
first = Cleveland P.
authorlink =
coauthors = Larry S. Roberts, Susan L. Keen, Allan Larson, Helen L'Anson, David J. Eisenhour
title = Integrated Princinples of Zoology: Fourteenth Edition
publisher = McGraw-Hill Higher Education
date = 2008
location = New York, NY, USA
pages = 733
url =
doi =
id =
isbn = 978-0-07-297004-3
] [cite book
last = Campbell
first = Neil A.
authorlink =
coauthors = Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
title = Biology: Eighth Edition
publisher = Pearson / Benjamin Cummings
date = 2008
location = San Francisco, CA, USA
pages = 1065
url =
doi =
id =
isbn = 978-0-8053-6844-4
] Their primitive brain, consisting of 2 fused anterior ganglia, and longitudinal nerve cords form the CNS and 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 those related to the planarian CNS, also exist in humans.cite journal |author=Katsuhiko Mineta, et al. |title=Origin and evolutionary process of the CNS elucidated by comparative genomics analysis of planarian ESTs|url=http://www.pnas.org/content/100/13/7666.full.pdf+html?sid=b2a914e7-5647-4ee2-835c-bc54c4927a98 |journal=PNAS |format = pdf |volume=100 |issue=13 |pages=7666–7671 |year=2003] Like planarians, vertebrates have a distinct CNS and PNS, though those of vertebreates display greater complexity.

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: while in the reptilian brain that region is only an appendix to the large olfactory bulb, it represents most of the volume of the mammalian 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.cite book
last = Bear
first = Mark F.
authorlink =
coauthors = Barry W. Connors, Michael A. Paradiso
title = Neuroscience: Exploring the Brain: Third Edition
publisher = Lippincott Williams & Wilkins
date = 2007
location = Philadelphia, PA, USA
pages = 196-199
url =
doi =
id =
isbn = 978-0-7817-6003-4
] The neocortex of monotremes (the duck-billed platypus and several species of spiny anteaters) as well as that of marsupials (such as kangaroos, koalas, opossums, wombats, Tasmanian devils, etc.) lack the convolutions - gyri and sulci - found in the neocortex of most placental mammals (eutherians).cite book
last = Kent
first = George C.
authorlink =
coauthors = Robert K. Carr
title = Comparative Anatomy of the Vertebrates: Ninth Edition
publisher = McGraw-Hill Higher Education
date = 2001
location = New York, NY, USA
pages = 408
url =
doi =
id =
isbn = 0-07-303869-5
] 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.198] In addition, rats lack convolutions in their neocortex (possibly also because they are small mammals), whereas the neocortex of cats has a moderate degree of convolutions, and that of humans exhibits quite extensive convolutions.199]
"See also:" Encephalization, Neocortex, Archicortex

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.

=See also=
* Glossary of anatomical terminology, definitions and abbreviations
* Central nervous system infection
* Neuroradiology


External links

* [http://www.sylvius.com Sylvius: 400+ structure neuroanatomical visual glossary]
* [http://primate-brain.org High-Resolution Cytoarchitectural Primate Brain Atlases]
* [http://www.marymt.edu/~psychol/brain.html Human Brains: A Learning Tool] .
* [http://www.humannervoussystem.info Explaining the human nervous system] .
* [http://www.backrack.co.uk/nervous_index.shtml Nervous System - Back Pain - Anatomy (info on nerve pairs)] .
* [http://www.mfi.ku.dk/ppaulev/content.htm Textbook in Medical Physiology And Pathophysiology, many links]
* [http://www.northland.cc.mn.us/biology/AP2Online/Fall2002/AP2PowerPoint/AP2Brainlecture_files/v3_document.htm Brain and Cranial Nerves, Anatomy and Physiology Lecture, Northland Community College]
* [http://www.sciencedaily.com/news/mind_brain/ Latest Research on the Brain and Central Nervous System] From [http://www.sciencedaily.com/ ScienceDaily]

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Look at other dictionaries:

  • central nervous system — n the part of the nervous system which in vertebrates consists of the brain and spinal cord, to which sensory impulses are transmitted and from which motor impulses pass out, and which supervises and coordinates the activity of the entire nervous …   Medical dictionary

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