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1. Brain
2. Central nervous system
(brain and spinal cord)
3. Spinal cord
The central nervous system (CNS) of the vertebrate nervous system which is enclosed in meninges. It contains the majority of the nervous system, and consists of the brain (in vertebrates which have brains), 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 within the cranial cavity, and the spinal cord in the spinal cavity. The brain is also protected by the skull, and the spinal cord is, in vertebrates, also protected by the vertebrae. [1]
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Function
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.
Development
In the developing fetus, the CNS originates from the neural plate, a specialised region of the ectoderm, the most external of the three embryonic layers. During embryonic development, the neural plate folds and forms the neural tube. The internal cavity of the neural tube will give rise to the ventricular system. The regions of the neural tube will differentiate progressively into transversal systems. First, the whole neural tube will differentiate into its two major subdivisions: brain (rostral/cephalic) and spinal cord (caudal). Consecutively, the brain will differentiate into prosencephalon and brainstem. Later, the prosencephalon will subdivide into telencephalon and diencephalon, and the brainstem into mesencephalon and rhombencephalon.
Neuroanatomy
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.
Evolution
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.
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
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, 132-144. ISBN 0-13-981176-1.
External links
- 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
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Wikipedia content modification information:
- This page was last modified on 8 May 2008, at 22:32.
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