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brainstem

[breyn-stem] /ˈbreɪnˌstɛm/
noun
1.
the portion of the brain that is continuous with the spinal cord and comprises the medulla oblongata, pons, midbrain, and parts of the hypothalamus, functioning in the control of reflexes and such essential internal mechanisms as respiration and heartbeat.
Also, brain stem.
Origin
1875-1880
1875-80; brain + stem1
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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Examples from the web for brainstem
  • To be more precise, it's not the brain but the brainstem that regulates the heartbeat.
  • The team observed similar results using rat brainstem slices and cell-culture models.
  • In contrast, the sleepy subjects showed tighter coupling with basic alertness networks in the brainstem and thalamus.
  • The auras began a year or two following surgery for a tumor that was pressing on my brainstem.
  • Many areas are affected, including the part of the brainstem where cells that control eye movement are located.
  • For instance, the brainstem controls breathing and swallowing, among other things.
British Dictionary definitions for brainstem

brainstem

/ˈbreɪnˌstɛm/
noun
1.
the stalklike part of the brain consisting of the medulla oblongata, the midbrain, and the pons Varolii
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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brainstem in Science
brainstem
  (brān'stěm')   
The part of the vertebrate brain located at the base of the brain and made up of the medulla oblongata, pons, and midbrain. The brainstem controls and regulates vital body functions, including respiration, heart rate, and blood pressure. See also reticular formation.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for brainstem

brain stem

area at the base of the brain that lies between the deep structures of the cerebral hemispheres and the cervical spinal cord. It is divided into three sections: midbrain (mesencephalon), pons (metencephalon), and medulla oblongata (myelencephalon). The brainstem houses many of the control centres for vital body functions, such as swallowing, breathing, and vasomotor control. All of the cranial nerve nuclei, except those associated with olfaction and vision, are located in the brainstem, providing motor and sensory function to structures of the cranium, including the facial muscles, tongue, pharynx, and larynx, as well as supplying the senses of taste, equilibrium, and hearing. The brainstem also has nuclei important for sympathetic and parasympathetic autonomic functions. All efferent and afferent pathways between the cerebrum and cerebellum course through the brainstem, and many of them decussate, or cross, within this structure. Because of the important neural structures concentrated in this small portion of the nervous system, even very small lesions of the brainstem may have profound effects. Disorders involving the brainstem include trauma, tumours, strokes, infections, and demyelination (multiple sclerosis). Complete loss of brainstem function is regarded by some experts as equivalent to brain death.

Learn more about brain stem with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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