Spinal cord


Spinal cord
The major column of nerve tissue that is connected to the brain, lies within the vertebral canal, and from which the spinal nerves emerge. The spinal cord and the brain constitute the central nervous system (CNS). The spinal cord consists of nerve fibers that transmit impulses to and from the brain. Like the brain, the spinal cord is covered by three connective-tissue envelopes called the meninges. The space between the outer and middle envelopes is filled with cerebrospinal fluid (CSF), a clear colorless fluid that cushions the spinal cord against jarring shock. Thirty-one pairs of spinal nerves originate in the spinal cord: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal. In the spinal cord, information about internal and external conditions travels up the ascending tracts to the brain. This information is processed by the brain and corresponding responses are induced by nerve impulses traveling down the descending tracts of the spinal cord to stimulate motor neurons or to initiate secretions by glands. The spinal cord is sometimes referred to simply as "the cord."

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spinal cord n the thick longitudinal cord of nervous tissue that in vertebrates extends along the back dorsal to the bodies of the vertebrae and is enclosed in the vertebral canal formed by their neural arches, is continuous anteriorly with the medulla oblongata, gives off at intervals pairs of spinal nerves to the various parts of the trunk and limbs, serves not only as a pathway for nervous impulses to and from the brain but as a center for carrying out and coordinating many reflex actions independently of the brain, and is composed largely of white matter arranged in columns and tracts of longitudinal fibers about a large central core of gray matter somewhat H-shaped in cross section and pierced centrally by a small longitudinal canal continuous with the ventricles of the brain called also medulla spinalis

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the portion of the central nervous system enclosed in the vertebral column, consisting of nerve cells and bundles of nerves connecting all parts of the body with the brain. It contains a core of grey matter surrounded by white matter. It is enveloped in three layers of membrane, the meninges, and extends from the medulla oblongata in the skull to the level of the second lumbar vertebra. From it arise 31 pairs of spinal nerves.

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medulla spinalis.

Medical dictionary. 2011.

Look at other dictionaries:

  • Spinal cord — Latin medulla spinalis The spinal cord nested in the vertebral column …   Wikipedia

  • Spinal cord — Spinal Spi nal, a. [L. spinalis, fr. spina the spine: cf. F. spinal. See {Spine}.] 1. (Anat.) Of, pertaining to, or in the region of, the backbone, or vertebral column; rachidian; vertebral. [1913 Webster] 2. Of or pertaining to a spine or spines …   The Collaborative International Dictionary of English

  • spinal cord — spinal cords N COUNT Your spinal cord is a thick cord of nerves inside your spine which connects your brain to nerves in all parts of your body …   English dictionary

  • spinal cord — n. the thick cord of nerve tissue of the central nervous system, extending down the spinal canal from the medulla oblongata …   English World dictionary

  • spinal cord — n the thick string of nerves enclosed in your ↑spine, by which messages are sent to and from your brain …   Dictionary of contemporary English

  • spinal cord — noun count the inner part of your SPINE that contains nerves going from your brain to the other parts of your body …   Usage of the words and phrases in modern English

  • spinal cord — ► NOUN ▪ the cylindrical bundle of nerve fibres which is enclosed in the spine and connected to the brain, with which it forms the central nervous system …   English terms dictionary

  • spinal cord — the cord of nerve tissue extending through the spinal canal of the spinal column. [1830 40] * * * In vertebrates, the body s major nerve tract. In humans it is about 18 in. (45 cm) long, running from the base of the brain through the vertebral… …   Universalium

  • spinal cord — noun a major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain; a long tubelike structure extending from the base of the brain through the vertebral canal to the upper lumbar region • Syn:… …   Useful english dictionary

  • spinal cord — UK / US noun [countable] Word forms spinal cord : singular spinal cord plural spinal cords medical the inner part of your spine that contains nerves going from your brain to the other parts of your body …   English dictionary


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