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spinal column

spinal column, bony column forming the main structural support of the skeleton of humans and other vertebrates, also known as the vertebral column or backbone. It consists of segments known as vertebrae linked by intervertebral disks and held together by ligaments. In human beings, the spinal column of the child contains more vertebrae than the adult, in whom a number become fused into two immovable bones, the sacrum and the coccyx, forming the back of the pelvis. The 24 movable vertebrae are the 7 cervical (neck), 12 thoracic (back of chest), and 5 lumbar (loin). The remaining vertebrae include 5 fused sacral, and between 3 and 5 fused caudal. Each vertebra has a somewhat cylindrical bony body (centrum), a number of winglike projections, and a bony arch. The bodies of the vertebrae form the strong but pliable supporting column of the skeleton. The arches are positioned so that the space they enclose is in effect a tube, the vertebral canal. It houses and protects the spinal cord, and within it the spinal fluid circulates. Ligaments and muscles are attached to various projections of the vertebrae. The 12 pairs of ribs that make up the front of the chest are linked to the thoracic vertebrae. The spine is subject to abnormal curvature, injury, infections, tumor formation, arthritic disorders, and puncture or slippage of the cartilage disks. Scoliosis is one relatively common disease which affects the spinal column. It involves moderate to severe lateral curvature of the spine, and, if not treated, may lead to serious deformities later in life.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



in terrestrial vertebrate animals and in man, one or several vertebrae that provide a strong connection between the iliac bones of the pelvis and the axial skeleton. The sacrum was formed as a result of the progressive development of the posterior extremities and their important role in locomotion. True sacral vertebrae (on which, if only in the embryo, there are sacral ribs that subsequently grow together with the transverse processes of the vertebrae) are distinguished from those that enter into the composition of the sacrum secondarily in order to reinforce it.

Present-day amphibians have one sacral vertebra, and reptiles have two (fossil forms often had more). In birds with two true sacral vertebrae, the anterior caudal, all the lumbar, and one or two of the last thoracic vertebrae are grown together to form a single bone, the synsacrum, out of ten or 12 vertebrae. In mammals, up to ten vertebrae are grown together in the sacrum; only one or two are true sacral vertebrae, and the rest are the anterior caudal vertebrae. When there is secondary disappearance of the posterior extremities (for example, in snakes and whales), the sacral region of the spine loses its function and is not differentiated.

In humans the sacrum is formed of five vertebrae, which merge in adults into a single sacral bone (os sacrum), which posteriorly closes the pelvic girdle.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


A triangular bone, consisting in humans of five fused vertebrae, located below the last lumbar vertebra, above the coccyx, and between the hipbones.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


1. (in man) the large wedge-shaped bone, consisting of five fused vertebrae, in the lower part of the back
2. the corresponding part in some other vertebrates
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
In view of chronic pain and non-relief of symptoms with medical and physiotherapy treatment, surgical excision of the pseudo-articulation of the left L5 transverse process with the sacrum was done (Figure 2).
Clinical Anatomy of the Lumbar Spine and Sacrum. 4th ed.
Samples with complete ossification of the growth plates and free from major structural damage were selected for measurements after identification of LSTV characteristics of accessory articulation on the ala of the sacrum, additional/partial segments (> 5 = sacralization) or less/partial sacral segments (< 5 = lumbarization).
The later reimplantation of the resected sacrum after extracorporeal radiation is also possible, but this procedure is associated with an increased risk of infection [10-18].
Thus, understanding the morphological variations of sacrum and coccyx is imperative.
Concretamente, siempre segun la autora de la edicion, el Carmen sacrum habria sido compuesto por Proba alrededor del ano 362, unos diez anos despues de su conversion, lo que justifica que en el poema haya una mezcla de ortodoxia doctrinal con su personal idiosincrasia.
Hauzeur, "Stress fracture of the sacrum," American Journal of Sports Medicine, vol.
Strong ligaments between the sacrum and the ilium permit hardly any movement of the joint.
She examines neck injury, the pelvis and sacrum, back pain, and the chest, beginning with a discussion of their anatomy and what could be functioning improperly.
Holiday accident leaves singer with a fractured sacrum, leading her to cancel tour and recording of new album with Dr Craig Lennox MARIANNE Faithfull has cancelled her tour and postponed recording her new album because she has fractured her back.
They compared measurements of its lumbar vertebrae (lower back) and sacrum (a triangular bone at the base of the spine) to those of modern humans, fossil hominins (extinct bipedal human ancestors), and a sample of mammals that commonly move around in trees, including apes, sloths and an extinct lemur.