sacra

sacrum

[sak-ruhm, sey-kruhm]
noun, plural sacra [sak-ruh, sey-kruh] . Anatomy.
a bone resulting from the fusion of two or more vertebrae between the lumbar and the coccygeal regions, in humans being composed usually of five fused vertebrae and forming the posterior wall of the pelvis.

Origin:
1745–55; < Late Latin (os) sacrum holy (bone), translation of Greek hieròn ostéon

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World English Dictionary
sacrum (ˈseɪkrəm, ˈsækrəm)
 
n , pl -cra
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
 
[C18: from Latin os sacrum holy bone, because it was used in sacrifices, from sacer holy]

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Etymonline
Word Origin & History

sacrum
"bone at the base of the spine," 1753, from L.L. os sacrum "sacred bone," from L. os "bone" + sacrum, neut. of sacer "sacred." Said to be so called because the bone was the part of animals that was offered in sacrifices. Translation of Gk. hieron osteon. But Gk. hieros also can mean "strong."
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

sacrum sa·crum (sā'krəm, sāk'rəm)
n. pl. sa·cra (sā'krə, sāk'rə)
The triangular segment of the spinal column that forms part of the pelvis and closes in the pelvic girdle posteriorly, is formed between the ages of 16 and 25 by the fusion of five originally separate sacral vertebrae, and articulates with the last lumbar vertebra, the coccyx, and the hipbone on either side.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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Science Dictionary
sacrum   (sā'krəm, sāk'rəm)  Pronunciation Key 


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Plural sacra
A triangular bone at the base of the spine, above the coccyx (tailbone), that forms the rear section of the pelvis. In humans it is made up of five vertebrae that fuse together by adulthood. See more at skeleton.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Britannica
Encyclopedia

sacra

wedge-shaped triangular bone at the base of the vertebral column, above the caudal (tail) vertebrae, or coccyx, that articulates (connects) with the pelvic girdle. In humans it is usually composed of five vertebrae, which fuse in early adulthood. The top of the first (uppermost) sacral vertebra articulates with the last (lowest) lumbar vertebra. The transverse processes of the first three sacral vertebrae are fused to form wide lateral wings, or alae, and articulate with the centre-back portions of the blades of the ilia to complete the pelvic girdle. The sacrum is held in place in this joint, which is called the sacroiliac, by a complex mesh of ligaments. Between the fused transverse processes of the lower sacral vertebrae, on each side, are a series of four openings (sacral foramina); the sacral nerves and blood vessels pass through these openings. A sacral canal running down through the centre of the sacrum represents the end of the vertebral canal; the functional spinal cord ends at about the level of the first sacral vertebra, but its continuation, the filum terminale, can be traced through the sacrum to the first coccygeal vertebra. See also vertebral column.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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