|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]|
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.
|sacrum (sā'krəm, sāk'rəm) Pronunciation Key
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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.
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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