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see spinal columnspinal 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.
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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.



A triangular bone, consisting in humans of five fused vertebrae, located below the last lumbar vertebra, above the coccyx, and between the hipbones.


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
References in periodicals archive ?
The results of our study, based on NOC indicators, suggest that the sacral region and the scapula regions are susceptible areas, since they showed high temperatures.
Having the legs slightly elevated by flexing the table at the hips of the patient prevents the patient slipping down the table and prevents pressure sores in the sacral region during hypotensive anesthesia.
This neural tube defect may occur anywhere along the vertebral column, but lumbar and sacral region are more common.
The work is the first to analyze elements of the cervical, thoracic, lumbar, and sacral regions of the vertebral column in Au.
It is used as an adjunct to fusion to treat degenerative slipped discs (spondylolisthesis) in the thoracic, lumbar or sacral regions when there is evidence of resulting neurologic impairment or in the case of a previous failed fusion (pseudarthrosis).
Dural ectasia is defined as an enlargement of the neural canal anywhere along the spinal column, usually in the lower lumbar and sacral regions.
Aplastic or hypoplastic vertebrae, hemivertebrae and butterfly vertebrae may be demonstrated at the thoracic, lumbar or sacral regions.
The generic way that level of injury is described is by the classifications "quadriplegia or tetraplegia," referring to injuries of the cervical regions, and "paraplegia," referring to injuries of the thoracic, lumbar, or sacral regions.