Vertebra

Vertebrae (singular: vertebra) are the individual bones that make up the vertebral column (aka spine) — a flexuous and flexible column.

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There are thirty-three (33) vertebrae in humans, including the five that are fused to form the sacrum (the others are separated by intervertebral discs) and the four coccygeal bones which form the tailbone.

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The upper three regions comprise the remaining 24, and are grouped under the names cervical (7 vertebrae), thoracic (12 vertebrae) and lumbar (5 vertebrae), according to the regions they occupy.

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This number is sometimes increased by an additional vertebra in one region, or it may be diminished in one region, the deficiency often being supplied by an additional vertebra in another.

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The number of cervical vertebrae is, however, very rarely increased or diminished.

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With the exception of the first and second cervical, the true or movable vertebrae (the upper three regions) present certain common characteristics which are best studied by examining one from the middle of the thoracic region.

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Bones: REDIRECT Bone...

Vertebral column: The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen....

Sacrum: The sacrum (os sacrum) is a large, triangular bone at the base of the vertebral column and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. Its upper part or base articulates with the last lumbar vertebra, its apex with the coccyx. It is ...