Any of the 33 approximately cylindrical bones that form the spine. There are 7 vertebrae in the cervical spine; 12 vertebrae in the thoracic spine; 5 vertebrae in the lumbar spine; 5 fused vertebrae in the sacrum; and 4 fused vertebrae in the coccyx. The top 24 vertebrae are separated by discs of cartilage (see disc, intervertebral). Each vertebra has a hole in the centre through which the spinal cord runs, and processes to which muscles are attached.


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