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The spine, or vertebral column, is composed of five main segments: the cervical, thoracic, and lumbar curvatures, the sacrum, and the coccyx. Each of these curvatures is composed of individual vertebrae, which provide structural support and protection for the spinal cord. There are twenty-four movable vertebrae in the spine; seven in the cervical curvature, twelve in the thoracic curvature, and five in the lumbar curvature. Additionally, the sacrum consists of five fused vertebrae and the coccyx is composed of three to five fused vertebrae.