The vertebral column (also known as backbone, spine, spinal column, latin: columna vertebralis) is a sequence of bones called the vertebrae separated from each other by intervertebral discs. The vertebral column forms the main axis of the human body.
The human spine is flexible and it supports the head, neck and body, allowing their movements. The vertebral column also provides protection for the spinal cord, which is located within the spinal canal that is formed by a central hole in each vertebra.
Normally, there are 32 to 34 vertebrae (singular: vertebra) forming the human spine. There are 24 free vertebrae and 8 to 10 fused vertebrae.
The vertebral column has the following parts:
- cervical part - consists of 7 cervical vertebrae (C1 - C7);
- thoracic part - consists of 12 thoracic vertebrae (T1 - T12);
- lumbar part - consists of 5 lumbar vertebrae (L1 - L5);
- sacral part - consists of 5 sacral vertebrae fused together, forming a single bone - the sacrum;
- coccygeal part - consists of 3 to 5 fused coccygeal vertebrae, forming a single bone - the coccyx (tailbone).
The adult human vertebral column does not form a straight line, but it has four curves along its way corresponding to parts of the spine (cervical, thoracic, lumbar and sacral). The cervical and lumbar parts of the vertebral column are curved anteriorly, while the thoracic and sacral parts curve posteriorly. The curves increase stability, flexibility of the vertebral column and its ability to absorb shock.
Disorders affecting the curvatures of the vertebral column are classed as spinal disease (dorsopathy) and include kyphosis - an excessive posterior curve in the thoracic region, lordosis - an excessive anterior curve in the lumbar region, and scoliosis - an abnormal lateral curvature, accompanied by twisting of the vertebral column.