The Vertebral Column
Henry Gray (1821–1865). Anatomy of the Human Body. 1918.
3.The Vertebral Column
(Columna Vertebralis; Spinal Column).
The vertebral column is a flexuous and flexible column, formed of a series of bones called vertebrae The vertebrae are thirty-three in number, and are grouped under the names cervical, thoracic, lumbar, sacral and coccygeal according to the regions they occupy; there are seven in the cervical region, twelve in the thoracic, five in the lumbar, five in the sacral, and four in the coccygeal.
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. The number of cervical vertebrae is, however, very rarely increased or diminished.
The vertebrae in the upper three regions of the column remain distinct throughout life, and are known as true or movable vertebrae; those of the sacral and coccygeal regions, on the other hand, are termed false or fixed vertebrae, because they are united with one another in the adult to form two bones—five forming the upper bone or sacrum and four the terminal bone or coccyx
With the exception of the first and second cervical, the true or movable vertebrae present certain common characteristics which are best studied by examining one from the middle of the thoracic region.
The vertebral column surrounds the spinal cord which travels within the spinal canal, formed from a central hole within each vertebra. The spinal cord is part of the central nervous system that supplies nerves and receives information from the peripheral nervous system within the body. The spinal cord consists of grey and white matter and a central cavity, the central canal. Adjacent to each vertebra emerge spinal nerves. The spinal nerves provide sympathetic nervous supply to the body, with nerves emerging forming the sympathetic trunk and the splanchnic nerves.
The spinal canal follows the different curves of the column; it is large and triangular in those parts of the column that enjoy the greatest freedom of movement, such as the cervical and lumbar regions, and is small and rounded in the thoracic region, where motion is more limited.
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