spinal column

spinal column, bony column forming the main structural support of the skeleton of humans and other vertebrates, also known as the vertebral column or backbone. It consists of segments known as vertebrae linked by intervertebral disks and held together by ligaments. In human beings, the spinal column of the child contains more vertebrae than the adult, in whom a number become fused into two immovable bones, the sacrum and the coccyx, forming the back of the pelvis. The 24 movable vertebrae are the 7 cervical (neck), 12 thoracic (back of chest), and 5 lumbar (loin). The remaining vertebrae include 5 fused sacral, and between 3 and 5 fused caudal. Each vertebra has a somewhat cylindrical bony body (centrum), a number of winglike projections, and a bony arch. The bodies of the vertebrae form the strong but pliable supporting column of the skeleton. The arches are positioned so that the space they enclose is in effect a tube, the vertebral canal. It houses and protects the spinal cord, and within it the spinal fluid circulates. Ligaments and muscles are attached to various projections of the vertebrae. The 12 pairs of ribs that make up the front of the chest are linked to the thoracic vertebrae. The spine is subject to abnormal curvature, injury, infections, tumor formation, arthritic disorders, and puncture or slippage of the cartilage disks. Scoliosis is one relatively common disease which affects the spinal column. It involves moderate to severe lateral curvature of the spine, and, if not treated, may lead to serious deformities later in life.

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vertebral column

 or spinal column or spine or backbone

Flexible column extending the length of the torso. In humans, it consists of 32–34 vertebrae, with different shapes and functions in each of five regions: 7 cervical, in the neck (including the atlas and axis, modified for free movement of the skull); 12 thoracic, in the chest; 5 lumbar, in the lower back; 5 sacral (fused into the sacrum, part of the pelvic girdle); and 3 to 5 coccygeal (vestigial tailbones fused into the coccyx). The body of each vertebra is separated from its neighbours by cushioning intervertebral disks of cartilage. Behind the body is a Y-shaped vertebral (neural) arch with structures extending up and down to form joints with the adjacent vertebrae and to the back and sides to provide attachment points for muscles and ligaments. The spine supports the torso and protects the spinal cord.

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spinal column

a series of contiguous or interconnecting bony or cartilaginous segments that surround and protect the spinal cord

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spinal column [′spīn·əl ‚käl·əm]

(anatomy)

spine