The term "spine" or "backbone"
refers to the bony structures and soft tissues of the vertebral column.
The vertebrae are the bony segments surrounding and protecting the soft
tissue of the spinal cord and nerve roots serving different regions of
the body. Technically, the spine consists of 33 vertebrae, although some
of the structures of the lower back and tailbone are fused together.
In addition to its function
in structural support of the body, the vertebral column also serves as
the housing for the spinal cord. The spinal cord sends signals to
and from the brain along the millions of nerves and nerve pathways. Motor
nerves carry impulses from the brain to the body, controlling movement.
Sensory nerves travel from the body to the brain where the brain interprets
the sensation, such as heat, cold, and pressure. The vertebral canal, which
houses the spinal cord, is formed by the alignment of openings at the center
of each vertebra. Ligaments and muscles of the back hold the vertebral
column in place, and discs provide cushioning between each vertebra.
The discs are composed of
two components, the tough, fibrous outer shell and a soft, jelly-like inner
core. The discs function as shock absorbers, allowing the back to move
freely within its normal range of motion and reducing the forces against
the vertebral bones and nerves. The nerve root is the segment of the nerve
that exits the spinal column. |
 |
Specific structures of the
vertebral column are referenced according to anatomic regions. For example,
there are seven cervical or neck vertebrae. The very first or top cervical
vertebra supports the skull and is called the atlas. Just beneath the cervical
vertebrae are the 12 vertebrae of the thoracic, or chest, region. The next
lower region is called the lumbar, or lower back region, which contains
five vertebrae. The sacral, or buttocks, region contains five vertebrae,
which are fused into one vertebral structure. Similarly, the vertebrae
of the coccygeal region are fused into a single structure, the tailbone.
|
