The
cord in humans may be likened to a coaxial cable, about one inch in
diameter, and is a continuation of the brain.
It looks like firm, white
fat; nerves extend out from the cord to the muscles, skin and bones, to
control movement, receive sensations and regulate bodily excretions and
secretions.
The 31 pairs of spinal nerves divide the cord into the
following segments: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1
coccygeal.