Spinal Regions, side view
The spinal cord is a column of nerve cells and bundles of nerve fibers
which connects the brain to all parts of the body. The spinal cord itself
does not descend the entire length of the spinal canal. It ends at about
the level of the second lumbar vertebra. Below this level, the remaining
spinal nerves descend as a group of nerves resembling a horses mane, hence
their name the "cauda equina". The spinal cord gives off spinal
nerves in pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
The spinal cord and nerves are surrounded by a sac called the
dura
mater which contains them in a bath of spinal fluid. Outside the dura,
between it and the bony and ligamentous walls of the spinal canal, is the
epidural
space. It is in this space that
epidural
injections are given, including cortisone (steroid) injections to treat
spinal disorders or novocaine for regional anesthesia for surgery
or to deliver a baby.
