The
back is a complicated arrangement of bones,
ligaments, muscles, tendons and nerves.
— In some ways it is amazingly strong, yet it can
easily be damaged.
 Many of us don't take the precautions that are
necessary to protect our backs from injury.
— Which is why more than 80% of both on and off
the job injuries involve the back or neck.
 But back problems are not inevitable.
— You can prevent back injuries, if you
understand how the back "works.
 When we say that someone has a lot of
"backbone" we mean that they are "upstanding" and
solid.
— Yet our backs are also amazingly flexible.
— The "foundation" of your back, the spine, is
rigid enough to support more than half of your
body weight.
— But the spine also has enough flexibility for
you to bend down and touch your toes.
2  To accomplish these "dual functions" the
spine
is made up of 33 individual bones known as
"vertebrae," twenty four of which are moveable.
They are: — The seven "cervical" (neck) vertebrae...
which
support your skull and allow you to move your
head.
— The twelve thoracic (middle back) vertebrae...
which hold your rib cage in place.
— The five vertebrae in the "lumbar" region of
your back... which enable you to bend at the waist.
 These vertebrae are "hinged" with "facet
joints" that guide their movement and provide
stability.
 The vertebrae are cushioned from one another by
"intervertebral discs."
— These "shock absorbers" consist of a soft,
gelatinous nucleus surrounded by a tough, elastic
outer casing.
Because the lumbar and cervical regions of the
spine are so flexible, these areas are
particularly vulnerable to injury.
— In fact most people will end up hurting the
lumbar region of their backs at some point in
their lives.
— The resulting pain can be anything from a
persistent dull ache... to a sudden, sharp stabbing
or stinging sensation.
 Strained muscles and sprained ligaments are the
most common causes of back pain.
— With proper treatment these injuries usually
heal within a few weeks.
— Back pain like this that lasts less than three
months is considered to be an "acute" condition.
 When back pain persists or frequently reoccurs,
it is considered to be "chronic."
— Chronic back pain may indicate that something
is wrong with the spine itself.
 "Ruptured" or "herniated" discs are the most
common type of spinal injury.
— Although sometimes referred to as a "slipped"
disk, intervertebral discs don't really pop out
from between the vertebrae.
— What actually happens is that the outer,
elastic part of the disk ruptures, and the
gelatinous nucleus protrudes into the spinal
canal... putting pressure on the spinal cord.
— This causes severe back pain... and since the
spinal cord is directly involved, there is often
numbness or pain in other parts of the body as
well.
 Most disc ruptures occur to the lower two discs
in the lumbar region.
— This is because they are subjected to more
"heavy lifting" than any other discs in the
spine.
4  However, herniated discs can also occur
in the
cervical region.
Often, these injures are due to
"whiplash."
— Whiplash is caused by any sudden jolt, such as
a car accident, that violently throws the head
backwards.
 Properly treated, herniated discs usually heal
by themselves, without the need for surgery.
— But it can take several years for a disc to
fully heal.