Between each vertebra is
a soft, gel-like cushion, called an intervertebral
disc. These flat, round "cushions" act like
shock absorbers by helping absorb pressure.
The discs prevent the bones from rubbing against
each other.
Each disc has a strong outer ring of fibers
called the annulus, and a soft, jelly-like
center called the nucleus pulposus. The annulus
is the strongest area of the disc. It helps
keep the disc's center intact. The annulus
is actually a strong ligament that connects
each vertebra together.
The mushy nucleus of the disc serves as the
main shock absorber. The nucleus is made up
of tissue that is very moist because it has
high water content. The water content is what
helps the disc act like a shock absorber-somewhat
like a waterbed mattress.
