2. What is a spinal disc?
The disc is a
tough, gristly shock
absorber that sits in
between the bones
of the spine.
It separates the
bones, lets them
move and supports
them.
3. What does a Normal Disc look
like?
A normal disc has two
different parts
A tough outer area
called the annulus
fibrosis
A slightly softer inner
area called the
nucleus pulposis
4. A Normal Disc from the Top
If you look at a disc
from the top down
it looks a little bit
like a tree stump.
Rings of tough
outer fibres encircle
the softer inner
centre.
5. How Does the Disc Work
When weight goes
through the disc
the pressure
inside increases -
this improves the
discs strength
and stiffness.
The pressure
inside spreads the
load evenly
across all the
surfaces.
6. What is a Disc Bulge?
A disc bulge occurs
when the tough, outer
layer becomes slightly
weaker. This allows the
centre to shift away from
the middle.
This shift causes the
outer area to bulge -
usually backward and
sideways.
7. Disc Bulge from the Side
When a disc bulges it
sometimes squashes
or irritates a nerve root.
The most commonly
irritated nerve roots are
the ones that make up
the sciatic nerve.
This is why disc bulges
are one of the most
common causes of
sciatica.
Sciatica = irritation of
the sciatic nerve.
8. What is a Disc Herniation or
Prolapse?
A prolapse or
herniation is more
severe than a bulge.
It is caused by the
outer area weakening
enough to allow the
inner, softer annulus to
escape out of the disc.
A prolapse can also
irritate or squash a
nerve.
9. What is a Slipped Disc?
A slipped disc is a
myth.
Discs can’t slip as
they are firmly
attached to the
bones above and
below.
When people talk
about a slipped disc
they are talking
about either a bulge
or a prolapse.
