CHAPTER 4
LUMBAR SLIPPED DISC
(ALSO CALLED HERIATED OR PROLAPSED DISC)
What is it?
The spine consists of a series of vertebrae that are stacked on top of one
another from the neck to the pelvis. These vertebrae are connected and kept
in the correct position by the discs that are between the vertebrae and also the
facet joints that are located on the side of the vertebral bodies, which inter-
lock with one another. There are also supporting ligaments and tendons. The
discs between the two adjacent vertebrae are composed of a central, soft,
jelly-like substance, called the nucleus pulposus, and an outer, tougher
fibrous part, called the annulus fibrosus. In some cases the tough annulus
fibrosus becomes damaged and tears, leaving a defect in the strong outer
layer. A bit of the nucleus pulposus can then push through this tear and end
up in the spinal canal and press against the nerves in the spinal canal (see fig-
ure 4.1). This can be caused by a traumatic injury, but is usually due to an
inborn predisposition towards weak discs.
The spinal cord extends from the brainstem to the lower spine and ends just
below the level of the thoracic and lumbar spine junction. A slipped lumbar
disc simply compresses nerve roots that are dangling in the spinal canal. This
is because there is no spinal cord at this level, but only nerve roots that orig-
inate from the spinal cord.
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