OF THE LUMBAR SPINE
What carries the
majority of your body’s
What is the role of the intervertebral discs?
What is the intervertebral disc nucleus?
What is the role of the spinal canal?
What is the role of the spinal nerve roots?
The Spinal Column and the Vertebrae
Your spinal column consists of 24 separate bones,
called vertebrae, plus the five fused bones of
the sacrum and the four fused bones of the coccyx
(often referred to as the "tail bone").
The vertebrae are stacked one on top of another
and can be divided into:
- the cervical (neck) spine: the top seven vertebrae,
thoracic (chest) spine: the middle 12 vertebrae,
- the lumbar (lower back) spine: the bottom
Support for the Vertebral (Spinal) Column
Attached to the vertebrae are muscles, tendons
and a group of strong bands, called ligaments,
together, they support the spinal column and help
to protect its delicate nerves.
The Role of the Vertebral (Spinal) Column
What Carries the Majority of Your Body's Weight?
Your spinal column enables you to walk upright.
It is the central support for your upper body and
carries the weight of your head, chest and arms.
The vertebrae in the lumbar (or lower back) portion
of your spine carry the majority of this weight.
The constant pressure from this weight, even when
you are simply sitting in a chair, is what usually
leads to problems associated with the lower back.
The Role of the Intervertebral Discs
The bony vertebrae of your spinal column are separated
from one another by "pads" of tough cartilage,
called intervertebral disk.
These discs act like "shock absorbers" during
activity, allowing the spine to move freely. How
a disc "ruptures" (bulges outward) is
shown in the drawing in Figure 2 and will be discussed
in detail on the following pages.
The Intervertebral Disc Nucleus
The center of each intervertebral disc is made
up of a gelatin-like substance (the nucleus), surrounded
by a fiber-like outer lining (the annulus).
As your body ages, the disc’s nucleus begins
to stiffen. This reduces flexibility and increases
the chances that a disc may "rupture," especially
in the lumbar spine which carries so much of your
The Spinal Canal
The spinal cord, which begins at the base of the
brain and runs within the spinal canal, ends in
the lumbar spine area in a bundle of nerves known
as the cauda equina (Figs. 3 & 4). The spinal
canal runs through the center of the spinal column
and protects the spinal cord and other delicate
The Spinal Nerve Roots
At each vertebral level, a pair of nerves branch
off from the spinal cord or the cauda equina (one
to the left and one to the right). These spinal
nerve roots are part of the body’s "electrical" system,
carrying "current" (for sensation and
movement) to specific parts of the body.
The nerve roots are protected by an "insulated" covering
in the same way a "live" electrical line
is coated to prevent direct contact with the bare
wire. A nerve root damaged by a ruptured disc may
have all or part of its "insulation" rubbed
off at the point of injury. Prior to surgery there
is no way of telling how much has been rubbed off
or how much damage has been done to the nerve (the
body’s "live electrical wire").
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