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As stated in the short paper On Being an Authority, I have
no intention of being a person who presents the data and then
says no other data exist or that no one should look and discover
for themselves what is real (real for this purpose is defined
as actually observed as occurring in the physical universe
by you and everyone else).
In discussion of various mechanisms, I seemed to have missed
a basic underlying datum held/put forth by quite a few doctors.
The proposed datum that is not true but
presupposed to be true is:
That a vertebra cannot slip anterior due to the
resistance of disc fibers and other tissues.
The reasons that is not true are evident on physical observations.
First, is that the disc fibers do not prevent motion in any
direction. They are slack enough to permit some free and unresisted
motion as demonstrated by Breig and others. This can also
be tested, and has been, on fluoroscopy and sequential x-rays
of people in motion studies. Those fibers and tissues do resist
extremes of motion but for them to resist motion totally in
any direction would mean no movement in that direction. (I
know this seems an obvious point disproving the assertions
that these tissues resist these motions totally but that statement
is there to be seen in quite a few doctors' comments and several
books on spinal biomechanics.) When any doc or other person
can do simple physical experiments to disprove what some researcher/scientist
has said to be true one must question the validity of the
work or the researcher and the publication printing such work.
(See the article, On Doing Research, What Most Researchers
Have Missed)
What is true is that ligaments
prevent a bone from moving very far out of place unless they
are badly stretched such as in a dislocation. BUT, this does
not mean that they hold bones in an optimal position for
mechanical leverage. This is seen in many examples and
Milkmaid's Arm is one of those.
The difficulty is that what many researchers
in the field of structural healing say is true is not based on
physical experiments but
is the result of their thought. Their calculations are based on what
someone (often someone else who just made it up) thinks with no physical experiment behind it. (Engineers
building things know better than to depend upon that line
of action in building things. They always make models to find
out if they "thought" the right way and if they
accounted for all the factors in the designing of the thing
they are building be it a building, bridge, car or even a
small toy.)
Next is the point that if the discs were to be said to be
resisting these motions so anterior slippage would not be
possible, we would not have anterolistheses/spondylolistheses
visible on plain film x-ray, with or without lysis of the
pedicles. For that matter we would not have retrolistheses/posteriolistheses
visible on plain film x-ray either.
Actual observation of physical experiments
and clinical x-rays as noted above demonstrate vertebrae
can and do move in any direction (anterior included) with a twist or without a
twist and with flexion/extension or lateral flexion/extension
or without.
An additional but possibly not noted point can be added to
the previously noted explanations:
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The spinal column and individual
vertebrae are loaded axially (top to bottom) by gravity.
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The tension of the meninges/CNS
being stretched from head to tail also pulls the ends of the
spine together.
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There are also muscles on the
posterior aspect of the spinal column which pull
inferior-superior (accounting for the axial loading in nonupright
positions).
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There are addition factors
to consider in the pulling inferior-superior on the column
such as the anterior and posterior longitudinal ligaments and the anterior
body musculature.
Any vertebra slipping in laterally outside the vertical alignment
of the column has that axial compressive force (which has
been documented by many) will be forced to remain out of position
in the direction of displacement. See illustration:
To the left you have the arrows
indicating the force of the meninges pulling the spine inward
just like a stretched rubber band. To the right you have the
effects of that force on a misaligned spine.
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If this level displaces to the right you get |
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Yes, the vertebrae on the inside of
the curve do compress. Practitioners tend to forget that
vertebrae are not of set shape and solid, they are
compressible to a great extent. That is what accounts for the
changes in compression seen when you take sitting films and
then standing films. The forces have changed and the shape of
the vertebrae are changed a bit as well.
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Attempting to correct by forcing the vertebra left
can only be done if the force of the axial compression
indicated by the large vertical arrows is exactly aligned
— which it will not be unless the vertebrae above and
below the misaligned one are exactly held in place by some
outside force.
Since that force will not exactly align as you attempt to
force the displaced vertebra left laterally, the force
will usually displace some other vertebra BUT IN A
DIFFERENT PLANE. Pushing it forward, backward or in some
type of twist.
That is why mirror image forces to correct vertebral and
spinal alignment have not worked on any sort of consistent
basis in the thousands of years it has been attempted by
various groups.
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The force pushes
the vertebra further out of position as it squeezes the ends
of the spinal column together.
To visualize this see above and
imagine a stack of blocks with rubber bushings between the
blocks that are attached at to the end of the blocks it is
between.
Pardon the crude graphics. You may need to widen your viewer
to the max width to see this as it should be viewed.
That discusses lateral
displacement. Now let us look at anterior-posterior
displacement.
If you consider that there are muscles on the posterior aspect
of the spinal column pulling inferior-superior and there are
no similar muscles on the anterior aspect (though there is
the anterior longitudinal ligament to provide some inferior-superior
pull) the axial compression forces the vertebra already displaced
anterior further anterior or lateral as in the figure to the
right below.
Both these illustrations are
thumbnails. Double click on the illustration and a full size
will pop-up in another window.
The illustration to the left is
what practitioners think of when they think of a vertebra
stuck anterior but that is not how it works. The spine above
the anterior does not stay stable in place. Since the column
above the point of the anterior is dependant upon the support
of the vertebra below, the entire column from that point up is
stuck forward. The illustration to the right is the more
accurate.
| People tend to think the
spine looks like the illustration left above or to the
right here, when a vertebra goes forward. That gives them
the impression the muscles from the vertebra above
and below can contract and that will pull posterior
(in the directions of the long arrows) pulling posterior
(short arrow) and returning the vertebra to its proper
position. It is absolutely incorrect.
See below. |
 
Anterior |
| Again, the vertebra
above are dependant upon support from the ones below.
Therefore, when a given vertebra goes forward the ones
above follow and cannot act as a stable base from which
other muscles can pull. |
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| What can, and most often does
happen, is illustrated here. The muscles pulling from one
vertebra to another contract. This rotates the vertebrae
into extension. That tilts the
vertebrae posterior and leans the entire body backward.
This is how a spinal column gets flat spots in what is
supposed to be a smooth curve from the lateral view. |
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This indicates that just at the
bottom of a flat spot is a vertebra stuck anterior (and not
posterior as Gonstead claimed).
  
         
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