Biodynamic and Biomechanical cranial approaches compared
Same action, different interpretation of effect
An example of something unconnected to cranial work may help in
understanding how identical (apparently) actions in cranial manipulation
might be interpreted quite differently.
A Western trained manual therapist or practitioner, when compressing tense,
tight soft tissues, using thumb pressure for example, might be aware that a
number of predictable, and easily explained simultaneous effects are taking
Digital pressure obviously produces mechanical stretching of connective
tissue, influencing the viscoelastic (sol/gel) properties of tissue (Barnes
1997), it also stimulates mechanoreceptors, so influencing pain perception
(Ward 1997, Melzack & Wall 1988), and of course it will temporarily
produce increased ischemia, so that on release of the pressure a flushing of
fresh oxygenated blood occurs (Travell, Simons & Travell 1999). Applied
pressure also triggers the release of pain relieving endorphins and
enkephalins (Baldry 1993).
A simple biomechanical action can therefore be seen to produce obvious
mechanical stretching effects alongside neurological, circulatory and
Now the very same pressure, applied by someone trained in the Eastern
traditions of Ayurveda or Traditional Chinese Medicine (Shia tsu), might be
conceptualised as altering the flow of prana or chi – with an energy related
outcome on health. Which practitioner is correct? Possibly both.
In cranial work it is also possible to see that performing the same activity,
say for example 4th ventricular compression, might be having a predictable
biomechanical influence by causing a degree of slack in the reciprocal
tension membranes that attach to the inner aspect of the skull, potentially
influencing venous sinus drainage.
Or, if a practitioner’s understanding of the cranial approach is biodynamic,
rather than biomechanical, this same cranial hold might be conceived to be
having a transmutational, fluid driven effect, on the healing processes of the
Some remarkable images, are to be found in a chapter of Cranial
manipulation Theory and Practice by John McPartland DO (2nd edition, due
for publication late in 2005). These illustrate some basic concepts of biodynamic cranial theory, and suggest that the embryo is a biodynamic archetype, serving as a blueprint for the body’s ability to heal itself, so that
the formative, resorbative, and regenerative fluid forces that organize
embryological development may also be present throughout life.
Biodynamic cranial practitioners postulate that external forces generate a
spatial orientation in the embryo. This becomes expressed in the material
plane by fluid forces, perhaps by electro-magnetic water hydrogen bonds
generating a matrix that governs the embryo’s development.
The tensile fluid forces required for this process were demonstrated by
Schwenk in 1996, who used micropipettes to inject streams of fluids into
water. Boundary surfaces arising between the moving fluid and the still
water vortexed into organic forms.
By changing the fluid density, or the injection speed, different forms were
created. In some experiments, the tensile quality of the fluid matrix produced
shapes that closely resemble the migratory path of neural crest cells in the
In other experiments the spatial orientations of fluid-in-a-fluid suggested
central nervous system formation in the embryo, complete with dura and pia,
cerebral hemispheres, and a corpus callosum connected to the hemispheres.
These concepts will be more fully explained and explored in the book
Biodynamic cranial practitioners correlate these concepts with Sutherland’s
description of the Tide acting as a fluid within a fluid, expressing a tensile
quality, with the ability to direct force.
More recently the reaction of genes to hydrostatic pressure during
embryogenesis has been termed “the morphogenetic mechanism” (Van
Van der Wal (1997) likened genes to the clay that forms a piece of pottery.
Clay by itself cannot form into shape, it requires the hands of the artist. And
the hands of the artist cannot act without the mind of the artist. From a
Biodynamic perspective, clay represents the genes, the hands represents the
fluid forces, and the artist’s/therapists mind represents the expression of
The therapist/practitioner working with the biodynamic model will be
attempting to influence these fluid forces, possibly by means of a process of
Biomechanical cranial therapy
Biomechanical cranial approaches regard the structures and functions of the
cranial mechanism in a quite different way, with focus more toward
evaluating structural relationships and their functional influences, including
venous and lymphatic drainage, the rhythmic cranial pulsations, and
dysfunction involving sutural articulations and fascial status, as well as the
muscular attachments to the cranium, and the relationship between the
cranium and the cervical spine.
A model that both groups accept
In recent years both schools of cranial therapy have shown particular interest
in autonomic function, as represented by the Traube-Hering-Meyer
These oscillations occur between 6 and 10 times per minute and are
variously associated with BPº, heart rate, cardiac contractility, pulmonary
blood flow, cerebral blood flow, movement of cerebrospinal fluid, and
peripheral blood, including venous volume and body thermal regulation.
Nelson et al (2002) relate Traube-Hering-Meyer wave frequencies to
palpatory cranial rhythmic impulse findings.
They have published recordings of the specific effect on the Traube-HeringMeyer oscillations of 10 to 15 minutes of cranial treatment, showing Laser Doppler blood flow velocity records before and after cranial treatment in
two healthy asymptomatic individuals. The records represent +_ 3 minutes
of continuous, unedited recording, made within 20 minutes of each other and
demonstrate the effect on autonomic balance of the treatment.
Individual no. 1 was a 55-year-old male who receved attention to craniocervical junction and cranial treatment, ±10 minutes.
Individual no. 2 was a 25-year-old female, in whom equilibration of the
cranio-cervical juncture and cranial base was achieved in ±15 minutes of
The high frequency waveform observed in all four recordings shows the
blood velocity variation with cardiac systole and diastole (THM). A
prominent, lower frequency oscillation, absent in both pre-treatment records
but seen to be prominently present in both post-treatment records, is the TH
It is quite possible that cranial treatment, even when it is focussing on
biomechanical structures, may be having a direct influence on these rhythms,
and so on both autonomic balance and the subtle fluid dynamics suggested
by Biodynamic theory. The choice of any treatment approach depends on accurate assessment
findings and the interpretations given to these, and on the belief system and
training of the practitioner.
There are probably no right and wrong choices when considering these two
models of cranial treatment – merely different ways of achieving similar
outcomes. And there is no reason why both Biodynamic and Biomechanical
approaches should not both be available to the skilled practitioner/therapist.
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