Littlejohn Tensegrity
Treatise: Considerations of Littlejohn spinal mechanics from
a tensegrity perspective.
Tensegrity structures
consist of a dichotomy of opposing components: For one, there are relatively
isolated elements, which are deemed more ‘compressive’ in nature. Secondly, one
finds a continuous net-like tension component linking and functionally
integrating these ‘islets of compression’. The author would argue that these
peculiar elements can certainly be made up of compressive or tensile physical
materials, but that they may also consist of force vectors acting in a
compressive or tensile manner. Collectively, this compression-tension system is
characterised by a unified mechanical response to external or internal
perturbations of force. The features resulting from a tensegrity-like make-up
are deemed advantageous for biomechanical modelling and can indeed be recognised
in numerous biological contexts, such as protein structures, individual cells,
bone tissue, the mammalian lung, and, allegedly, articulatory complexes such as
the knee or the shoulder. All of these are energy-efficient and light,
remarkably resilient and they respond as a functional unit to force
perturbations.
Attempts to apply tensegrity
principles to macroscopic anatomy have been few in number and were, on occasion,
criticised for being too simplistic or anatomically incorrect. Interestingly,
most such attempts were made as part of manual therapy-related research,
indicating that the model may potentially link in with fundamental concepts of
bodywork, even though so far rarely discussed in this context. It is certainly
possible to recognise certain principles and features of tensegrity within the
human body. Especially a consideration of the myofascia as the tensile
component of a whole-body tensegrity appears sensible due to its analogous
features of network-like tension and its unifying and integrating role in the
body. How anatomically inclusive such an approach can be (e.g. what the role of
the viscera may be, or how turgor can be appreciated) and how constructive it
is to manual therapy practice, remains elusive.
The author would argue that
in order to make the idea of bio-tensegrity (the application of tensegrity
principles to the human body) practical, it may necessitate integration with
existing biomechanical and philosophical models of manual therapy in general
and osteopathy in particular. In a recent qualitative study (DHS, 2014), a
participant argued that ‘Littlejohn may
indeed be the epitaph of the tensegrity model’, prompting the author to
inquire further into this matter. Ultimately, appreciation of tensegrity ideas
should facilitate conceptualisation of function and dysfunction, enable the
practitioner in his/her physical assessment to link palpatory experience to a
scientific model and osteopathic concepts, and, eventually, prompt the choice
of techniques.
Revisiting the spinal
mechanics postulated by J.M. Littlejohn, the functional view taken in his spinal
conceptualisation is striking. Segregation of spinal curves was made according
to function as dictated by vertebral body or facet joint shape, rather than
mere anatomical detail. In summary, the O/A complex functions as a unit, the
cervical function is extended distally to T4, typical dorsal areas are confined
to about T5-T10 whilst T12 already constitutes a firm lumbar vertebra. Then
again, the L/S junction works as a unit. Within such an evaluation, the
‘pivotal’ role of C5, T9 and L5 was emphasised and they were highlighted to be
prone to biomechanical dysfunction because of local force alterations. Another
fundamental concept of Littlejohn was the introduction of triangles relating to
the direction of force passing distally from the head through the spine.
Essentially, the spinal curves were complemented by a polygon of gravitational
forces passing through and alongside the spine. Here, T4 and L3 were considered
the main weight-bearing points and T9 the keystone of a compressive dorsal
curve.
At first glance, this spinal
assessment has very little to do with a compression-tension system as described
above. Moreover, in Littlejohn’s writings there are ‘pivots’, ‘levers’ and
gravity-dependent force vectors. Advocates of a ‘biotensegrity’ make every
attempt to ban these ‘traditional’ biomechanical terms from there analysis,
stating that in a true tensegrity such levers could not exist, but that only
non-linear force distribution along tensile trains could integrate focal
compression points. However, this vocabulary was, at the time of J.M.
Littlejohn, the only one disposable. The concept of a keystone is another one
counterintuitive to tensegrity, and Littlejohn saw the T9 vertebra to be the
keystone of a mainly compressive dorsal curvature; Cervical and lumbar curves
were deemed more ‘fluid’ in nature and bar of a keystone. Nowadays, no serious
biomechanical researcher would hold that the spine is a column of blocks,
disregarding tension and lateral force transmission – such a notion has become
the ‘bad guy’ or antagonist for many advocates of biotensegrity necessary to
highlight the ‘uniqueness’ of their own approach. This discussion aside,
neither J.M. Littlejohn regarded the spine as a compressive column; Far from
it. On closer examination, Littlejohn was no less concerned with the soft
tissue influences on the spine than he was with joint shape and curve function.
For example, posterior and anterior cervical muscles were thought to influence
the way C2 and C5 would move, respectively (one being drawn posteriorly by the
suboccipital musculature and the other tending to flex forward under the
tension of the scalene and longus colli musculature). The gravity lines
constituting the polygon of forces, have also been termed anterior and
posterior ‘lines of articular tension’ (Campbell, undated), indicating that
rather than a fixed compressive force, the body adapts along these lines to
balance gravity. More importantly, the spine is not conceptualised as a column,
instead emphasis is made of particular points within a functional unit. These
points, either functional pivots or centres of gravity, could, alternatively,
be conceptualised as areas of compression. They are isolated but linked
functionally by the influence of tension. This tension can be conveyed through
myofascial structures, thus, at least on a conceptual level, linkable to
tensegrity.
More importantly,
Littlejohn’s spinal model is adaptive. This, however, requires a little more
abstraction from the original texts. The lumbar spine was said to act as a
‘block’ under the influence of the thoracolumbar fascia. This is, however, only
the case when the current demand is that of stability and it demands increasing
activity of the lumbar erector spinae, abdominal musculature, psoas,
diaphragmatic crurae etc. This increase in tension will then unify lumbar
segements and allow them to function compressively. The spine can still be seen
to function as a tensegrity, just the compressive element has grown. In the
absence of such tension more segmentalised function is possible.
The cervical spine possesses a greater degree of freedom, according to
its general function of mobility. Functional units are smaller and segmental
control better. Within its limits, a similar increase of pre-stress in the
myofascial network can nonetheless provide more stability when required.
Littlejohn’s spinal mechanics are thus not contradictory to the notion of
tensegrity at all – as long as they are perceived from a functional point of
view. Anatomical structures may be morphologically more or less capable to
function under either compression or tension, but their roles may shift. Units
of compression and units of tension may change depending on the momentary
demand.
What is notably missing in
Littlejohn’s teachings is the consideration of the spine in space. The emphasis
on gravity as a pre-determined direction of force becomes misleading once the
position of the spine in space is altered. Standing on the head, L3 is unlikely
to still be the main centre of gravity. By saying that Littlejohn’s concept is
adaptive, the author means that none of the segmental specifications is
necessarily fixed. L3 is not always the centre of gravity and the T/L may
sometimes have to function as a real transition area even though the anatomy
makes T9/10 more apt for such a task. Rather, Littlejohn’s specifications have
to be seen as guidelines for a comparably normal and static spine. In
three-dimensional motion these points will inevitably have to shift. What
remains constant are the points of soft tissue attachment and the general
anatomy. Also, spinal biomechanics need to be integrated with the function of
the limbs. Here, again, anatomical evaluation of myofascial force transmission
can guide the practitioner. In certain movements, tension is relayed along
predetermined myofascial lines and planes, which can be more or less adaptable
to stress. Determining how functional such force transmission is, will,
eventually, be the clinical challenge. Considerations of symmetry and scale,
and primarily matching of palpatory perception with individual experience of
functional and dysfunctional tension patterns are at the heart of such an
evaluation. The role of the spine as the integratory centre of any body
movement has since its conception been a fundamental tenet of osteopathy.
Littlejohn’s emphasis on spinal
mechanics can thus be explained: if the spine is functional, all other
movements will be integrated effectively. A similar notion integrates spinal
biomechanics with visceral function, both via autonomic reflexes and connective
tissue connections.
Today, as our understanding
of neurophysiology and the importance of connective tissue has increased
dramatically, a consideration of traditional spinal models may seem out of
place. Certainly, the author would argue, Littlejohn’s view of the spine has on
occasion been adhered to overly dogmatically and is, moreover, likely to be
incorrect in some ways. The general notion, however, that some areas of the
spine are more adaptive to compressive forces than others and that a
triangulated network of (myofascial) tension balances these points, is more
modern than ever and was, back then, certainly way ahead of the time. With this
fundamental notion of Littlejohn in mind, viewing the spine as a tensegrity
becomes a much more practical approach, since Littlejohn developed a general
guide for which areas and tissues should ideally act in a particular way –
compressive or tensile. Within such an approach, there is still plenty of scope
for individual treatment experience and the integration of more modern concepts
relating to myofascia and neuromuscular control. The author would argue that
knowledge of the tensegrity model also facilitates conceptualisation of
Littlejohn’s triangles and pivot/gravity points. Of course, in reality these
triangles are much more complex and could even be broken down to individual
joint complexes of focal compression and global tension (see next treatise: A
consideration of Sutherland’s balanced ligamentous tension from a tensegrity
perspective). In motion and during a manual (palpatory) assessment, these
complex triangles shift under the practitioners hands and may evoke mental
images relating to a tensegrity. With experience and based on clinical models
such as Littlejohn’s, this will allow the osteopath to make a functional
evaluation of the structure as represented by its anatomical relationships and
the forces between them. Dysfunction thus identified will have to be balanced
by releasing inappropriate tension at the appropriate point. The choice of
technique is then - very A.T. Still - a secondary consideration.
(Campbell, undated, p. 54:
‘The body is not a rigid structure and although it has to obey mechanical laws,
its main property is adaptation through muscular and ligamentous tension, fluid
and air pressure and distribution of blood.’)
consist of a dichotomy of opposing components: For one, there are relatively
isolated elements, which are deemed more ‘compressive’ in nature. Secondly, one
finds a continuous net-like tension component linking and functionally
integrating these ‘islets of compression’. The author would argue that these
peculiar elements can certainly be made up of compressive or tensile physical
materials, but that they may also consist of force vectors acting in a
compressive or tensile manner. Collectively, this compression-tension system is
characterised by a unified mechanical response to external or internal
perturbations of force. The features resulting from a tensegrity-like make-up
are deemed advantageous for biomechanical modelling and can indeed be recognised
in numerous biological contexts, such as protein structures, individual cells,
bone tissue, the mammalian lung, and, allegedly, articulatory complexes such as
the knee or the shoulder. All of these are energy-efficient and light,
remarkably resilient and they respond as a functional unit to force
perturbations.
Attempts to apply tensegrity
principles to macroscopic anatomy have been few in number and were, on occasion,
criticised for being too simplistic or anatomically incorrect. Interestingly,
most such attempts were made as part of manual therapy-related research,
indicating that the model may potentially link in with fundamental concepts of
bodywork, even though so far rarely discussed in this context. It is certainly
possible to recognise certain principles and features of tensegrity within the
human body. Especially a consideration of the myofascia as the tensile
component of a whole-body tensegrity appears sensible due to its analogous
features of network-like tension and its unifying and integrating role in the
body. How anatomically inclusive such an approach can be (e.g. what the role of
the viscera may be, or how turgor can be appreciated) and how constructive it
is to manual therapy practice, remains elusive.
The author would argue that
in order to make the idea of bio-tensegrity (the application of tensegrity
principles to the human body) practical, it may necessitate integration with
existing biomechanical and philosophical models of manual therapy in general
and osteopathy in particular. In a recent qualitative study (DHS, 2014), a
participant argued that ‘Littlejohn may
indeed be the epitaph of the tensegrity model’, prompting the author to
inquire further into this matter. Ultimately, appreciation of tensegrity ideas
should facilitate conceptualisation of function and dysfunction, enable the
practitioner in his/her physical assessment to link palpatory experience to a
scientific model and osteopathic concepts, and, eventually, prompt the choice
of techniques.
Revisiting the spinal
mechanics postulated by J.M. Littlejohn, the functional view taken in his spinal
conceptualisation is striking. Segregation of spinal curves was made according
to function as dictated by vertebral body or facet joint shape, rather than
mere anatomical detail. In summary, the O/A complex functions as a unit, the
cervical function is extended distally to T4, typical dorsal areas are confined
to about T5-T10 whilst T12 already constitutes a firm lumbar vertebra. Then
again, the L/S junction works as a unit. Within such an evaluation, the
‘pivotal’ role of C5, T9 and L5 was emphasised and they were highlighted to be
prone to biomechanical dysfunction because of local force alterations. Another
fundamental concept of Littlejohn was the introduction of triangles relating to
the direction of force passing distally from the head through the spine.
Essentially, the spinal curves were complemented by a polygon of gravitational
forces passing through and alongside the spine. Here, T4 and L3 were considered
the main weight-bearing points and T9 the keystone of a compressive dorsal
curve.
At first glance, this spinal
assessment has very little to do with a compression-tension system as described
above. Moreover, in Littlejohn’s writings there are ‘pivots’, ‘levers’ and
gravity-dependent force vectors. Advocates of a ‘biotensegrity’ make every
attempt to ban these ‘traditional’ biomechanical terms from there analysis,
stating that in a true tensegrity such levers could not exist, but that only
non-linear force distribution along tensile trains could integrate focal
compression points. However, this vocabulary was, at the time of J.M.
Littlejohn, the only one disposable. The concept of a keystone is another one
counterintuitive to tensegrity, and Littlejohn saw the T9 vertebra to be the
keystone of a mainly compressive dorsal curvature; Cervical and lumbar curves
were deemed more ‘fluid’ in nature and bar of a keystone. Nowadays, no serious
biomechanical researcher would hold that the spine is a column of blocks,
disregarding tension and lateral force transmission – such a notion has become
the ‘bad guy’ or antagonist for many advocates of biotensegrity necessary to
highlight the ‘uniqueness’ of their own approach. This discussion aside,
neither J.M. Littlejohn regarded the spine as a compressive column; Far from
it. On closer examination, Littlejohn was no less concerned with the soft
tissue influences on the spine than he was with joint shape and curve function.
For example, posterior and anterior cervical muscles were thought to influence
the way C2 and C5 would move, respectively (one being drawn posteriorly by the
suboccipital musculature and the other tending to flex forward under the
tension of the scalene and longus colli musculature). The gravity lines
constituting the polygon of forces, have also been termed anterior and
posterior ‘lines of articular tension’ (Campbell, undated), indicating that
rather than a fixed compressive force, the body adapts along these lines to
balance gravity. More importantly, the spine is not conceptualised as a column,
instead emphasis is made of particular points within a functional unit. These
points, either functional pivots or centres of gravity, could, alternatively,
be conceptualised as areas of compression. They are isolated but linked
functionally by the influence of tension. This tension can be conveyed through
myofascial structures, thus, at least on a conceptual level, linkable to
tensegrity.
More importantly,
Littlejohn’s spinal model is adaptive. This, however, requires a little more
abstraction from the original texts. The lumbar spine was said to act as a
‘block’ under the influence of the thoracolumbar fascia. This is, however, only
the case when the current demand is that of stability and it demands increasing
activity of the lumbar erector spinae, abdominal musculature, psoas,
diaphragmatic crurae etc. This increase in tension will then unify lumbar
segements and allow them to function compressively. The spine can still be seen
to function as a tensegrity, just the compressive element has grown. In the
absence of such tension more segmentalised function is possible.
The cervical spine possesses a greater degree of freedom, according to
its general function of mobility. Functional units are smaller and segmental
control better. Within its limits, a similar increase of pre-stress in the
myofascial network can nonetheless provide more stability when required.
Littlejohn’s spinal mechanics are thus not contradictory to the notion of
tensegrity at all – as long as they are perceived from a functional point of
view. Anatomical structures may be morphologically more or less capable to
function under either compression or tension, but their roles may shift. Units
of compression and units of tension may change depending on the momentary
demand.
What is notably missing in
Littlejohn’s teachings is the consideration of the spine in space. The emphasis
on gravity as a pre-determined direction of force becomes misleading once the
position of the spine in space is altered. Standing on the head, L3 is unlikely
to still be the main centre of gravity. By saying that Littlejohn’s concept is
adaptive, the author means that none of the segmental specifications is
necessarily fixed. L3 is not always the centre of gravity and the T/L may
sometimes have to function as a real transition area even though the anatomy
makes T9/10 more apt for such a task. Rather, Littlejohn’s specifications have
to be seen as guidelines for a comparably normal and static spine. In
three-dimensional motion these points will inevitably have to shift. What
remains constant are the points of soft tissue attachment and the general
anatomy. Also, spinal biomechanics need to be integrated with the function of
the limbs. Here, again, anatomical evaluation of myofascial force transmission
can guide the practitioner. In certain movements, tension is relayed along
predetermined myofascial lines and planes, which can be more or less adaptable
to stress. Determining how functional such force transmission is, will,
eventually, be the clinical challenge. Considerations of symmetry and scale,
and primarily matching of palpatory perception with individual experience of
functional and dysfunctional tension patterns are at the heart of such an
evaluation. The role of the spine as the integratory centre of any body
movement has since its conception been a fundamental tenet of osteopathy.
Littlejohn’s emphasis on spinal
mechanics can thus be explained: if the spine is functional, all other
movements will be integrated effectively. A similar notion integrates spinal
biomechanics with visceral function, both via autonomic reflexes and connective
tissue connections.
Today, as our understanding
of neurophysiology and the importance of connective tissue has increased
dramatically, a consideration of traditional spinal models may seem out of
place. Certainly, the author would argue, Littlejohn’s view of the spine has on
occasion been adhered to overly dogmatically and is, moreover, likely to be
incorrect in some ways. The general notion, however, that some areas of the
spine are more adaptive to compressive forces than others and that a
triangulated network of (myofascial) tension balances these points, is more
modern than ever and was, back then, certainly way ahead of the time. With this
fundamental notion of Littlejohn in mind, viewing the spine as a tensegrity
becomes a much more practical approach, since Littlejohn developed a general
guide for which areas and tissues should ideally act in a particular way –
compressive or tensile. Within such an approach, there is still plenty of scope
for individual treatment experience and the integration of more modern concepts
relating to myofascia and neuromuscular control. The author would argue that
knowledge of the tensegrity model also facilitates conceptualisation of
Littlejohn’s triangles and pivot/gravity points. Of course, in reality these
triangles are much more complex and could even be broken down to individual
joint complexes of focal compression and global tension (see next treatise: A
consideration of Sutherland’s balanced ligamentous tension from a tensegrity
perspective). In motion and during a manual (palpatory) assessment, these
complex triangles shift under the practitioners hands and may evoke mental
images relating to a tensegrity. With experience and based on clinical models
such as Littlejohn’s, this will allow the osteopath to make a functional
evaluation of the structure as represented by its anatomical relationships and
the forces between them. Dysfunction thus identified will have to be balanced
by releasing inappropriate tension at the appropriate point. The choice of
technique is then - very A.T. Still - a secondary consideration.
(Campbell, undated, p. 54:
‘The body is not a rigid structure and although it has to obey mechanical laws,
its main property is adaptation through muscular and ligamentous tension, fluid
and air pressure and distribution of blood.’)
