Fascial plasticity – a newneurobiological explanation:
Part 1. . . . . . . . . . . . .
Robert Schleip
In myofascial manipulation an immediate tissue release is often felt under the working
hand. This amazing feature has traditionally been attributed to mechanical properties
of the connective tissue. Yet studies have shown that either much stronger forces or
longer durations would be required for a permanent viscoelastic deformation of fascia.
Fascia nevertheless is densely innervated by mechanoreceptors which are responsive to
manual pressure. Stimulation of these sensory receptors has been shown to lead to a
lowering of sympathetic tonus as well as a change in local tissue viscosity. Additionally
smooth muscle cells have been discovered in fascia, which seem to be involved in active
fascial contractility. Fascia and the autonomic nervous system appear to be intimately
connected. A change in attitude in myofascial practitioners from a mechanical
perspective toward an inclusion of the self-regulatory dynamics of the nervous system
is suggested. r 2003 Elsevier Science Ltd. All rights reserved.
Introduction
Fascia – what a fascinating tissue!Also known as dense irregularconnective tissue, this tissuesurrounds and connects everymuscle, even the tiniest myofibril,and every single organ of the body.It forms a true continuity
throughout our whole body. Fasciahas been shown to be an importantelement in our posture andmovement organization. It is oftenreferred to as our organ of form
(Varela & Frenk 1987, Garfin et al.1981).
Many approaches to manualtherapy focus their treatment on thefascia. They claim to alter either thedensity, tonus, viscosity or
arrangement of fascia throughthe application of manual pressure(Barnes 1990, Cantu & Grodin1992, Chaitow 1980, Paoletti 1998,Rolf 1977, Ward 1993). Theirtheoretical explanations usuallyrefer to the ability of fascia toadapt to physical stress. How thepractitioner understands the natureof this particular responsivenessof fascia will of course influencethe treatment. Unfortunately,fascia is often referred to in termsof its mechanical properties alone.This series of articles will notonly explore the neural dynamicsbehind fascial plasticity, butwill also offer new perspectivesfor myofascial treatmentmethods.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Journal of Bodywork and Movement Therapies (2003)
7(1),11^19r 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S1360-8592(02)00067-0
S1360-8592/03/$ - see front matter
Robert Schleip MA
Rolfing Faculty, European Rolfing Association
e.V., Kapuzinerstr. 2S, D-80337, Munich, Germany
Correspondence to: Robert Schleip
E-mail: [email protected]
Website: www.somatics.de
Received April 2002
Revised May 2002
Accepted June 2002
F A S C I A L P H Y S I O L O G Y
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The classical gel-to-solmodel
Many of the current training schoolswhich focus on myofascial treatmenthave been profoundly influenced byRolf (1977). In her own work Rolfapplied considerable manual orelbow pressure to fascial sheets inorder to change their density andarrangement. Rolf’s ownexplanation was that connectivetissue is a colloidal substance inwhich the ground substance can beinfluenced by the application ofenergy (heat or mechanicalpressure) to change its aggregateform from a more dense ‘gel’ state toa more fluid ‘sol’ state. Typicalexamples of this are common gelatinor butter, which get softer byheating or mechanical pressure.This gel-to-sol transformation,also called thixotropy (Juhan 1987),has been positively confirmed tooccur as a result of long-termmechanical stress applications toconnective tissue (Twomey andTaylor 1982).
But the question arises: is thismodel also useful to explain theimmediate short-term plasticity offascia? In other words, what actuallyhappens when a myofascialpractitioner claims to feel a ‘tissue
release’ under the working hand? Inmost systems of myofascialmanipulation, the duration of anindividual ‘stroke’ or technique on aparticular spot of tissue is between afew seconds and 1 1
2minute. Rarely is
a practitioner seen – or is it taught –to apply uninterrupted manualpressure for more than 2minutes.Yet often the practitioners reportfeeling a palpable tissue releasewithin a particular ‘stroke’. Suchrapid – i.e. below 2minutes – tissuetransformation appears to be moredifficult to explain with thethixotropy model. As will be shownlater, studies on the subject of ‘time
and force dependency’ of connectivetissue plasticity (in terms of creep
and stress relaxation) have shownthat either much longer amounts oftime or significantly more force arerequired for permanent deformationof dense connective tissues (Currier& Nelson 1992).
Additionally the problem ofreversibility arises: in colloidalsubstances the thixotropic effectlasts only as long as the pressure orheat is applied. Within minutes thesubstance returns to its original gelstate – just think of the butter in thekitchen. This is definitely not anattractive implication of this modelfor the practitioner.
Piezoelectricity ^ or thebody as a liquid crystal
Oshman and others have addedpiezoelectricity as an intriguingexplanation for fascial plasticity(Oshman 2000, Athenstaedt 1974).Piezo (i.e. pressure) electricity existsin crystals in which the electriccenters of neutrality on the inside ofthe crystal lattice are temporarilyseparated via mechanical pressurefrom the outside and a small electriccharge can be detected on thesurface. Since connective tissue canbe seen to behave like a ‘liquidcrystal’ (Juhan 1987), these authorspropose that the cells which produceand digest collagen fibers (calledfibroblasts and fibroclasts) might beresponsive to such electric charges.To put it simply: pressure from theoutside creates a higher electriccharge, which then stimulates thefibroblasts to increase theirproduction rate of collagen fibersin that area. Additionally thefibroclasts might have a selectivebehavior not to ‘eat’ fibers which areelectrically charged. In a nutshell:more stress, more charge, morefibers. Similar processes havealready been shown to exist in boneformation after fractures as well asin wound healing.
Nevertheless, the processesinvolved seem to require time as an
important factor. The half-life spanof non-traumatized collagen hasbeen shown to be 300–500 days, andthe half-life of ground substance1.7–7 days (Cantu & Grodin 1992).While it is definitely conceivable thatthe production of both materialscould be influenced bypiezoelectricity, both life cyclesappear too slow to account forimmediate tissue changes that aresignificant enough to be palpated bythe working practitioner.
The traditionalexplanations areinsu⁄cient
Both models, thixotropy andpiezoelectricity, are appealingconcepts to explain long-term tissuechanges. Yet it seems, additionalmodels are needed when it comes toshort-term plasticity. Laboratorystudies on the subject of time andforce dependency of connectivetissue plasticity (in vitro as well as invivo) have shown the followingresults: in order to achieve apermanent elongation of collagenfibers one needs to apply either anextremely forceful stretch of 3–8percent fiber elongation, which willresult in tissue tearing along withinflammation and other side effectswhich are usually seen asundesirable in a myofascial session.E.g. for an 18mm distal iliotibialband such permanent elongationhappens at 60 kg and more(Threlkeld 1992). Or it takes morethan an hour (which can be taken atseveral intervals) with softer 1–1.5percent fiber elongation, if onewants to achieve permanentdeformation without tearing andinflammation (Currier & Nelson1992, Threlkeld 1992).
For short-term application ofstress the typical relationships areshown in Fig. 1. Microfailure is seenas the breaking of some individualcollagen fibers and of some fiberbundles which results in a
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permanent (plastic) elongation ofthe tissue structure. This is followedby a cycle of tissue inflammationand repair. Based on measurementswith different kinds of paraspinaltissues, Threlkeld calculates thatmicrofailure occurs at around 224–1.136N which equals 24–115 kg(Threlkeld 1992). While high-velocity thrust techniques mightcreate forces within that range, itseems clear that the slower softtissue manipulation techniques arehardly strong enough to create thedescribed tissue response.
This research leads to a simplethought experiment. In everyday lifethe body is often exposed to pressuresimilar to the application of manualpressure in a myofascial treatmentsession. While the body naturallyadapts structurally to long-termfurniture use, it is impossible toconceive that adaptations couldoccur so rapidly that any unevenload distribution in sitting (e.g.while reading this article) wouldpermanently alter the shape of yourpelvis within a minute. It seemsessential therefore that we find
additional models – besides thethixotropic and piezoelectricconcepts – to account for thepalpable tissue changes that occur ina treatment session.
The need for a more rapidself-regulatory system
From an evolutionary perspective itmakes sense that animals have aslowly adapting plasticity system inorder to adjust to patterns of long-term use. In addition to this capacitythey have also developed a morerapid system of adapting their formand local tissue density to temporarydemands. This regulation system isopen for adaptation to how theanimal perceives its interaction withthe environment. It seems logicalthat this ability of being morerapidly adaptable is mediated by –or at least connected to – a bodysystem which is involved in theperception of our needs as well as ofthe environment. Traditionally, thisbody system has been called thenervous system.
It is therefore suggested that theself-regulatory qualities of the
client’s nervous system must beincluded in an explanatory model ofthe dynamics of fascial plasticity inmyofascial manipulations. Theauthor’s own experiments in treatinganesthetized people (with verysimilar results to that noted whenmanually treating very fresh piecesof animal meat) have shown thatwithout a proper neural connection,the tissue does not respond as it doesunder normal circumstances(Schleip 1989).
Although it has not beenconsidered very much in recenttimes, the inclusion of the nervoussystem in attempting to understandfascial responsiveness is not a newconcept altogether, since thefounder of osteopathy AndrewTaylor Still wrote more than acentury ago.
The soul of man with all the streams of
pure living water seems to dwell in the
fascia of his body. When you deal with
the fascia, you deal and do business
with the branch offices of the brain,
and under the general corporation law,
the same as the brain itself, and why
not treat it with the same degree of
respect? (Still 1899).
The nervous system asa wet tropical jungle
Many people think of the nervoussystem as an old-fashionedtelephone switchboard system of theindustrial age and thereforeincapable of representing finer andmore complex processes such as ‘lifeenergy’, etc. The reader is cordiallyinvited to consider this to be anoutdated model. Current concepts inneurobiology see the brain more as aprimarily liquid system in which fluiddynamics of a multitude of liquidand even gaseous neurotransmittershave come to the forefront.Transmission of impulses in ournervous system often happens viamessenger substances that travelalong neural pathways as well asthrough the blood, lymph,
Fig. 1 Stress–strain curve of dense connective tissue. Most forces generated during daily life load
the tissue in the linear region of the curve and produce non-permanent elongation. Microfailure
with permanent elongation happens at extreme loads only and is accompanied by tearing and
inflammation. The region of overlap of the microfailure zone with the physiologic loading zone
varies with the density and composition of the tissue, yet for most fascial tissues it would be well
above a 20 kg loading (drawing based on Threlkeld 1992). Figure by Twyla Weixl, Munich,
Germany.
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cerebrospinal fluid or groundsubstance (Kandel 1995). Thisglobal system for rapid bodyregulations is inseparably connectedwith the endocrinal and immunesystem. Rather than picturing thenervous system as a hard-wiredelectric cable system (which in theview of many bodyworkers is thenof course incapable of beinginvolved in more subtle energeticphenomena) picture it in yourmind’s eye as a wet tropical jungle
(Schleip 2000). This jungle is a self-regulatory field with an amazingamount of complexity, continualreorganization and plasticity, evenin adults.
The Golgi re£ex arc asa breakthrough
Unfortunately, the precise details ofthe neural dynamics of fascia haverarely been explored. Cottingham(1985) presented a milestoneproposal when he suggested aneurophysiological concept whichwas readily adopted by otherauthors (Ward 1993, Schleip 1989)and which will be briefly describedhere: Golgi receptors are said to befound all over in dense properconnective tissues. They exist inligaments (here called Golgi end
organs), in joint capsules, as well asaround myotendinous junctions(here called Golgi tendon organs).These sensory receptors arearranged in series with fascial fibersand respond to slow stretch byinfluencing the alpha motor neuronsvia the spinal cord to lower theirfiring rate, i.e. to soften relatedmuscle fibers. Cottingham suggestedthat during soft tissue manipulation– as well as in Hatha yoga posturesand slow active stretching – theseGolgi receptors are stimulated,which results in a lower firing rate ofspecific Alpha motor neurons, whichthen translates into a tonus decreaseof the related tissues.
Too bad ^ it is not a simplere£ex!
Unfortunately, later research hasshown that passive stretching of amyofascial tissue does not stimulatethe Golgi tendon organs (Jami1992). Such a stimulation happensonly when the muscle fibers areactively contracting. The reason forthis lies in the arrangement of theGolgi tendon receptors. They arearranged in series with the musclefibers. When the muscle with itsrelated myofascia is passivelyelongated, most of the stretch will betaken up or ‘swallowed’ by aresulting elastic elongation of themuscle fibers. This is of coursedifferent in active clientcontractions, in which the Golgitendon organs function to providefeedback information aboutdynamic force changes during thecontraction (Lederman 1997).
But there are other Golgireceptors
Does this mean that deep tissuework (in which the client often ispassive) will not involve the Golgireflex loop? Perhaps, but notnecessarily. These measurementshave been done with passive jointextension movements, and not yetwith the application of direct tissuepressure as in a myofascialmanipulation.
Furthermore, it is important tonote that only less than 10% of theGolgi receptors are found whollywithin tendon. The remaining 90%are located in the muscular portionsof myotendinous junctions, in theattachment transitions ofaponeuroses, in capsules, as well asin ligaments of peripheral joints(Burke and Gandeva 1990).
Studies of the fine antigravityregulation in bipedal stance havealso revealed a new functional rolefor Golgi receptors. In order tohandle the extreme antigravity
balancing challenges as a biped, ourcentral nervous system can reset theGolgi tendon receptors and relatedreflex arcs so that they function asvery delicate antigravity receptors(Dietz et al. 1992). This explains thatsome of the leg’s balancing reactionsin standing occur much quicker thanit would take for a nerve impulsefrom the brain to the leg. In otherwords, the previously discussed andwell-documented role of the Golgiorgans (as a feedback mechanismabout dynamic force changes duringactive contractions) covers only aminor functional role of theseorgans. For example, little is knownabout the sensitivity and relatedreflex function of those Golgireceptors that are located inligaments (Chaitow 1980) or in jointcapsules. It seems possible – yet alsoquite speculative – to assume thatthese less-explored Golgi receptorscould indeed be stimulated withsome stronger deep tissue techniques(Table 1).
And there are Ru⁄ni andPacini corpuscles
A detailed histochemical study ofthe thoracolumbar fascia at theBiomedical Engineering Institute ofthe Ecole Polytechnique in Montrealrevealed that it is richly populatedby mechanoreceptors (Yahia et al.1992). The intrafascial receptorswhich they described consist of threegroups. The first group are the largePacini corpuscles plus the slightlysmaller Paciniform corpuscles. Theegg-shaped Pacini bodies respond torapid changes in pressure (yet not toconstant unchanging pressure) andto vibrations. A bit smaller are thePaciniform corpuscles, which have asimilar function and sensitivity. Asecond group are the smaller andmore longitudinal Ruffini organswhich do not adapt as quickly andtherefore respond also to long-termpressure. It seems likely that thePacinian receptors are being
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stimulated only by high-velocitythrust manipulations as well as invibratory techniques, whereas theRuffini endings will also be activatedby slow and deep ‘melting quality’soft tissue techniques.
Both types of intrafascialmechanoreceptors, the Pacinian/Paciniform and the Ruffini bodies,are found in all types of denseproper connective tissue, i.e. inmuscle fascia, tendons, ligaments,aponeuroses, and joint capsules. Inmyotendinous junctions thePacinian corpuscles are morefrequent on the tendinous site (asopposed to the Golgi tendon organswhich are more frequent on themuscular site). They have also beenshown to be more frequent in thedeeper portions of joint capsules, indeeper spinal ligaments, and in
investing (or enveloping) muscularfasciae like the antebrachial, crural,abdominal fascia or the fascia of themasseter, the lateral thigh, in plantaras well as palmar tissues, and in theperitoneum (Stilwell 1957). TheRuffini endings are specially dense intissues associated with regularstretching like the outer layer of jointcapsules, the Dura mater, the
ligaments of peripheral joints, andthe deep dorsal fascia of the hand.At the knee joint the Ruffini endingsare more frequent at anterior andposterior ligamentous and capsularstructures, whereas Pacinian bodiesare more accumulated medially andlaterally of the joint (van den Berg &Capri 1999).
It is of interest to note that Ruffiniendings are specially responsive totangential forces and lateral stretch(Kruger 1987) and that stimulationof Ruffini corpuscles is assumed toresult in a lowering of sympatheticnervous system activity (van denBerg & Capri 1999). This seems to fitto the common clinical finding thatslow deep tissue techniques tend tohave a relaxing effect on local tissuesas well as on the whole organism.
Our reference scene
Figure 3 illustrates the neural tissueplasticity dynamics at this level. Itis suggested that the followingscene should be used as a referencepoint for this article. Imagine apractitioner working slowly withthe connective tissue around thelateral ankle, in an area with no
striated muscle fibers. (Choosingthis reference scene allows us tofocus on intrafascial dynamicsonly, and – for the purpose of thisarticle – to ignore the stimulationof intramuscular mechanoreceptorsand other effects which would beinvolved in the analysis of manyother myofascial workingsituations.) If that practitionerreports a ‘tissue release’, what hashappened? Possibly the manualtouch stimulated some Ruffiniendings which then triggered thecentral nervous system to changethe tonus of some motor units inmuscle tissue which is mechanicallyconnected to the tissue under thepractitioner’s hand.
An unknown universewithin us
In order to discuss the third groupof intrafascial mechanoreceptorsdescribed by Yahia and hercolleagues in Montreal, it isnecessary to go on a short excursion.It commonly comes as a big surpriseto many people to learn that ourrichest and largest sensory organ isnot the eyes, ears, skin, or vestibular
Table1 Mechanoreceptors in fascia
Receptor type Preferred location Responsive to Known results of stimulation
Golgi
Type Ib
K Myotendinous junctions
K Attachment areas of aponeuroses
K Ligaments of peripheral joints
K Joint capsules
K Golgi tendon organ: to
muscular contraction.
K Other Golgi receptors: probably
to strong stretch only
Tonus decrease in related
striated motor fibers
Pacini and Paciniform
Type II
K Myotendinous junctions
K deep capsular layers
K spinal ligaments
K investing muscular tissues
Rapid pressure changes and vibrations Used as proprioceptive
feedback for movement control
(sense of kinesthesia)
Ruffini
Type II
K Ligaments of peripheral joints,
K Dura mater
K outer capsular layers
K and other tissues associated
with regular stretching.
K Like Pacini, yet also to sustained pressure.
K Specially responsive to
tangential forces (lateral stretch)
Inhibition of sympathetic activity
Interstitial
Type III and IV
K Most abundant receptor type.
Found almost everywhere,
even inside bones
K Highest density in periosteum.
K Rapid as well as sustained pressure
changes.
K 50% are high-threshold units, and 50%
are low-threshold units
K Changes in vasodilation
K plus apparently in plasma
extra-vasation
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system but is in fact our muscleswith their related fascia. Our centralnervous system receives its greatestamount of sensory nerves from ourmyofascial tissues. Yet the majorityof these sensory neurons are so smallthat until recently little has beenknown about them (Engeln 1994).
If one studies a typical musclenerve (e.g. the tibial nerve), itconsists of almost three times moresensory fibers than motor fibers.This points to a fascinating principlethat sensory refinement seems to bemuch more important than themotor organization. However let usnot get distracted by this. Whilemany of the nerve fibers in a typicalmotor nerve have a vasomotorfunction, which regulate blood flow,the largest group of fibers aresensory nerves. Now comes the reallyinteresting point: of these sensorynerves only a small fraction, or 20%,belong to the well-known types Iand II nerves which originate inmuscle spindles, Golgi organs,Pacini corpuscles and Ruffiniendings (see Fig. 2). The majority, orfour times as many, belong to aninteresting group of types III and IV
sensory nerves which are hardlymentioned in most textbooks(Mitchell & Schmidt 1977).
What dowe know aboutthis hidden network?
These hidden neurons are muchsmaller in diameter and are nowcommonly called interstitial muscle
receptors. A better name would beinterstitial myofascial tissue
receptors since they also existabundantly in fascia. A minority ofthese nerves are covered by a verythin myelin sheath (type III), but90% of these nerves areunmyelinated (type IV). Theseinterstitial receptors are slower thanthe types I and II nerves and most ofthem originate in free nerve endings.
In the past it was assumed thatthese nerve endings are mostly painreceptors. Some have also beenshown to be involved in thermo- orchemoception. While many of thesereceptors are multimodal, researchhas shown that the majority of theseinterstitial receptors do in factfunction as mechanoreceptors, whichmeans they respond to mechanicaltension and/or pressure (Mitchell &Schmitt 1977).
This large group of interstitialmechanoreceptors can be furtherdivided into two subgroups of equalsize: low-threshold pressure units(LTP units) and high-threshold units
(HTP). A study of the Achillestendon of cats revealed that abouthalf of types III and IV endingsencountered were LTP units andresponded to light touch, even totouch as light as ‘‘with a painter’s
brush’’ (Mitchell & Schmidt 1977).Based on this latter finding, does itnot seem possible – indeed likely –that soft tissue manipulation mightinvolve stimulation of types III andIV receptors?
Recent insights into thephysiology of pain have shown thatseveral interstitial tissue receptorsfunction both as mechanoreceptors(usually as HPT units) and as painreceptors. In the presence of pain –and the support of variousneuropeptides – their sensitivitychanges such that normalphysiological pressure changes oftenlead to strong and chronic firing ofthese receptors. This explains whycurrent research has revealed thatpain often exists without anymechanical irritation of nervousstructures as was frequentlyassumed by the root-compressionmodel (Chaitow & DeLany 2000).
What are they doing?
This of course triggers the questionabout the natural functional role ofinterstitial mechanoreceptors in thebody. What regular consequences orreactions have been associated withan excitation of this hidden and richsensory network? Of course some ofthem function as pain receptors. By1974 a Japanese study had alreadyrevealed that types III and IVreceptors in the fascia of temporalis,masseter and infrahyoid musclesshow ‘responses to the mandibular
movement and the stretching of the
fascia and the skin’, and it wastherefore suggested that these nerveendings are concerned ‘with the
sensation of position and movement of
the mandible’ (Sakada 1974).Furthermore the majority of these
types III and IV mechanoreceptors
Fig. 2 Within a typical muscle nerve there are almost three times as many sensory neurons than
motor neurons. Note that only a small portion of the sensory information comes from types I and
II afferents which originate in muscle spindles, Golgi receptors, Pacinian and Ruffini endings. The
majority of the sensory input comes from the group of types III and IV afferents or interstitial
receptors which are intimately linked with the autonomic nervous system. Figure by Twyla Weixl,
Munich, Germany.
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have been shown to have autonomic
functions, i.e. stimulation of theirsensory endings leads to a change inheart rate, blood pressure,respiration, etc. Stimulation of typeIV receptors tends to increasearterial blood pressure (Coote &Perez-Gonzales 1970) whereasstimulation of type III receptors canboth increase and decrease bloodpressure. Several studies have shownthat an increase of static pressure onmuscles tends to lower arterial bloodpressure (Mitchell & Schmitt 1977).It seems that a major function ofthis intricate network of interstitialtissue receptors is to fine tune thenervous system’s regulation of bloodflow according to local demands,and that this is done via very closeconnections with the autonomicnervous system.
Touch research with catsand humans
Based on this research it should notcome as a surprise that slow deeppressure on the soft tissue of cats hasbeen shown to lead to a reduction inmuscle tonus measured by EMGactivity (Johansson 1962) and thatslow stroking of the back in catsproduces a reduction in skintemperature as well as signs ofinhibition of the gamma motorsystem (von Euler & Soderberg1958).
Furthermore, it has been proventhat deep mechanical pressure to thehuman abdominal region (Folkow1962), as well as sustained pressureto the pelvis (Koizumi & Brooks1972), produces parasympatheticreflex responses, includingsynchronous cortical EEG patterns,increased activity in vagal fibers, anda decreased EMG activity.
According to the model ofhypothalamic tuning states by ErnstGellhorn, an increase in vagal tonedoes not only trigger changes in theautonomic nervous system andrelated inner organs, but also tends
to activate the anterior lobe of thehypothalamus. Such a ‘trophotropic
tuning’ of the hypothalamus theninduces a lower overall muscletonus, more quiet emotionalactivity, and an increase insynchronous cortical activity, bothin cats as well as in humans(Gellhorn 1967). It thereforeappears that deep manual pressure –specifically if it is slow or steady –stimulates interstitial and Ruffinimechanoreceptors, which results inan increase of vagal activity, whichthen changes not only local fluiddynamics and tissue metabolism,but also results in global musclerelaxation, as well as a morepeaceful mind and less emotionalarousal.
On the other hand, sudden deeptactile pressure or pinching or othertypes of strong and rapidmanipulations have been shown toinduce a general contraction ofskeletal muscles (Eble 1960),particularly of ‘genetic flexormuscles’ (Schleip 1993) which areinnervated via a ventral primaryramus from the spinal cord.
Talking to the belly brain
Mechanoreceptors have been foundabundantly in visceral ligaments aswell as in the Dura mater of thespinal cord and cranium. It seemsquite plausible that most of theeffects of visceral or craniosacralosteopathy could be sufficientlyexplained by a simulation ofmechanoreceptors with resultingprofound autonomic changes, andmight therefore not need to rely onmore esoteric assumptions(Arbuckle 1994).
Recent discoveries concerning therichness of the enteric nervous system
(Gershon 1999) have taught us thatour ‘belly brain’ contains more than100 million neurons and workslargely independent of the corticalbrain. It is interesting to note thatthe very small connection between
these two brains of a few thousandneurons consists of nine times asmany neurons involved in processesin which the lower brain tells theupper one what to do, comparedwith the number of neuronsinvolved in the top-down direction.Many of the sensory neurons of theenteric brain are mechanoreceptors,which – if activated – trigger amongother responses, importantneuroendocrine changes. Theseinclude a change in the productionof serotonin – an important corticalneurotransmitter 90% of which iscreated in the belly – as well as otherneuropeptides, such as histamine
(which increases inflammatoryprocesses).
What are we doing?
Myofascial manipulation involves astimulation of intrafascialmechanoreceptors. Theirstimulation leads to an alteredproprioceptive input to the centralnervous system, which then resultsin a changed tonus regulation ofmotor units associated with thistissue (Fig. 3). In the case of a slowdeep pressure, the relatedmechanoreceptors are most likelythe slowly adapting Ruffini endingsand some of the interstitialreceptors; yet other receptors mightbe involved too (e.g. spindlereceptors in affected muscle fibersnearby and possibly someintrafascial Golgi receptors).
Measurements on themechanoreceptors of the knee jointligaments have shown that theirstimulation leads to weak effects inalpha motor neurons, yet topowerful changes in gamma motorneurons. This means that theseligamentous mechanoreceptors areprobably used as proprioceptivefeedback for preparatory regulation(preprogramming) of muscle tonusaround this joint (Johansson et al.1991). For myofascial practitionersthis is fascinating news, as it suggests
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that simulation of fascialmechanoreceptors may primarilylead to changes in gamma motortone regulation. While the alpha andgamma motor system are usuallycoactivated, there are someimportant differences between them.The alpha system originatesprimarily in the cortex, and it isparticularly involved in volitionaland precise movements of theextremities, whereas the gammasystem originates in older brain stemstructures and plays a strong role inthe more global and unconsciouspostural organization of antigravity-extensor muscles and chronicmusculo-emotional attitudes(Glaser 1980, Henatsch 1976,Juhan 1987).
Nomuscle is a functionalunit
When discussing any changes inmotor organization, it is importantto realize that the central nervoussystem does not operate ‘in muscles’,i.e. a muscle is never activated as awhole. The functional units of themotor system are the so-called motor
units, of which we have severalmillion in our body, much like aschool of fish that have learned toswim together. Depending on thequality of sensory feedback, thesemillions of motor units can be
individually regulated (Basmajian &De Luca 1985). We can now applythis understanding to our referencescene, in which a practitioner isworking on the connective tissuearound the lateral ankle. When thepractitioner reports a tissue release,it may be that it is caused by alowered firing rate of only a few fish(motor units) in the vicinity, andthat this movement is transmitted tothe tissue under the practitioner’shand. If the practitioner then feelsthe change and responds in a
supportive way toward theseparticular fish, other fish may soonfollow the new direction, which ofcourse leads to additional ‘releasesensations’ for the practitioner, andso on (Fig. 4).
Conclusion
Immediate fascial plasticity cannotbe understood by mechanicalproperties alone. Fascia is denselyinnervated by mechanoreceptors.Manual stimulation of these sensoryendings probably leads to tonuschanges in motor units which aremechanically linked to the tissueunder the practitioner’s hand. Atleast some of these responses areprimarily regulated by a change ingamma motor tone, rather than inthe more volitional alpha motorsystem. Of particular interest are theRuffini organs (with their highresponsiveness to tangentialpressure) and the very rich networkof interstitial receptors, sincestimulation of both of thesereceptors can trigger profoundchanges in the autonomic nervoussystem. Part 2 of this article series
Tonus change Centralof related skeletal Nervous System
motor units
Palpable tissue Stimulation ofresponse mechanoreceptors
Tissue manipulations
Fig. 3 The ‘Central Nervous System Loop’ (inspired by Cottingham). Stimulation of
mechanoreceptors leads to a lowered tonus of skeletal motor units which are mechanically linked
with the tissue under the practitioner’s hand. The involved intrafascial mechanoreceptors are
most likely Ruffini endings, Pacinian corpuscles (with more rapid manipulations), some of the
interstitial receptors, plus possibly some intrafascial Golgi receptors.
Fig. 4 Myofascial tissue as a school of fish. A practitioner working with myofascial tissue may
feel several of the motor units responding to touch. If the practitioner then responds supportively
to their new behavior, the working hand will soon feel other fish joining, and so forth. Figure by
Twyla Weixl, Munich, Germany.
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will include the discovery andfunction of intrafascial smoothmuscle cells. It will show how fascialmechanoreceptors can triggerimmediate viscosity changes of theground substance, and howfibromyalgia might be related to allthat. Several practical applicationsfor the practitioner will be given.
REFERENCES
Arbuckle BE 1994 Selected Writings.
Indianapolis American Academy of
Osteopathy
Athenstaedt H 1974 Pyroelectric and
piezoelectric properties of vertebrates.
Annals of the New York Academy of
Sciences 238: 68–110
Barnes JF 1990 Myofascial Release: The
Search of Excellence. Rehabilitation
Services Inc., Paoli, PA, Medicine, W.B.
Saunders Co.
Basmajian JV, De Luca C 1985 Muscles Alive
– Their Functions Revealed by
Electromyography. Williams & Wilkins,
Baltimore
Burke D, Gandeva SC 1990 Peripheral motor
system, In: Paxines G (ed). The Human
Nervous System Vol. 1: Academic Press,
San Diego, p 133
Cantu RI, Grodin AJ 1992 Myofascial
Manipulation – Theory and Clinical
Application. Aspen Publication,
Gaithersburg, MD
Chaitow L 1980 Soft Tissue Manipulation.
Thorsons, Wellingborough
Chaitow L, DeLany JW 2000 Clinical
Application of Neuromuscular
Techniques, Vol. 1. Churchill
Livingstone, Edinburgh
Cottingham JT 1985 Healing through Touch
– A History and a Review of the
Physiological Evidence. Rolf Institute
Publications, Boulder, CO
Coote JH, Perez-Gonzales JF 1970 The
response of some sympathetic neurons to
volleys in various afferent nerves. Journal
of Physiology London 208: 261–278
Currier DP, Nelson RM 1992 Dynamics of
Human Biologic Tissues. F.A. Davis
Company, Philadelphia
Dietz V et al. 1992 Regulation of bipedal
stance: dependency on ‘load’ receptors.
Experimental Brain Research 89: 229–
231
Eble JN 1960 Patterns of response of the
paravertebral musculature to visceral
stimuli. American Journal of Physiology
198: 429–433
Engeln H 1994 Konzert der Muskeln und
Sinne. GEO Wissen May: 90–97
Folkow B 1962 Cardiovascular reactions
during abdominal surgery. Annals of
Surgery 156: 905–913
Garfin SR et al. 1981 Role of fascia in
maintenance of muscle tension and
pressure. Journal of Applied Physiology
51(2): 317–320
Gellhorn E 1967 Principles of Autonomic–
Somatic Integration: Physiological Basis
and Psychological and Clinical
Implications. University of Minesota
Press, Minneapolis, MN
Gershon MD 1999 The Second Brain.
Harper-Collins, New York
Glaser V 1980 Eutonie. Karl F. Haug Verlag,
Heidelberg
Henatsch H-D 1976 Bauplan der peripheren
und zentralen sensomotorischen
Kontrollen. In: Physiologie des
Menschen, Vol. 14. Urban &
Schwarzenberg Munchen
Heppelman B et al. 1995 Fine sensory
innervation of the knee joint capsule by
group III and group IV nerve fibers in the
cat. Journal of Comparative Neurology
251: 415–428
Jami L 1992 Golgi tendon organs in
mammalian skeletal muscle: functional
properties and central actions.
Physiological Reviews 73(3): 623–666
Johansson B 1962 Circulatory response to
stimulation of somatic afferents. Acta
Physiologica Scandinavica 62 (Suppl.
198): 1–92
Johansson H et al. 1991 Receptors in the knee
joint ligaments and their role in the
biomechanics of the joint. Critical
Reviews in Biomedical Engineering 18(5):
341–368
Juhan D 1987 Job’s Body. Station Hill Press,
Barrytown, NY
Kandel ER 1995 Essentials of neural science
and behavior. Appleton & Lange, New
York
Koizumi K, Brooks C 1972 The integration
of autonomic system reactions: a
discussion of autonomic reflexes, their
control and their association with
somatic reactions. Ergebnisse der
Physiologie 67: 1–68
Kruger L 1987 Cutaneous sensory system. In:
Adelman G (ed.). Encyclopedia of
Neuroscience: Vol. 1 pp 293–294
Lederman E 1997 Fundamentals of Manual
Therapy. Churchill Livingstone,
Edinburgh
Mitchell JH, Schmidt RF 1977
Cardiovascular reflex control by afferent
fibers from skeletal muscle receptors.
In: Shepherd JT et al. (eds). Handbook
of Physiology, Sect. 2, Vol. III,
Part 2. American Physiological Society
Bethesda, MA, pp 623–658
Oshman JL 2000 Energy Medicine. Churchill
Livingstone, Edinburgh
Paoletti S 1998 Les Fascias – Role des Tissues
dans la Mecanique Humaine. Le Prisme,
Vannes cedex, France
Pongratz D, Spath M 2001 Fibromyalgia.
Fortschritte der Neurologie und
Psychiatrie 69(4): 189–193
Price JM et al. 1981 Biomechanics.
Mechanical Properties of Living
Tissues. Springer Verlag, New York,
pp 371–379
Rolf IP 1977 Rolfing: The Integration of
Human Structures. Dennis Landman,
Santa Monica
Sakada S 1974 Mechanoreceptors in fascia,
periosteum and periodontal ligament.
Bulletin of the Tokyo Medical and
Dental University 21 (Suppl.): 11–13
Schleip R 1989 A new explanation of the
effect of Rolfing. Rolf Lines 15(1): 18–20
Schleip R 1993 Primary reflexes and
structural typology. Rolf Lines 21(3):
37–47
Schleip R 2000 Lichtblicke im Dschungel der
Gehirnforschung. FeldenkraisZEIT 1:
47–56
Still AT 1899 Philosophy of Osteopathy.
Academy of Osteopathy, Kirksville, MO
Stilwell D 1957 Regional variations in the
innervation of deep fasciae and
aponeuroses. The Anatomical Record
127(4): 635–653
Threlkeld AS 1992 The effects of manual
therapy on connective tissue. Physical
Therapy 72(12): 893–901
Twomey L, Taylor J 1982 Flexion, creep,
dysfunction and hysteresis in the
lumbar vertebral column. Spine 7(2):
116–122
van den Berg F, Cabri J 1999 Angewandte
Physiologie – Das Bindegewebe des
Bewegungsapparates verstehen und
beeinflussen. Georg Thieme Verlag,
Stuttgart, Germany
Varela FJ, Frenk S 1987 The organ of form:
towards a theory of biological shape.
Journal of Social Biology and Structure
10: 73–83
von Euler C, Soderberg V 1958 Co-ordinated
changes in temperature thresholds for
thermoregulatory reflexes. Acta
Physiologica Scandinavica 42: 112–129
Ward RC 1993 Myofascial release concepts.
In: Basmajian V, Nyberg R (eds).
Rational Manual Therapies. Williams &
Wilkins, Baltimore, MD
Yahia L et al. 1992 Sensory innervation of
human thoracolumbar fascia. Acta
Orthopaedica Scandinavica 63(2):
195–197
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