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Fascia: a morphological description and classification system based on a literature review.


Fascia is an uninterrupted viscoelastic tissue which forms a functional 3-dimensional collagen matrix. (1-3) It surrounds and penetrates all structures of the body extending from head to toe, thus making it difficult to isolate and develop its nomenclature. (1) The Federative International Committee on Anatomical Terminology (FICAT), in the 1998 edition of Terminologia Anatomica, points out significant flaws in the nomenclature system for fascia, largely stemming from the anglocentric nature of the terms used, and lack of formal international applicability. (4) The usage of the terms superficial fascia and deep fascia is considered incorrect by the FICAT because histological terminology referring to layers of the connective tissue varies too much internationally to be generalized by these two terms. (4) Common names of certain fascia are also considered to be inaccurate, e.g., Scarpa's, Camper's, and Colles'. It is suggested that they be replaced with subcutaneous tissue of abdomen membranous layer, subcutaneous tissue of abdomen fatty layer and membranous layer of perineum, respectively. (4) Terminologia Anatomica gives a long list of terms related to their definition of fascia, and attempts to offer a system for grouping various fasciae based on embryological origins and modes of development. However, clear details on the groupings and justification for this strategy are not given, and it remains difficult to organize and properly use the multiple fascial terms. Furthermore, the application of these terms for communication in research, education, and clinical practice remains difficult and impractical. In light of the contribution made by the FICAT on fascial terminology, it is important to utilize their work on terminology and suggest how it may be further arranged and used in practice. Indeed, a number of experts have called for further development on the description and nomenclature of all fasciae and have made significant contributions of their own. (5-7)

Recent advances in research within the fields of biomechanics, gross anatomy, and histology, provide the international research community with an opportunity to improve the terminology associated with fascia, thereby improving intra- and inter-professional communications. (5), 8-10 However, discrepancies still exist concerning the official definition, terminology, classification and clinical significance of fascia. (5-6)

For example, the FICAT broadly defines fascia as sheaths, sheets or other dissectible connective tissue aggregations. The First International Fascia Research Congress (2007) formulated a comprehensive definition of fascia as the soft tissue component of the connective tissue system, emphasizing its uninterrupted, three-dimensional web-like extensions and highlighting its functional attributes. (1,4) The Congress went on to include joint and organ capsules, muscular septa, ligaments, retinacula, aponeuroses, tendons, myofascia, neurofascia and other fibrous collagenous tissues as forms of fascia, inseparable from surrounding connective tissues. (1) The broad nature of these two definitions is controversial, and not all of the tissues have been widely accepted into common usage. Thus, a consistent terminology to classify and categorize fascia has not been formally established and accepted internationally. (5-6) Gray's textbook approach to naming fascia regionally based on the adjacent or overlaying structures is a practical approach, however, this suggests fascia has a beginning and an end, which is not true to its form. (11-12) Thus, the topographical approach is important when identifying regional fascia, but it is not used consistently in practice internationally, nor does it help to describe the functional role of the regional fascia.

A more recent ontology highlights the importance of two functional forms of fascia, connecting and disconnecting, for which fiber orientation and descriptions of fascia's role in proprioception are key justifications for each category. (7) In support of this principle, there is an extensive body of work demonstrating that significant amounts of force are transmitted amongst multiple antagonist and synergistic muscle groups across joint capsules through various sections of extra- and intramuscular fascia. (7-8,13-15)

Although the recent ontologies grounded in fascial function represent an advance in classification, the complexities of fascia make it necessary to expand on these two categories (connecting and disconnecting) to further sort and describe all groups of fascia according to their attributes reported recently in the literature. (7) These additional attributes include: collagen type ratio, extracellular matrix proteins, nerve fiber types, myofascial force transmitting potential, details on fiber orientation, and influence on the circulatory system. (8,16-21)

Lack of consistent terminology has a negative effect on communication within health professions, and impedes collaborations in research. (22) Since fascia represents a topic of growing interest worldwide, it should be a priority to reduce ambiguity in fundamental terms so that this field of research can properly advance. For example, the lack of common definitions and nomenclature hinders communication between those involved in the process of diagnosis and treatment of pelvic pathologies in everyday practice. (23) One study revealed this by comparing the unofficial/common terms being used in the field and the terms provided by the Terminologia Anatomica, demonstrating how this text can be used to improve consistency in the nomenclature. While we do accept the validity of a topographical approach in naming fascia, it does not take into account the fact that fascia doesn't have a beginning and end like muscle, nor does a topographical approach account for fascia's microscopic features, or diversity of its functional characteristics. (5-7,12)


The aim of the present study is to develop a classification system for fascial structures, based primarily on their functional properties, but also incorporating morphologic al characteristics identified in the literature, and utilizing internationally accepted terminology from the FICAT. (4,24)


A review of the literature on fascia was conducted with electronic searches of EBSCO databases, PubMed, and Google Scholar, along with hand searches of proceedings from the past two International Fascia Research Congresses (2007, 2009). Search strategies in EBSCO and PubMed consisted of individual and combined MeSH term searches for "Fascia" and "Connective Tissue" using specific limiters for our topic to emphasize anatomy. These search terms were also paired separately with various keywords--"terminology", "extracellular matrix", "collagen", and "function". Results were limited to English, full text peer reviewed journal articles, conference proceedings, and textbooks. Inclusion was limited to articles with abstracts related to morphology, terminology, and/or clinical aspects of fascia. Information was then used to help organize fascia terminology, utilizing terms from two texts: Terminologia Anatomica and Terminologia Histologica. (4,24)


In section A below, we present the results of our literature review, discussing the anatomical, histological, and biomechanical features of fascia, and its innervation. Then in section B, we outline our resulting proposal for a new classification system (Table 1) incorporating these features of fascia. It is important to first understand the key characteristics and the divergent classifications of fascia at gross anatomical, histological, and biomechanical perspectives before outlining the details of these four categories.

A. Literature Review

I. Overview

The range of research advances revealed in the literature includes observations on imaging, advanced dissection and staining techniques, as well as modeling of tissue deformation, and in vitro cellular processes. (10,12,25-30) Areas of interest at the past two (2009, 2010) Fascia Research Congresses have included: biomechanics, innervation, vascularisation, molecular structure, clinical relevance, and terminology. (31) Upon review of the advances in fascia research, we see that fascia is not a passive structure, but a functional organ of stability and motion, virtually inseparable from all surrounding tissue.

II. Gross Anatomy

Gross anatomical studies of fascia demonstrate an array of characteristics based on location, density, fiber direction, and fascia's relationship to surrounding structures. (19,26-27) Based on location, the FICAT describes the following fasciae: i) in relation to the body regions: fascia of head and neck, fascia of trunk, and fascia of limbs, ii) in relation to the surrounding structures: subcutaneous fascia, fascia of muscles, visceral fascia, parietal fascia, and fascia extraserosalis which represents any other fascia which lies inside the parietal fascia and outside the visceral fascia. (4)

Fascia's key characteristic, continuity, helps explain concepts such as myofascial force transmission. (3) Hunjing describes biomechanical features of extramuscular and intramuscular force transmission in rat specimens where surrounding connective tissues are seen to influence force potential and connect muscle groups. (13-15) Dissectional observations of the intramuscular connective tissue (IMCT) show this fascia to influence length of sarcomeres to improve force production. (15) Other morphological descriptions of fascia characterize it as being optimally designed to take up tensional forces in the musculoskeletal system.

In the past, classical dissection techniques have essentially ignored fascia, simply removing it to get to muscle and deeper structures. (5) Subsequently, it was revealed through careful dissection that fascia commonly occurs as an undulating layered system of different connective tissue types. (19,28-29) Three-dimensional models of the crural and thoracolumbar fasciae demonstrate that the "deep fasciae" are formed of three sub-layers of connective tissue with different densities and orientations. (19,29) It was discovered that in each sub-layer the collagen fibers are parallel to each other, whereas the orientation between the fibers of adjacent layers changes, forming an angle of approximately 70-80 degrees with each other. (29) This allows denser fascial sheets to slide freely over underlying layers, without significant friction, and enhances fascia's ability to take up strain in virtually all directions. (29)

It is difficult to gain an appreciation for the true appearance of fascia, aside from basic structure, in embalmed cadavers. Direct observation of fascia's appearance and behavior in a living, hydrated body, has been conducted with recent fluoroscopic imaging under the skin of the dorsal forearm, shedding new light on how this sliding collagenous system works. (32-33) These observations demonstrate that fascia incorporates a water dense vacuolar system able to slide independent of the rate of contraction in muscle around it and able to conduct structures like capillaries throughout sections of myofascia. (32-33) The viscoelastic nature of fascia can only be observed in hydrated tissue, and in embalmed tissue we are only observing an artifact of the living tissue. A better appreciation for the true gross appearance of fascia can be gained through fresh body dissections, and in vivo via direct imaging techniques. (34)

Pathological changes in fascia have been observed with special imaging techniques, such as ultrasonic elastography that displays deformation and the elasticity of soft tissues. (34) This technology allows a non-invasive estimation of tissues stiffness based on the fact that soft tissue has greater tissue displacement than hard tissue when externally compressed. (10) By further quantifying the properties of the soft tissues, as with recent 3-D mathematical models of fascial deformation, insight will be gained into the effects of manual treatments beneath the skin and how the body responds to various forces. (30,35-36)

III. Histology

Fascia has specific cells, ground substance, and fiber types that make it a form of connective tissue proper. (16,37-38) A better understanding of fascia at the cellular level gives insight into its functional properties. (39) Clear changes to the extracellular matrix (ECM) in the form of adhesive sites between microscopic filaments have been studied in "scarred" fascia. (40-41) Collagen types have also been shown to vary with mechanical forces and strains. (39) We hypothesize that the functional properties of fascia are reliant on the composition of the ECM, specific cells, and filaments, including but not limited to the ratio of collagen types.

Collagen, a triple helix glycoprotein, is the key structural fiber that gives connective tissue its ability to resist tension. (17,37-38) There are twenty five distinct collagen types recognized in the Ross histology textbook and atlas, and twenty eight collagen types recognized in the latest review by Gordon. (16,37) Although, type I collagen is the main type accounting for 90% of the human body's collagen, fascia contains an array of collagen type combinations in cluding, but not limited to, types I, III, IV, V, VI, XI, XII, XIV, XXI. (16-17,37-38) Collagen provides resistance to tension and stretch, which commonly occur in fascial tissues, such as ligaments, tendons, sheaths, muscular fascia and deeper fascial sub-layers. (37)

Collagen type III, also known as reticular fiber, is involved in forming the scaffolding for the cells of the loose connective tissues related to the endoneurium, vascular walls, and smooth muscle. (1-2,17) A collagen fibril needs the support of not only fibrillar collagen types, but also a mix of non-fibrillar forms known as fibril-associated collagens with interrupted triple helices (FACITs). (16) The functions of FACITs include: i) anchoring to the basement membrane, ii) regulating the diameter of fibrils, iii) forming lattice networks, and iv) acting as transmembrane structures. (16) These fibrils are important to the integrity and function of fascia within the ECM. Elastic fibers within the ground substance give fascia its characteristic stretch. (29,37-38,42)

A combination of multiple types of collagen within the extracellular matrix forms a unique structure, like a blueprint that reflects the function and compliance of fascia in various regions. (16-17) Without a characteristic fiber arrangement and composition for each fascial region, it is likely that fascia would not withstand stresses or have the same function.

The cells within fascia include fibrocytes (fibroblasts, myofibroblasts), adipocytes, and various migrating white blood cells. (27,41-42) Fibroblasts are highly adaptable to their environment, and show a capacity to remodel in response to the direction of various mechanical stimuli, producing biochemical responses. (29,41,43-45) If function changes, as with increased mechanical stress, or prolonged immobilization, deoxyribonucleic acid (DNA) transcription of pro-collagen in the fibroblasts will change types (e.g., collagen type I into collagen type III), or undifferentiated cell types may adapt towards a more functionally appropriate lineage (e.g., chondrocyte). (42,45-48)

Benjamin et al, studied the morphological changes observable in various tendons and ligaments in response to biomechanical stresses. (46) It was established that the tissue structure and the molecular composition of ECM are directly correlated with the local mechanical forces. (46,47) Under significant states of compression, tissue once populated with fibroblasts, becomes invested predominately with chondrocytes and forms specialized connective tissue, cartilage, with further solid mineral deposition. (46,47) These adaptations have been demonstrated in the supraspinatus tendon, transverse acetabular ligament, transverse ligament of atlas, as well as various other ligaments and tendons throughout the body. (47,48)

Myofibroblasts within fascia demonstrate contractile properties and contain actin-myosin filaments typically seen in smooth muscle. (49-51) The significance of these contractile properties remains unclear, however in-vitro observations of autonomous contraction of myofibroblasts harvested from porcine and rat fascia when stimulated with various pharmacological agents (i.e., mepyramine, angiotensine, glyceryltrinitrate) have been repeated in different labratories. (52-53) An estimation of tension created by contraction of myofibroblasts when extrapolated to a large fascial sheet (i.e., thoracolumbar fascia) may produce tension within the musculoskeletal system between 30-40N. (51) The significance of this contractile property remains hypothetical and reproduction of these contractile forces in-vivo in response to efferent neural stimulus is yet to be done.

Increased concentration of myofibroblasts in pathological fascia has been observed, suspected to create tissue contractures in clinical conditions like palmar fascial fibromatosis (Dupuytren's disease), plantar fascial fibromatosis (Ledderhose's disease), and adhesive capsulitis (frozen shoulder). (49,54-56) Fascia is also susceptible to the actions of typical cells of inflammation influencing communication, growth, and function. (37,38)

Fiber orientation in fascia is important to its overall structure and function, and can be viewed with the unaided eye, polarized light, or various microscopic techniques. (18,27,57) It is a consistent observation that the fibers are oriented parallel to predicted force vectors, and are likely to resist tension. (18,27,57) Based on certain common characteristics, including the fiber arrangement, connective tissue proper is classified by the Terminologia Histologica as loose connective tissue and dense connective tissue. (24) The dense connective tissue is sub-categorized as: i) unidirectional parallel ordered dense connective tissue, ii) multidirectional parallel ordered dense connective tissue, iii) woven connective tissue, iv) irregular fusocellular connective tissue. (24)

IV. Mechanotransduction

Mechanotransduction entails significant cellular change that occurs in response to biomechanical tension and compression. These stimuli exert their effects within the cells through filaments of the ECM, and so mechanical stimulation leads to a cascade of events which eventually influences the activity in the nucleus. (48,58,59) Mechanotransduction is produced as cells convert a diversity of mechanical stimuli, transmitted throughout the ECM, into chemical activity to regulate morphology and function of tissues. (60-61) The cellular responses include the release of interleukins, adhesion kinases and other biochemicals. (61-62)

Local injury in a tissue can have widespread consequences via mechanotransduction's role in stimulating quiescent cells to form active fibroblasts. (62) This mechanism of cellular activation via mechanical force has been hypothesized to play a role in embryological development as part of the induction process of mesenchymal cells throughout the mesoderm. (63) Clinically, the effects of mechanotransduction have been observed with the intervention of acupuncture. (64) There is evidence to suggest that the insertion of acupuncture needles into the fascia stimulates the activity of fibroblasts, presumably through physical strain exerted on the transmembranous microfilaments in the ECM. (65-66) Needles will also cause displacement of that tissue, and twisting of the needle once it is inserted can cause further displacement of the fascia as measured with ultrasonic elastomyography. (35) Simple manual pressure has also been demonstrated, through deformation, to cause alterations in the viscoelasticity of tissue. (30,36) These cellular and filamentous responses may provide a theoretical framework for the therapeutic mechanisms of soft tissue therapies. (36,67-68) An understanding of mechanotransduction reveals that for healing and injury it is not only the gross observable reaction of tissues that is of interest, but also the biomechanical response of the ECM within fascia.

V. Innervation

Electron microscopy and special staining procedures demonstrate that fascia is populated by sensory neural fibers, suggesting that fascia contributes to proprioception and nociception, and may be responsive to manual pressure, temperature, and vibration. (18,26,69,70) Some receptors found within fascia may be responsive to, and influence some autonomic responses, such as lowering blood pressure. (71-72)

On a structural basis, two classes of sensory receptors are recognized: free nerve endings as terminal branches of the axons, and encapsulated endings with distinctive arrangements of non-neuronal cells that completely enclose the terminal parts of the axons. (73) Some of these receptors function as both a mechanoreceptor and a nociceptor (types III and IV receptors). (73) Pain that arises in muscles, tendons, ligaments, and bones is detected by these receptors. There have been conflicting results in the research, but most recent evidence has revealed small diameter free nerve endings in the thoracolumbar fascia of rats and humans. (69) One investigation has revealed the presence of these fibers on electronmicroscopy (18), meanwhile another group has demonstrated calcitonin gene-related peptide (CGRP) and substance P (SP) within the same fibers, suggesting afferent function, including nociception. (69) Further work must be done on human specimens as currently the best evidence is heavily reliant on animal models.

Langevin et al, developed a pathophysiological model of low back pain based on connective tissue nociception, after demonstrating on ultrasound the structural alterations of the low back connective tissues. (34,70) Fascial connections within different motor units, and different functional synergists, can provide an alternative explanation for referred pain distributions, which often do not follow either nerve pathways or the morphology of a single muscle. (74)

Many encapsulated endings found in fascia are mechanoreceptors that respond to mechanical pressure or deformation, and include Golgi receptors, Pacinian corpuscles, and Ruffini's corpuscles. (18,26,75-76) Different techniques of tissue manipulation may stimulate the above receptors: the high-velocity thrust manipulations and vibratory techniques likely stimulate Pacinian receptors, while slow, deep soft tissue techniques likely target Ruffini's bodies. (75-76) Knowing what receptors are more significantly concentrated in a particular target tissue can help a manual practitioner choose the method of stimulus and technique (e.g., deep pressure, light stroke, stretch, tension, or vibration). (75-76) Understanding that certain types of fascia are more densely populated with certain particular receptors can aid in the overall understanding of the body and creating more effective approaches to manual treatments.

B. Classification System

In an effort to organize nomenclature for fascia provided by the FICAT, we developed a functional classification system which includes four categories of fascia: i) linking, ii) fascicular, iii) compression, and iv) separating fasciae.

All fascia-related terminology provided in the Terminologia Anatomica can be subsumed within these four categories (Table 1). (4) This system is not meant to be a reductionist approach to the fascial system, but a mode of exploring and better understanding the complex interaction of functions that exist within the system. Each region of the body contains multiple categories, suggesting that every region of the body has a complex mixture of different fascial types. To illustrate this concept, the thigh is an example of a body region which contains all four fascial categories: Illiotibial band (Linking), perimysium of the quadriceps femoris muscle (Fascicular), fascia lata (Compression), and subcutaneous tissue (Separating).

I. Linking Fascia

The linking category is predominantly dense regular parallel ordered unidirectional connective tissue proper with a significant amount of collagen type I. (16,24) This includes fasciae of muscles, fasciae of regions (head & neck, trunk, limbs), aponeuroses, tendinous arches and neurovascular sheaths. (4)

This category is subdivided into dynamic and passive divisions. The dynamic division includes major fascial groups more significantly related to movement and joint stability, and characterized by higher concentrations of contractile and proprioceptive fibers. The dynamic division is composed of fasciae of muscles (investing layer, fascia of individual muscle), and fasciae of the trunk. (4) The innervation of dynamic linking fascia functionally differentiates it from other categories, permitting it to contribute to nociception and proprioception. For example, the thoracolumbar fascia (TLF) contributes to spinal stability and makes firm connections between the trunk and limbs. (77) It is also densely innervated by free nerve endings and Paciniform corpuscles which respond to rapid pressure and vibration. (2,18,73,78)

The passive division is acted on by other extramuscular tissues to maintain continuity throughout the body or form tunnels and sheaths. (7) The passive division incorporates fasciae of muscles (muscle sheaths), fasciae of the head and neck, fasciae of limbs, aponeuroses, tendinous arches, and retinaculae. (4) This group can act as muscular insertion points, such as the epicranial aponeurosis, and as joint linkages and tendinous arches ultimately providing proprioceptive information when tension is exerted. (7) The passive linking fasciae can only transmit force when they are stretched and loaded, while dynamic fasciae can theoretically contract more autonomously like smooth muscle, thereby affecting tension in the musculoskeletal system, but not significant enough to be the primary mover of limbs. (51)

II. Fascicular Fascia

Fascicular fascia forms adaptable tunnels which bundle vessels as well as fascicles within muscle, tendon, bone and nerves. Fascicular fascia plays an important role in organization, transport, strength and locomotion. (39) This category is organized as a mixture of both loose and dense regular multidirectional connective tissues. (24) Types I and III collagen are the major components of these tissues with lesser amounts of Types V, VI, XII, and XIV. (16,39,79)

Fascicular fascia of the muscle comprises three distinct layers of IMCT: epimysium surrounding whole muscles, perimysium separating fascicles or bundles of muscle fibers within the muscle, and endomysium covering the individual muscle fibers. (39) Forming the muscle architecture, this network of collagen fibers can be seen as an extensive matrix of tunnels that connects and dissipates force within muscle, provides intramuscular pathways and mechanical support for large and small nerves, blood vessels and lymphatics. (32,39,79) The fascicular fascia of the muscle converges into a dense regular connective tissue link at the myotendinous junction to become fascicular fascia of the tendon, comprising endotendon, peritendon and epitendon. (5,7,79) At this junction, fascicular fascia is richly innervated by Golgi tendon organs which are stimulated by muscle contraction. (37,38) Tension in the tendon results in a reflex decrease in tonus in contiguous striated muscle fibers. (70)

IMCT is essential for myofascial force transmission (as outlined in Results section A I), enhancing the forces produced by muscles. (8) Fascicular fasciae allow forces to be transferred from within muscle to synergistic muscles, and also, via the extramuscular pathway, through the linking fascia, to antagonistic muscles. (8,13-14) The fascicular fascia forms the connective tissue envelope for nerve fascicles and whole peripheral nerves: perineurium and epineurium, respectively. (37,38) The perineurium serves as a metabolically active diffusion barrier that contributes to the formation of a blood-nerve barrier. (80) The blood vessels that supply the nerves travel in the epineurium. (80) These two layers of the fascicular fascia are innervated by the nervi nervorum, which can evoke nociception through the release of CGRP and may create neurogenic inflammation. (81) An inflammation of the nervi nervorum causes the inflammatory reaction of the nerve's fascial envelopes to induce the mechanical sensitivity, which can manifest as local, radicular, or neuropathic pain. (75,82,83)

III. Compression Fascia

Compression fascia is a mixture of dense regular woven and multidirectional parallel ordered connective tissue layers that ensheath whole limbs to create a stocking effect. (24,84) This fascial category plays an important role in locomotion and venous return due to its influence on compartmental pressure, muscle contraction and force distribution. (20,29,84) For example, the crural fascia is composed of two or three layers of parallel ordered collagenous fiber bundles, each layer being separated by a thin layer of loose connective tissue. (19,29) The spatial orientation of the collagen fibers changes from layer to layer within the compression fascia. (29) The presence of loose connective tissue interposed between adjacent layers permits local sliding, allowing the single layers to respond more effectively. (29)

Examples of this type of fascia are observed in the limbs and are observed as fascia lata, crural fascia, brachial fascia, and antebrachial fascia. While there are proprioceptors embedded in this fascia, its role as a sensory organ is less significant than that of the linking, or fascicular categories.

IV. Separating Fascia

Separating fascia is generally loose connective tissue and dense irregular fusocellular connective tissue. (24) The reticular Type III collagen fibers and elastic fibers are the major components of the ECM of separating fascia, with small amounts of collagen Types V, VII. (16-17) While the reticular fibers provide a supporting framework for the cellular constituents, the elastic fibers form a three-dimensional network to allow separating fascia to respond to stretch and distention. (28,37) Separating fascia divides the body in visible sheets and layers of varying fibers allowing it to take up forces and friction in all directions. While its major function is to allow more efficient sliding of tissues over one another, it may still form adhesions from faulty movement patterns or injury. (54)

FICAT's terms for separating fascia include: parietal fascia, visceral fascia, extraserosal fascia, investing/subcutaneous fascia, formerly known as fascia superficialis. (4) This category also includes synovial sheaths and fasciae of limbs. (4) Parietal fascia lies outside the parietal layer of serosa such as pericardium, pleura and peritoneum, and lines the wall of a body cavity. (4) Visceral fascia lies immediately outside the visceral layer of the serosa and surrounds the viscera. (4,85) Extraserosal fascia lies within the space between the visceral and parietal fasciae. (4)

This fascia class is a complex connective tissue matrix, ensheathing everything from body cavities to individual organs. It separates, supports, and compartmentalizes organs and regions in order to maintain proper structural and functional relationships throughout the body. This group of fascia has a unique appearance and texture upon observation, ranging from transparent woven sheets to a fuzzy cotton-like consistency. (28)

The innervation of separating fascia serves primarily to sense distension and compression of tissues. More detailed histological analyses are necessary to reveal with certainty the fascial innervations of these deep layers. However, concentrations of Pacinian corpuscles (detecting deep pressure) and Ruffini's corpuscles, which responding slowly to sustained pressure and tangential forces, are thought to be present in much of separating fascia, for example, in subcutaneous tissue. (28,70,86) Deep sustained pressure may be necessary for manual practitioners to affect this fascial tissue.


Through this article, we have reviewed advances in fascia research and addressed issues related to terminology and classification of fascia. The literature supports defining fascia as an innervated, continuous, functional organ of stability and motion that is formed by 3-dimensional collagen matrices. In an effort to organize the nomenclature of fascia, we devised a functional classification system which includes four categories of fascia: i) linking, ii) fascicular, iii) compression, and iv) separating fasciae.

These categories were developed based primarily on the functional properties of fasciae, with further observations from the literature on gross anatomical, histological and biomechanical features, and terms unique to each category. Such a classification system based on functional properties of fasciae may have more relevance to the clinical experiences of manual therapists.

All fascial related terminology provided in the Terminologia Anatomica (4) can be subsumed within these four fascial categories (Table 1).

Each region of the body contains multiple categories. This suggests that the complex interaction of different fascial types improves the musculoskeletal system's efficiency. It is our hope that this classification system will add clarity, improve diagnostic precision and contribute to manual therapists' understanding of fascia as a target of pathology and treatment.


(1.) LeMoon K. Terminology used in Fascia Research. J Bodyw Mov Ther. 2008; 12(3):204-212.

(2.) Yahia L, Pigeon P, DesRosiers E. Viscoelastic properties of the human lumbodorsal fascia. J Biomed Eng. 1993; 15(5):425-429.

(3.) Stecco A, Macchi V, Stecco C, et al. Anatomical study of myofascial continuity in the anterior region of the upper limb. J Bodyw Mov Ther. 2009; 13(1):53-62.

(4.) Terminologia Anatomica: international anatomical terminology. Federative Committee of Anatomical Terminology (FCAT). Stuttgart, New York: Thieme, 1998:1-292.

(5.) Langevin H, Huijing P. Communicating about fascia: history, pitfalls and recommendations. Int J Ther Massage Bodywork. 2009; 2(4):3-8.

(6.) Mirkin S. What is fascia? Unveiling an obscure anatomical construct. J Bodyw Mov Ther. 2008; 12(4):391-392.

(7.) van der Wal J. The architecture of the connective tissue in the musculoskeletal system--an often overlooked functional parameter as to proprioception in the locomotor apparatus. Int J Ther Massage Bodywork. 2009; 2(4):9-23.

(8.) Huijing PA. Epimuscular myofascial force transmission: historical review and implications for new research. International society of biomechanics Muybridge award lecture, Taipei. J Biomechanics. 2009; 42(1):9-21.

(9.) Stecco A, Masiero S, Macchi V, et al. The pectoral fascia: anatomical and histological study. J Bodyw Mov Ther. 2009; 13(3):255-261.

(10.) Ophir J, Cespedes I, Ponnekanti H, et al. Elastography: a quantitative method for imaging the elasticity of biological tissues. Ultrasound Imaging. 1991; 13:111-134.

(11.) Standring S, editor. Gray's Anatomy: The Anatomical Basis of Clinical Practice. 40th. ed. Churchill-Livingstone, Elsevier, 2008:1-1576.

(12.) Langevin H, Rizzo D, Fox J, et al. Dynamic morphometric characterization of local connective tissue network structure in humans using ultrasound. BMC Systems Biology. 2007; 1:25.

(13.) Huijing PA, van de Langenberg R, Meesters J, Baan G. Extramuscular myofascial force transmission also occurs between synergistic muscles and antagonistic muscles. J Electromyogr Kinesiol. 2007; 17(6):680-689.

(14.) Huijing PA. Epimuscular myofascial force transmission between antagonistic and synergistic muscles can explain movement limitation in spastic paresis. J Electromyogr Kinesiol. 2007; 17(6):708-724.

(15.) Huijing P, Baan G. Extramuscular myofascial force transmission within the rat anterior tibial compartment: proximo-distal differences in muscle force. Acta Physiol Scand. 2001; 173:297-311

(16.) Gordon M, Hahn R. Collagens. Cell Tissue Res. 2010; 339(1):247-257.

(17.) Gelse K, Poschl E, Aigner T. Collagens-structure, function, and biosynthesis. Adv Drug Deliver Rev. 2003; 55:1531-1546.

(18.) Yahia L, Rhalmi S, Newman N, Isler M. Sensory innervation of human thoracolumbar fascia. An immunohistochemical study. Acra Orthop Scad. 1992; 63(2):195-197.

(19.) Benetazzo L, Bizzego A, De Caro R, et al. 3D reconstruction of the crural and thoracolumbar fasciae. Surg Radiol Anat. 2011. Published Online 4 January. Doi:10.1007/s00276-010-0757-7.

(20.) Caggiati A. Fascial relations and structure of the tributaries of the saphenous veins. Surg Radiol Anat. 2000; 22:191196.

(21.) Hocking D, Titus P, Sumagin R, Sarelius I. Extracellular matrix fibronectin mechanically couples skeletal muscle contraction with local vasodilation. Circ Res. 2008; 102(3):372-379.

(22.) Wendell-Smith C. Fascia: An illustrative problem in international terminology. Surg Radiol Anat. 1997; 19(5):273-277.

(23.) Ercoli A, Delmas V, Fanfani F, et al. Terminologia Anatomica versus unofficial descriptions and nomenclature of the fasciae and ligaments of the female pelvis: a dissection-based comparative study. Am J Obstet Gynecol. 2005; 193(4):1565-1573.

(24.) Terminologia Histologica. International terms for human cytology and histology/ Federative International Committee on Anatomical Terminology (FICAT). Baltimore: Wolters Kluwer/Lippincott Williams & Wilkins, 2008:1-207.

(25.) De Zordo T, Lill SR, Fink C, et al. Real-time sonoelastography of lateral epicondylitis: comparison of findings between patients and healthy volunteers. AJR. 2009; 193:180-185.

(26.) Stecco C, Gagey O, Belloni A. Anatomy of the deep fascia of the upper limb. Second part: study of innervation. Morphologie. 2007; 91(292):38-43.

(27.) Stecco C, Porzionato A, Lancerotto L, et al. Histological study of the deep fascia of the limbs. J Bodyw Mov Ther. 2008; 12(3):225-230.

(28.) Hedley G. Demonstration of the integrity of human superficial fascia as an autonomous organ. J Bodyw Mov Ther. 2008; 12(3):258.

(29.) Stecco C, Pavan P, Porzionato A, et al. Mechanics of crural fascia: from anatomy to constitutive modeling. Surg Radiol Anat. 2009; 31(7):523-529.

(30.) Chaudhry H, Schleip R, Ji Z, Bukiet B, Maney M, Findley T. Three-dimensional mathematical model for deformation of human fasciae in manual therapy. J Am Osteopath Assoc. 2008; 108(8):379-390.

(31.) Huijing PA, Hollander P, Findley T, Schelip R, eds. Proceedings of the 2nd International Fascia Research Congress. Fascia Research II: Basic Science and Implications for Conventional and Complementary Health Care. Munich: Elsevier, 2009:1-11.

(32.) Guimberteau J, Delage J, McGrouther D, Wong J. The microvacuolar system: how connective tissue sliding works. J Hand Surg Eur. 2010; 35(8):614-622.

(33.) Guimberteau J, Sentucq-Rigall J, Panconi, B. Introduction to the knowledge of subcutaneous sliding system in humans. Ann Chir Plast Esth. 2005; 50(1):19-34.

(34.) Langevin H, Stevens-Tuttle D, Fox J, et al. Ultrasound evidence of altered lumbar connective tissue structure in human subjects with chronic low back pain. BMC Musculoskelet Disord. 2009; 10(1):151.

(35.) Langevin H, Konofagou E, Badger G, et al. Tissue displacements during acupuncture using ultrasound elastography techniques. Ultrasound Med Biol. 2004; 30(9):1173-1183.

(36.) Chaudhry H, Huang C, Schleip R, et al. Viscoelastic behavior of human fasciae under extension in manual therapy. J Bodyw Mov Ther. 2007; 11(2):159-167.

(37.) Ross MH, Pawlina P. Histology: a text and atlas: with correlated cell and molecular biology.6th ed. Baltimore: Wolters Kluwer/Lippincott Williams & Wilkins, 2011:158-217.

(38.) Gartner L, Hiatt J. Color Textbook of Histology.3rd. ed. Edinburgh: Saunders & Elsevier, 2007:1-592.

(39.) Purslow P. The structure and functional significance of variations in the connective tissue within muscle. Comp Biochem Phys A. 2002; 133(4):947-966.

(40.) Koz'ma K, Olczyk K, G1owacki A, Bobinski R. An accumulation of proteoglycans in scarred fascia. Mol Cell Biochem. 2000; 203(1-2):103-112.

(41.) Chirasatitsin S, Engler AJ. Detecting cell-adhesive sites in extracellular matrix using force spectroscopy mapping. J Phys Condens Matter. 2010; 22(19). Doi:10.1088/0953-8984/22/19/194102.

(42.) Jarvinen TA, Jozsa L, Kannus P, et al. Organization and distribution of intramuscular connective tissue in normal and immobilized skeletal muscles. An immunohistochemical, polarization and scanning electron microscopic study. J Muscle Res Cell Motil. 2002; 23(3):245-254.

(43.) Eagan T, Meltzer K, Standley P. Importance of strain direction in regulating human fibroblast proliferation and cytokine secretion: a useful in vitro model for soft tissue injury and manual medicine treatments. JMPT. 2007; 30(8):584-592.

(44.) Meltzer K, Thanh V, Cao B. In vitro modeling of repetitive motion injury and myofascial release. J Bodyw Mov Ther. 2010; 14:162.

(45.) Mammoto A, Ingber D. Cytoskeletal control of growth and cell fate switching. Curr Opin Cell Biol. 2009; 21(6):864-870.

(46.) Benjamin M, Ralphs JR. Fibrocartilage in tendons and ligaments-an adaptation to compressive load. J Anat. 1998; 193(4):481-494.

(47.) Milz S, Benjamin M, Putz R. Molecular parameters indicating adaptation to mechanical stress in fibrous connective tissue. Adv Anat Embryol Cell Biol. 2005; 178:1-71.

(48.) Bank R, TeKoppele J, Oostingh G, Hazleman B, Riley G. Lysylhydroxylation and non-reducible crosslinking of human supraspinatus tendon collagen: changes with age and in chronic rotator cuff tendinitis. Ann Rheum Dis. 1999; 58:35-41.

(49.) Klinge U, Si ZY, Zheng H, Schumpelick V, et al. Collagen I/III and matrix metallopro-teinases (MMP) 1 and 13 in the fascia of patients with incisional hernias. J Invest Surg. 2001; 14(1):47-54.

(50.) Schleip R, Rankl S, Zorn A, et al. Myofibroblast Density in Fasciae. In: Huijing PA, Hollander, P, Findley, T, Schelip, R, eds. Proceedings of the 2nd International Fascia Research Congress. Fascia Research II: Basic Science and Implications for Conventional and Complementary Health. Munich: Elsevier; 2009:1-219.

(51.) Schleip R, Klingler W, Lehmann-Horn F. Active fascial contractility: Fascia may be able to actively contract in a smooth muscle-like manner and thereby influence musculoskeletal dynamics. Med Hypotheses. 2005; 65:273-277.

(52.) Masood N, Naylor IL. The in vitro reactivity of fascia from the rat and guinea-pig to calcium ions and mepyramine. Br J Pharmacol. 1994;112:416P.

(53.) Masood N, Naylor IL. Effect of adenosine on rat superficial and deep fascia and the effect of heparin on the contractile responses. Br J Pharmacol. 1994;113:112.

(54.) Hedley G. Notes on visceral adhesions as fascial pathology. J Bodyw Mov Ther. 2010; 14(3):255-61.

(55.) Gabbiani G, Majno G. Dupuytren's contracture: fibroblast contraction? An ultrastructural study. Am J Pathol. 1972; 66:131-146.

(56.) Bunker T. Time for a new name for frozen shoulder-contracture of the shoulder. Shoulder & Elbow. 2009; 1(1):4-9.

(57.) Gerlach, UJ, Lierse, W. Functional construction of the superficial and deep fascia system of the lower limb. Acta Anat. 1990; 139(1):11-25.

(58.) Ingber DE. Tensegrity I. Cell structure and hierarchical systems biology. J Cell Sci. 2003; 116:1157-1173.

(59.) Engler A, Sen S, Sweeney H,, Discher D. Matrix elasticity directs stem cell lineage specification. Cell. 2006; 126(4):677-689.

(60.) Katsumi A, Orr AV, Tzima E, Schwartz MA. Integrins in mechanotransduction. J Biol Chem. 2004; 279(13):12001- 12004.

(61.) Ingber DE. Mechanosensation through integrins: Cells act locally but think globally. Proc Natl Acad Sci USA. 2003; 100(4):1472-1474.

(62.) Langevin H. Connective tissue: A body-wide signaling network? Medical Hypothesis. 2006; 66(6):1074-1077.

(63.) Lelean P.The migratory fascia hypothesis. J Bodyw Mov Ther. 2009; 13(4):304-310.

(64.) Langevin H, Churchill D, Cipolla M. Mechanical signaling through connective tissue: a mechanism for the therapeutic effect of acupuncture. FASEB J. 2001; 15(12):2275-2282.

(65.) Langevin H, Bouffard N, Badger G, Churchill D, Howe A. Subcutaneous tissue fibroblast cytoskeletal remodeling induced by acupuncture: Evidence for a mechanotrasduction -based mechanism. J Cell Phys. 2006; 207:767-774.

(66.) Julias M, Edgar L, Buettner H, Shreiber D. An in vitro assay of collagen fiber alignment by acupuncture needle rotation. BioMedical Engineering OnLine. 2008; 7(19).

(67.) Barnes M. The Basic Science on myofascial release: morphological change in connective tissue. J Bodyw Mov Ther. 1997; 1(4):231-238.

(68.) Simmonds N, Miller P, Gemmell H. A theoretical framework for the role of fascia in manual therapy. J Bodyw Mov Ther. 2010; doi:10.1016/j.jbmt.2010.08.001.

(69.) Tesarz J, Hoheisel U, Wiedenhofer B, Mense S. Sensory innervation of the thoracolumbar fascia in rats and humans. Neuroscience. 2011;194:302-308.

(70.) Langevin H, Sherman K. Pathophysiological model for chronic low back pain integrating connective tissue and nervous system mechanisms. Med Hypotheses. 2007; 68(1):74-80.

(71.) Coote J, Perez-Gonzalez J. The response of some sympathetic neurons to volleys in various afferent nerves. J Physiol. 1970; 208(2):261-278.

(72.) Mitchell J, Schmidt R. Cardiovascular reflex control by afferent fibers from skeletal muscle receptors. In: Shepherd J, Abboud F, eds. Handbook of Physiology section 2, The Cardiovascular System. III. Bethesda: American Physiological Society, 1983:623-658.

(73.) Kiernan JA. Barr's the human nervous system: an anatomical viewpoint.9th.ed. Baltimore: Wolters Kluwer/ Lippincott Williams & Wilkins, 2009:35-48.

(74.) Han D. The other mechanism of muscular referred pain: The "connective tissue" theory. Med Hypotheses. 2009; 73(3):292-295.

(75.) Schleip R. Fascial plasticity--a new neurobiological explanation: Part 1: J Bodyw Mov Ther. 2003; 7(1):11-19.

(76.) Schleip R. Fascial plasticity--a new neurobiological explanation: Part 2. J Bodyw Mov Ther. 2003; 7(2):104-116.

(77.) Vleeming A, Pool-Goudzwaard AL, Stoeckart R, et al. The posterior layer of the thoracolumbar fascia, its function in load transfer from spine to legs. Spine. 1995; 20(7):753- 758.

(78.) Barker P, Guggenheimer K, Grkovic I, et al. Effects of tensioning the lumbar fasciae on segmental stiffness during flexion and extension. Spine. 2006; 31(4):397-405.

(79.) Loukas M, Shoja M, Thurston T, Jones V, et al. Anatomy and biomechanics of the vertebral aponeurosis part of the posterior layer of the thoracolumbar fascia. Surg Radiol Anat. 2008; 30(2):125-129.

(80.) Passerieux E, Rossignol R, Chopard A, et al. Structural organization of the perimysium in bovine skeletal muscle: Junctional plates and associated intracellular subdomains. J Struct Biol. 2006; 154(2):206-216.

(81.) Bove G. Epi-perineurial anatomy, innervation, and axonal nociceptive mechanisms. J Bodyw Mov Ther. 2008; 12 (3):185-190.

(82.) Sauer SK, Bove M, Averbeck W. Rat peripheral nerve components release calcitonin gene-related peptide and prostaglandin e2 in response to noxious stimuli: evidence that nervi nervorum are nociceptors. Neuroscience. 1999; 92(1):319-325.

(83.) Bove GM, Light AR. The nervi nervorum: missing link for neuropathic pain? Pain Forum. 1997; 6:181-190.

(84.) Fourie W. Fascia lata: Merely a thigh stocking, or a coordinator of complex thigh muscular activity? J Bodyw Mov Ther. 2008; 12(3):265.

(85.) Johnson G, Zhang M, Barnett R. A Comparison between Epoxy Resin Slices and Histology Sections in the Study of Spinal Connective Tissue Structure. J Int Soc Plastination. 2000; 15(1):10-13.

(86.) Abu-Hijleh M, Roshier A, Al-Shboul Q, et al. The membranous layer of superficial fascia: evidence for its widespread distribution in the body. Surg Radiol Anat. 2006; 28(6):606-619.

Myroslava Kumka, MD, PhD *

Jason Bonar, BScKin, DC

* Canadian Memorial Chiropractic College, Department of Anatomy

Correspondence should be addressed to: Myroslava Kumka, 6100 Leslie Street, Toronto ON M2H 3J1, Canada Tel: 416-482-240 ext: 175

Table 1 Fascial categories: function, terms, and
histological features

Fascial              Function

Lingking   Dynamic
                     -- role in movement and

                     -- critical to
                     myofascial force

                     -- creates significant
                     pretension in

                     -- maintains continuity,
                     passive force

                     -- proprioceptive
                     throughout the body

Fascicular           - provides myofascial
                     force transmission &
                     proprioceptive feedback
                     for movement control

                     - maintains protection for
                     nerves and vessels

                     - allows vascular sheaths
                     to be in continuity with

                     -- provides stocking,
                     compression and tension
                     compartmental effects

                     -- influences venous return

                     -- enhances proprioception,
                     muscular efficiency
                     and coordination
                     -- compartmentalizes
                     organs and body regions
                     to maintain structural

                     -- promotes sliding and
                     reduces friction during

                     -- responds to stretch and

                     -- provides physical
                     support and shock

                     -- limits the spread of

Fascial              (Examples)
category             Terminologia Anatomica (4)

Lingking   Dynamic   Fasciae of muscles (investing layer)
                     & fasciae of individual muscles:
                     Pectoral fascia
                     Supraspinatus fascia
                     Deltoid fascia

                     Fasciae of trunk:
                     Thoracolumbar fascia
                     Diaphragmatic fascia
                     Iliopsoas fascia

                     Fasciae of limbs/membrorum
                     Iliotibial tract
                     Axillary fascia
           Passive   Fasciae of muscles (muscle sheath)
                     Rectus sheath

                     Head & Neck
                     Cervical fascia
                     Carotid sheath
                     Ligamentum nuchae
                     Ligamentum flavum

                     Fasciae of limbs/membrorum
                     Intermuscular septae
                     Anterior talofibular ligament
                     Erector spinae aponeurosis
                     Bicipital aponeurosis
                     Plantar aponeurosis
                     Tendinous arches
                     Muscular & vascular spaces/lacunae
                     Iliopectineal arch
                     Tendinous arch of soleus
Fascicular           Intramuscular & extramuscular
                     fasciae. Neurovascular sheaths


Compression          Fasciae of limbs/membrorum
                     Brachial fascia
                     Antebrachial fascia
                     Dorsal fascia of hand
                     Fascia lata
                     Crural fascia
                     Dorsal fascia of foot

Separating           Parietal Fascia
                     Parietal pleura
                     Fibrous pericardium
                     Endothoracic fascia
                     Parietal peritoneum
                     Endoabdominal fascia
                     Endopelvic fascia

                     Visceral fascia
                     Visceral pleura
                     Serous pericardium
                     Visceral peritoneum
                     Visceral abdominal fascia
                     Visceral pelvic fascia

                     Extraserosal fascia
                     Sternopericardial ligaments
                     Bronchopericardial membrane
                     Pulmonary ligaments
                     Extraperitoneal fascia
                     Investing fascia
                     Subcutaneous tissue of abdomen
                     Membranous layer of perineum

Fascial              Terminologia
category             Histologica (24)

Lingking   Dynamic   Dense regular
                     parallel ordered
                     connective tissue

           Passive   Dense regular
                     connective tissue

                     parallel ordered
                     connective tissue

Fascicular           Loose
                     connective tissue

                     Dense regular
                     parallel ordered
                     connective tissue

                     Dense irregular
                     connective tissue

Compression          Dense regular
                     connective tissue

                     parallel ordered
                     connective tissue

Separating           Loose
                     connective tissue

                     Dense irregular
                     connective tissue

Fascial              Histological
category             features (16,37)

Lingking   Dynamic   Collagen types:
                     I, XII, XIV


                     Free nerve

           Passive   Collagen types:
                     I, III, XII, XIV


                     Golgi tendon
                     organs, Pacinian
                     & Ruffini's

Fascicular           Collagen types:
                     I, III, IV, V,
                     XII, XIV

                     Golgi tendon

Compression          Collagen type I



Separating           Collagen types:
                     III, V, VII

                     matrix: reticular
                     and elastic fibers

                     fibers provide
                     a cellular


                     Pacinian and
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Author:Kumka, Myroslava; Bonar, Jason
Publication:Journal of the Canadian Chiropractic Association
Article Type:Report
Date:Jul 1, 2012
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