ABSTRACT In this article, Dr. Carla Stecco describes the application of cadaver studies for manual therapy, the histology of fascia, and the innervation of fascia.
Editor’s note: This interview was conducted in person on September 9th, 2022, a day before the start of the Sixth International Fascia Research Congress held in Montréal, Canada.
Carla Stecco, MD is a world-renowned fascia specialist. As an orthopedic surgeon and professor of human anatomy and movement sciences at the University of Padova in Italy, she has published over a hundred and eighty peer-reviewed fascia articles and authored several books on the subject. She has focused her expertise on describing the nature of human fascia and the cellular organization of the microscopic environment of fascia. Also, Stecco teaches fascia-oriented cadaver dissections to manual therapists and physicians to further our understanding of the nature of fascia.
Lina Amy Hack: Thank you so much Dr. Stecco for meeting with me today. Let’s dive in with my first question, how much can a manual therapist infer from the study of cadavers to the real-life application of working with their clients?
Carla Stecco: Thank you for inviting me to speak with you. Yes, this is a good question. I think that it is really important for every manual therapist to attend a human dissection course at least once because, just as with anatomical pictures, we cannot see certain things looking at a person. We don’t get an understanding from anatomy atlas pictures of the depth of the structures that we are to reach.
In manual therapy, every time we touch a body we interact with the skin. The skin has a particular thickness that can be clearly observed with dissection. Also, manual therapists need to interact with the fascia – the superficial fascia, the deep fascia, the blood vessels, and the nerves – then relate these structures to the muscles, joints, and bones. When I teach dissection, I want to help people have a clearer idea about all these body structures in order to develop details in their mental picture of the body that they may not have had before.
Besides this, in anatomy books we have drawings of muscles that are big, very evident, and have a good shape. Does every person have structures like this? When we touch, we need to be sure that we are contacting the layer we think we are reaching, and that we also understand the fibers of the muscle and their directions (see Figure 1). When we look at the details of a donor cadaver, we start to understand that the muscles in some people, are not so big. There are also a lot of structures that we need to take into consideration, sometimes what we touch is not exactly what we think we are feeling.
LAH: Right, as a Rolfer®, I imagine what is under the skin, but what we feel may not be what we think it is. Cadaver classes teach us what is really there and what would be better to imagine while we work with our clients.
CS: We need to have a better knowledge of what we are doing and it is important to think about how we can really do that learning. In general, a little bit of cadaver study is really important for practitioners.
LAH: What conclusions would you caution manual therapists against making from cadaver studies? What limits are there to studying cadaver tissue?
CS: Ah yes. You don’t have the tonus of living tissue, you don’t have the blood perfusion, and you have different gliding between the layers. As a result, you have some directions of inquiry that are quite different. It is for this reason that I always suggest to also use a different tool to study the fascia and not just cadavers. The cadaver does permit us to analyze human fascia, but it is not exactly as it is in the living body. With ultrasound, we can check the fascia in the living tissue, but without cadaver studies as well, we may not be able to interpret the ultrasound picture correctly.
Histology [the study of the microanatomy of tissues, as seen through a microscope] can also give us a lot of information, but it can be too much detail if we don’t also have a clear idea of the different layers of the body – the different structures. So only by combining the different points of view, can we then really understand human structure. But the cadaver is the base of the pyramid; it is the first step to building our knowledge of the fascia.
LAH: What I hear you saying is that cadaver studies can give a good foundation for understanding the human body. That has been my experience too.
Fascia is becoming more well known by the public, yet there is a range of qualities that the word fascia encompasses. It is one word, but it can mean different things to different professionals. What should we do about this?
CS: That is a huge problem. I still remember when I guided the discussion about the new definition of fascia in 2014, and it was really difficult work to put it together when there were so many different opinions about it. But from that point, we have been converging to a much clearer understanding of the fascia. Still, it is a new topic, so there are still different points of view. We did the correct exploration by inviting a wide range of colleagues to collaborate on the conversation of defining fascia. We are going in a certain direction and I think that it is the correct direction. Surely, fascia is much more complex than we thought at the beginning and it’s not easy to create a definition that describes it all. At the same time, with better knowledge, we are converging on a clear definition
that is not just opinion but more scientific (see Figure 2).
LAH: You wrote in Functional Atlas of the Human Fascia System (2015) that conditions, which the medical community labels as ‘non-specific pain’, may be pathology within a region or even part of a global aspect of the fascial net. Can you tell us what you think the fascial contribution is to non-specific pain?
CS: Yes, I think that every time we hear a diagnosis of non-specific pain, it is probably because we have forgotten to consider the fascia. Every day, my physician colleagues check the bone very well, they check the ligament to the joint and the muscle, but as we consider all the possibilities for pain and dysfunction, we must also consider the superficial fascia and the fascial system. If we consider the fascia, then the pain will not be non-specific any longer, as it will now finally have a name and it will be specific. And then we can talk about the structure that can create that pain and we can focus on better treatment. Only if we understand the original pain can we give an effective treatment. Otherwise, we can only give symptomatic treatment, which may never go to the underlying reasons for the pain.
I think that fasciae can reliably play a key role in pain because they are very well innervated. I started with this topic in one of my first publications, the innervation of the fascia, and I have published many different papers about fascial innervation (Stecco et al. 2006, Stecco et al. 2007, Stecco et al. 2013). And really, the fascia is one of the most innervated tissues that we have in our body, so if it is aggravated, it can surely generate a lot of pain. It is not just the muscular fascia that is perfect for perceiving pain, but also the visceral fascia, superficial fascia, and neural fascia that can generate pain and symptoms.
Remember that fascia has autonomic innervation and could create symptoms. Autonomic innervation can cause an alteration to our whole state. We can have many aspects perceived by the fascia not just the pain perception, but we should consider all the other sensory aspects when studying all the different aspects of the fascia. Innervation and sensation in the fascia system will continue to be very interesting to study in the future.
LAH: When you first started your career, was there a clear definition of fascia?
CS: When I started, I was interested in fascia because of my father [Luigi Stecco, Italian physiotherapist and author] and his Fascia Manipulation® Method. He always spoke about fascia. In his clinical practice, I saw the efficacy of fascial treatment. It was enough to convince me of its importance and so when I started medicine, when I started doing surgery (see Figure 3), I was also considering the ideas and results of my father’s work. I would say to myself, “Okay, clearly, there is something that is missing in medicine.” Yet, when I decided to study the fascia, there was nothing clearly describing the fascia, it was just considered an envelope of the muscle.
LAH: When I first started learning about fascia, it wasn’t considered innervated. It was almost talked about as a dead tissue.
CS: Exactly. When I started to consider studying fascia in my anatomy research, there were only a few papers describing connective tissue. One was about a pathological sample where the author was not sure if it was a pathological thinning by the nerve inside the fascia, and another one wrote about the possibility of innervation but the results were uncertain.
So, for that reason, my paper about the innervation of the fascia demonstrated that in every research subject there were nerve fibers inside the fascia. This was important at that time because, for the first time, we were saying that fascia is not just a dead envelope but probably has some functions – some perception. For three or four years I wondered if I had made some mistake, but then other groups of researchers also found these nerves and now we are sure that the fascia is innervated.
LAH: Yes, and now that has become common knowledge.
CS: Exactly. At the time, not so much.
LAH: Was there resistance for you as you were going into this area of anatomy study? Is it unconventional to be studying fascia?
CS: There is still resistance. Sometimes it seems I have to fight every week.
LAH: As a researcher then, I imagine a big part of your work is defending this line of inquiry to earn funding?
CS: It can be dramatic. Fortunately, we are now organizing dissection courses with McGill University here in Montréal, Quebec. This allows us to communicate about foundational fascia research. Fascia as a research area is still considered alternative, and it is never listed in the topics where you can submit for research grants. For the first time this year, the NIH [National Institutes of Health; medical research agency in the United States] published a grant about myofascial pain, but it is the first time.
LAH: Wow, so we’re still at the beginning in a way.
CS: Yes, because until this year, around the world there were no grants to study myofascial pain. Fortunately, I found a new group of professionals in the medical field who are interested in fascia research. Anesthesiologists are starting to be interested in fascia, pain doctors are starting to be interested in fascia; plastic surgeons are also paying attention; and radiologists are starting to describe the fascia and fascial directions. So, there is some movement.
Only if we move fascia research into universities and speak about fascia in university courses can we change the understanding of medical professionals. For the first few years of my fascia research, I found a great family of researchers from all over the world, and it has been amazing. But now it is time to take this understanding and go inside all the universities: to push in that direction, to expand who has this knowledge, to include fascia in all human anatomy courses, and to focus the research direction to consider fascia along with everything else.
LAH: Makes sense, we need to inspire the next generation of researchers to choose it.
CS: Yes, the researchers, but also the family doctors. We want them to think about the fact that there is fascia that they can check in a different way for the patient. Because patients are really tired of being only considered as ‘a knee’ or as ‘a hip’. The patient understands that their body is connected, and that their sore knee is somehow related to their sore hip.
LAH: So true. Switching back to defining fascia, your fascia atlas says, “Fascia is a proper organ system with its unique macroscopic and histological aspects and its own functions and pathologies” (Stecco 2015, viii). I was wondering why do you exclude joint capsules, ligaments, tendons, and loose connective tissue from your definition of fascia?
CS: You could debate this, yes. But my position is to be very precise when defining fascia. If I do a histological section and histological study, I need to know exactly what I am studying. If the definition is too general, my study won’t be able to be compared to the studies done by others. The histology of a tendon and the histology of superficial fascia are not the same at all – they are very different. So, we need to understand, that they are surely in continuity and they work together, but they are not the same structure. Because from a histological point of view they are quite different. And that is my position. Histology of fascia leads us to need precision with the terminology.
LAH: And when you say the histological point of view, you mean the types of cells that are there, how many of them, and their organization, plus the contents of the extracellular matrix?
CS: Yes, and also the type of nerve endings and the vascular differences. There are many different aspects to consider when describing what fascia is and what structures are excluded from the fascia definition. In the past, a journal rejected one of my research papers because they said that the definition of fascia was not clear. They said they didn’t know what I was specifically referring to because my definition of fascia was too general, and I had to work to understand their perspective.
LAH: I see, if we use a definition that is too broad, then other professionals that we are trying to communicate with won’t know exactly what we are talking about.
CS: Exactly. We need to be precise when we speak about fascia, and then we need to underline how fascia works like a bridge between many different structures. Fascia interacts with the tendon, it interacts with the joint capsule, but it is not the same structure.
LAH: Speaking of the cellular environment of fascia then, what is a fibroblast?
CS: The fibroblast is one of the most common cells that we have in our body because connective tissue is one of the most common tissues we have in our body (see Figure 4). The key cell in connective tissue is the fibroblast. The main function of fibroblasts is to maintain the structure of the connective tissue by releasing collagen and elastic fibers into the extracellular matrix.
Fibroblasts can activate and become a myofibroblast. Maybe it can also become a fasciacyte. We don’t know the organization but it probably can. We don’t know the relationship between the fibroblast and the telocytes (Dawidowicz et al. 2016). It is a new type of cell that was discovered in the fascia. The fibroblast is usually the final cell; under normal conditions, it is not going to have further differentiation.
LAH: A myofibroblast is downstream of a fibroblast. My understanding is that a fibroblast might get triggered into becoming a myofibroblast by stress
CS: Yes, surely it is a change in the environment that is going to trigger the transformation, for example, inflammation. The myofibroblast is the cell found in scar tissue, so when the tissue needs to be closed after an injury, the fibroblast activates to become a myofibroblast to create the tension needed to close an open wound. That is the key function of the myofibroblast.
We know that we also have myofibroblasts in our fascia, but what is the reason that we have this? It is not so clear. It is my opinion that, at least in the deeper fascia, they probably are stiffening around a problem. Unhealthy fascia will have many myofibroblasts. When the environment has a problem, probably the fibroblasts are triggered to become myofibroblasts and that creates a reinforcing loop. After a problem starts in a local tissue environment, the myofibroblasts begin to work in the extracellular matrix creating tension, then more and more fibroblasts will then get recruited to become myofibroblasts. It can be a loop of tension around a problem that is reinforcing. This problem in the tissue, then, could get worse and worse. We think this could be a possible mechanism for chronic pain.
In the superficial fascia, I’m not sure whether myofibroblasts are pathological or not, because in the superficial fascia they are probably always present.
LAH: I can imagine that myofibroblasts in the superficial fascia are perhaps monitoring for wounds and ready
CS: Exactly, probably for that reason. Also, from an evolutionary point of view, the superficial fascia derives from the panniculus carnosus1 muscle of animals, so we also have some muscular fibers in the superficial fascia. And probably the superficial fascia has its own tone, which is different from the tone of the underlying muscle. So, the tissue we call fascia can be really different depending on where the connective tissue is located, and we need to understand much more about these differences.
LAH: Do fibroblasts move or migrate? Are they like amoebas with pseudopods that move around?
CS: Yes, they move around, and surely they need some active structures to
LAH: They have a cytoskeleton that changes shape to produce this movement. Do they connect with each other, touching each other to communicate?
CS: They can do that but it is not usually how we find them – fibroblasts are usually independent cells that we find alone. I don’t think they have direct contact, but through the extracellular matrix, they do have some communication at a distance from each other.
LAH: What is a fasciacyte?
CS: Yes, we discovered the fasciacyte (Stecco et al. 2018), between the deep fascia and the muscle (see Figure 5). It produces large amounts of the molecule hyaluronan that facilitates gliding between these two layers. We still need to understand much more about this cell. We saw it for the first time in 2011 during a study about hyaluronan where we had some cells that stained differently than we expected.
It is the kind of cell that we can’t study very well in cadaveric samples because it is easily destroyed in those conditions. Once we understood that, and moved to study the fasciacyte in surgical samples, we learned so much more about it. We found that it was not making collagen fibers, it was not the same shape as fibroblasts, and we found with electron microscopy that it was surrounded by hyaluronan, all around the surface of the fasciacyte. So then when we had this new cell described, we were able to publish our results.
Now I think of fascia as having fibroblasts that produce the fibrotic elements of fascia and transmit the tension with the collagen and elastin fibers. The loose connective tissue permits the gliding. It is there that we find the fasciacytes producing the gliding components of fascia. These different cells have different inputs. These two types of cellular elements work to create the two elements of fascia: structure and glide.
LAH: That is very helpful to hear you describe it like that. When people overdo their activities, like shoveling too much snow or too much weight while working out at the gym, the pain they feel later, is it micro-tears in the fascia?
CS: It can be like this. We can probably have many different types of disruptions in the fascia. We can have thickening, an increase in rigidity, a lack of gliding, a micro-tear, or a change in the components within the fascia. We can have a shift in the number of fibers in the particular fascia. So, we have many ways to disrupt fascia. And only when we understand this can we can do precise interventions. I think that the problem is not really the overload because fascia can tolerate being overloaded well since it is connective tissue and, in general, connective tissue can tolerate being under tension. It is how we generate the overload that is the problem because if the load is done in the proper way, it wouldn’t have become a pain pattern later.
LAH: Interesting, that is something Rolfers think about a lot. You describe that fascia coordinates muscle activity and also acts as a body-wide proprioceptive organ. How do we know that it is a proprioceptive organ?
CS: We have determined this by the type of nerve endings that are inside the fascia, the organization of those nerve endings, and the fact that the fascia is stretched by the muscle in myofascial expansions.2 It is attached to the bone. Every time we move, the fascia is stretched in some specific area, and in that area we have fascial innervation that is like a plexus which creates a network where we can feel this kind of tension – those nerve endings would surely act like a proprioceptive organ. We need more studies to understand this better, it is not easy to isolate functional fascia.
LAH: Right, those types of study would have to be in vivo.
CS: Yes, and also the fascia is totally connected with many different elements, so we have to start at the beginning by isolating the function of one particular element. This is not so easy.
LAH: You already mentioned that there is autonomic innervation in the fascia, what other kinds of innervation can be found in fascia?
CS: There is sensory innervation and autonomic innervation. The proportion of these two types of innervation changes with different types of fascia. For example, the muscular fascia has much more sensory innervation and less autonomic, but still around 30% of innervation there is autonomic. In the superficial fascia, it is almost the contrary, so we have much more autonomic innervation and less sensory, and that is interesting because it is not what I expected. The superficial fascia is just under the skin, so I expected more sensory nerve fibers because we can feel so much from below our skin. But I was surprised to find a huge amount of autonomic fibers in the superficial fascia layers, so this means that it probably regulates vascularization, lymphatic drainage, thermoregulation, and many factors related to autonomic input. Also, it probably is a collection of input from the outside to our body that is totally unconscious. That is probably one of the key roles of superficial fascia.
LAH: Dr. Stecco, thank you so much for your time today and your insights about fascia. You’ve given us a lot to think about and I’d encourage our readers to study your research. It takes our knowledge about fascia to new levels.
CS: You are welcome. It was a real pleasure to talk with you.
1. “Panniculus carnosus is a thin striated muscular layer intimately attached to the skin and fascia of most mammals, where it provides skin twitching and contraction functions. In humans, the panniculus carnosus is conserved at sparse anatomical locations with high interindividual variability, and it is considered of no functional significance (most possibly being a remnant of evolution)” (Naldaiz-Gastesi et al. 2018, 275).
2. Myofascial expansions are places in the body where the dense connective tissue within the muscle is connecting to fascia, and they have their collagen fibers parallel to each other. For example, the lacertus fibrosus is the expansion of the biceps brachii fascia that is continuous with the medial region of the antebrachial fascia (Stecco 2015).
Dr. Carla Stecco is an orthopedic surgeon and professor of human anatomy and movement sciences at the University of Padova, Italy. She is a founding member of the Fascial Manipulation Association and of the Fascia Research Society. Her scientific activity is devoted to the study of the anatomy of human fasciae from a macroscopic, histological, and physio-pathological point of view. She has personally done over a hundred human cadaver dissections for research. She is the author of several books and more than a hundred and eighty peer-reviewed articles.
Lina Amy Hack, BS, BA, SEP, became a Rolfer® in 2004 and is now a Certified Advanced Rolfer (2016) practicing in Canada. She has an honors biochemistry degree from Simon Fraser University (2000) and a high-honors psychology degree from the University of Saskatchewan (2013), as well as a Somatic Experiencing® Practitioner (2015) certification. Hack is the Editor-in-Chief of Structure, Function, Integration.
Adstrum, Sue, Gil Hedley, Robert Schleip, Carla Stecco, and Can A. Yucesoy. 2017. Defining the fascial system. Journal of Bodywork and Movement Therapies 21:173-177.
Dawidowicz, Joanna, Natalia Matysiak, Sylwia Szotek, and Krzysztof Maksymowicz. 2016. Telocytes of fascial structures. In Wang, X., and D. Cretoiu (eds) Telocytes.
Advances in Experimental Medicine and Biology, vol 913. Springer, Singapore: 403-424.
Naldaiz-Gastesi, Neia, Ola A. Bahri, Adolfo López de Munain, Karl J. A. McCullagh, and Ander Izeta. 2018. The panniculus carnosus muscle: An evolutionary enigma at the intersection of distinct research fields. Journal of Anatomy 233(3):275-288.
Stecco, Carla, A. Porzionato, V. Macchi, C. Tiengo, A. Parenti, R. Aldegheri, V. Delmas, R. De Caro. 2006. A histological study of the deep fascia of the upper limb. Italian Journal of Anatomy and Embryology 111(2):105-110.
Stecco, Carla, O. Gagey, A. Belloni, A. Pozzuoli, A. Porzionato, V. Macchi, R. Aldegheri, R. De Caro, and V. Delmas. 2007. Anatomy of the deep fascia of the upper limb. Second part: Study of innervation Morphologie 91(292):38-43.
Stecco, Carla, Marco Corradin, Veronica Macchi, Aldo Morra, Andrea Porzionato, Carlo Biz, and Raffaele De Caro. 2013. Plantar fascia anatomy and its relationship with Achilles tendon and paratenon.Journal of Anatomy 223(6):665-676.
Stecco, Carla. 2015. Functional atlas of the human fascial system. New York: Churchill Livingstone Elsevier.
Stecco, Carla, and Robert Schleip. 2016. A fascia and the fascial system. Journal of Bodywork and Movement Therapies 20:139-140.
Stecco, Carla, Caterina Fede, Veronica Macchi, Andrea Porzionato, Lucia Petrelli, Carlo Biz, Robert Stern, and Raffaele De Caro. 2018. The fasciacytes: A new cell devoted to fascial gliding regulation. Clinical Anatomy 31(5):667-676.
fascia; fascial system; cadaver dissection; non-specific pain; fascia innervation; fascia research; superficial fascia; deep fascia; fibroblast; myofibroblast; fasciacyte. ■
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