Whether it’s a running back hurdling a defender and breaking into the open field, a ballet dancer gracefully navigating the stage, or a gentleman strolling down his driveway to get the mail, one thing is abundantly clear: There is no more beautiful combination of art and function than the human movement system. And such beauty and importance naturally drive curiosity.
As humans, we have sought and continue to seek to know more about ourselves and how we operate. The ancient Greeks began dissecting cadavers as their primary means of learning anatomy, and cadaver studies have had a stronghold on our scholastic endeavors ever since.1 However, different cohorts in the movement world have recently called into question the presence and relevance of “dead guy anatomy” and the information that has been ascertained from it.
Debating ‘Dead Guy Anatomy’
“Dead guy anatomy” (I really don’t like that phrase, but that’s what people are calling it) refers to the understanding of movement that developed from studying cadavers. It encompasses the origin, insertion, and subsequent action of a muscle, muscle innervation, fascial lines, tendon stiffness properties, etc. Simply put, it’s everything you learned in your traditional anatomy courses.
The objections to cadaver anatomy certainly have merit and are worthy of discussion. These objections may come packaged in different forms, but they stem from the same premise: We cannot understand how things function by studying them in a nonfunctional state. A fluid-less dead person lying motionless on a steel bed without a functioning nervous system cannot be representative of dynamic human movement. So, while you may yank on rectus femoris and produce knee extension or hip flexion, that’s not what it actually does during the gait cycle. During gait, rectus femoris will act eccentrically to keep the leg from collapsing on itself.
Another take stemming from the aforementioned basic premise is that we are 60% water, and, therefore, our fluid-filled nature has to play a critical role in our movement processes. Our evolutionary origin demonstrates that movement was accomplished by fluid-shifting in an amoeboid fashion to propel us through space, and our current system is just a scaled-up version of that.
Too often, though, critics dismiss cadaver anatomy as a system of levers and pulleys that do not explain how humans actually move and then leave it at that. Some go on to try to explain their more esoteric philosophy, but many just declare “dead guy anatomy sucks” and move on.
An important note here is that some of these more abstract philosophies may, in fact, be fundamentally closer to the truth of human movement or they could be completely bonkers, but regardless, their abstraction makes them less practical and less actionable. That. Is. Dangerous. It leaves coaches and clinicians with no practical framework to operate under. These confused practitioners then go searching for something actionable and stumble upon some guru or absolutist school of thought (probably with some three-letter acronym) and find their haven. Next thing you know, they’re shouting on social media at everyone who doesn’t grind every athlete’s hip into 75 degrees of internal rotation or whatever absurd panacea they’re preaching.
The most disheartening part of this whole process is that cadaver anatomy isn’t wrong; it’s just not always right. Those levers and pulleys do work to produce movement. Tendon stiffness does allow efficient transmission of elastic energy. The origins and insertions of muscles do dictate the possible movements they can produce. The patella does increase mechanical advantage of the quadriceps by increasing the lever arm.Cadaver anatomy isn’t wrong; it’s just not always right… It helps us solve a whole host of problems that our athletes deal with, says @zguiser. Click To Tweet
This stuff matters. It helps us solve a whole host of problems that our athletes deal with. No, it doesn’t solve everything, but models created by humans are not perfect. Furthermore, some of the models that are supposed to replace cadaver anatomy actually just build on top of it. How would we have any idea that rectus femoris acts eccentrically during gait if we did not first understand its origin and insertion through cadaver models?
The Contrarian Problem
I’ll loosely define contrarianism as being different for the sake of being different (or, more likely, for the sake of standing out). Contrarianism is dangerous. It detracts from the essence of well-intentioned, informative, and useful educational materials and undermines said usefulness.
Contrarianism runs rampant through the movement (S&C, PT, fitness, etc.) social media world these days. The vast majority of professionals, whether we admit it or not, absorb a large chunk of our information from social media. Transitively, contrarianism runs rampant through the movement world.
We operate in an unfathomably complex universe, and as human movement experts, our subjects are unfathomably complex human beings with seemingly infinite uniquities; of course, there are situations where an ideology doesn’t work. There are (nearly) no absolutes. I’m not sure if there’s a fundamental misunderstanding of the nature of the scientific method or if it’s just our innate desire to seek simplicity, but we all need to realize and accept that we don’t know what we think we know. Science gives us the most plausible explanation for phenomena based on the evidence available. But both the observed phenomena and the evidence available are continually evolving in many situations, which makes our scientific explanations fluid.Contrarianism vaults “gurus” who tout one-size-fits-all methodologies to the forefront of our industry because they at least provide actionable frameworks and rationales. This is dangerous. Click To Tweet
With such complexity and fluidity, it is inevitable that there will always be a “but” with every model we put out there to explain almost anything. The problem is that we still need real, applicable, and practical frameworks in order to produce fruitful outcomes in our objectives. Contrarianism is actionless. Everything is wrong, so nothing can be done. Contrarianism vaults “gurus” who tout one-size-fits-all methodologies to the forefront of our industry because they at least provide actionable frameworks and rationales. I repeat: This. Is. Dangerous.
Should We Ban Isaac Newton?
Let’s consider some of the most fundamental models that underpin our existence. For the most part, we’re all pretty familiar with Sir Isaac Newton’s work. His three Laws of Motion and his Law of Gravity are probably the most well-known physics concepts ever taught—and for good reason. The concepts behind his work allow us to build bridges, fly planes, and even send people to the moon. Maybe more relevant for us, though, is that he’s allowed us to build better athletes by teaching, well, everything we know about force.
Newton’s laws lay the foundation for our understanding of the universe. Here’s the kicker, though: They’re not always right! Newton’s theory of gravity was wrong about predicting a planet (which would have been named Vulcan) that was supposed to be in the area of Mercury. Without the presence of planet Vulcan, Newtonian physics couldn’t explain Mercury’s wobbly precession. This was the beginning of the unraveling of a previously infallible model.
Physicists then learned that, at high speeds, Newton’s Laws of Motion are increasingly inaccurate. The same goes for Newton’s Laws of Motion with small particles and in strong gravitational fields. The model that we thought governed our universe turned out to be incomplete.
Einstein swept in with the concept of the curvature of space-time (general relativity) and seemingly saved the day. But, that’s not the case. His theory of relativity explains all the really big and really fast stuff, but becomes nonsense when things are taken to the atomic level. Through the work of Niels Bohr, Max Planck, and Einstein, quantum mechanics accurately explained some observations where previous models failed. Quantum mechanics predicts atomic and subatomic concepts beautifully but becomes pure absurdity when applied on a large scale.
Newtonian mechanics, relativity, and quantum mechanics all fall short of explaining the whole picture. But that doesn’t mean physicists have just thrown them away. There’s still work to be done, so physicists understand the strengths and weaknesses of each model and employ them accordingly. If you want to understand black holes, go ahead and pull out the general relativity model. But that doesn’t mean you should go around declaring the death of Newtonian mechanics. Newtonian physics are simple, extremely practical, and accurate for 99.99% of the situations we deal with, just like cadaver anatomy.When you understand where a muscle attaches, you can deduce its action in a variety of kinematic positions, says @zguiser. Click To Tweet
Understanding cadaver anatomy is a foundational component of providing a framework to filter information through when trying to solve a problem. The objections to cadaver anatomy are real, but that should not detract from its usefulness. When you understand where a muscle attaches, you can deduce its action in a variety of kinematic positions.
Consider the piriformis. A tight piriformis is commonly accused of being the culprit responsible for low back, SI joint, and posterior thigh pain. As such, stretching of the piriformis is often prescribed to alleviate these issues. (Whether or not a tight piriformis is actually a common/noteworthy issue and if stretching it will produce meaningful outcomes are both debates for another day. Let’s just assume for this example that stretching the piriformis would be beneficial.) I imagine that if you’re reading this article, you have a specific piriformis stretch that comes to mind—hold onto that thought!
The piriformis originates on the sacrum and sacrotuberous ligament and then inserts into the superior aspect of the greater trochanter. When the thigh is neutral/extended, the piriformis passes posterior to the hip’s axis of rotation in the transverse plane. This makes it a hip external rotator. In order to stretch a muscle, you want to take it directly opposite to the direction of its action. So, in order to stretch the piriformis, we should take it into internal rotation, right? I’m willing to bet that doesn’t match the description of the piriformis stretch you had in mind.
When the hip is flexed to 90 degrees, the piriformis passes anterior to the axis of rotation in the transverse plane and becomes an internal rotator of the hip. The position of the thigh relative to the pelvis completely flips the action of the piriformis. So, as you raise your leg up to put it on top of a box or as you lean your trunk forward, the hip would need to go into external rotation in order to place a stretch on the piriformis.
Understanding the attachment points of the piriformis allows us to not only realize that the piriformis action completely flips based on kinematic positioning, but also allows us to understand how and why that happens. Without a firm understanding of cadaveric anatomy, we wouldn’t have this information. Cadaver anatomy serves as our foundation and allows further deductive reasoning processes to extrapolate to functional situations that take place off of the steel bed.
I’m not saying you shouldn’t question things and seek to have a deeper understanding. In fact, I don’t think you’ll find anyone who promotes an inquisitive nature more than I do. Curiosity is the fuel for progression. You should seek to understand the “why” behind everything that you do. Continual inquisition allows for the development of the most accurate, efficient, and optimal systems possible.
I hope that those who explore other movement strategies continue down their paths and find applications for their methodologies in the same manner that physicists have found applications for general relativity and quantum mechanics. I regard many of those individuals as much smarter than myself, and I have no doubt that their models will bear fruit in time, if they have not already. But that does not diminish the value that is afforded by cadaver anatomy.Present the shortcomings of established models, provide alternatives, but then acknowledge the strengths and utility of the existing models, says @zguiser. Click To Tweet
I simply encourage the manner of questioning and educating to be done in a way that does not entirely undermine the value of proven systems. Present the shortcomings of established models, provide alternatives, but then acknowledge the strengths and utility of the existing models. It’s not hard. It probably won’t get you a lot of followers, but it also won’t feed the flame of confusion and guruism that rages through the movement world.
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1. Ghosh, SK. “Human cadaveric dissection: A historical account from ancient Greece to the modern era.” Anatomy & Cell Biology. 2015;48(3):153-169. doi:10.5115/acb.2015.48.3.153