In this series, I share a complex per post. Starting with the sagittal big toe, working my way up to the sagittal thumb, before doing the same with the complexes of the frontal (aka, coronal) and transverse (aka, horizontal) planes, respectively. The first post in the series explains single- and multi-complex muscles, introduces complexes as I use them in Anatomy by Planes, and explains why complexes make it easier and more effective to resolve pain complaints through treatment and exercise. Enjoy!
A complex is a cluster of interconnected skin, joints, and muscles grouped by a plane-specific motion they share: flexion-extension, abduction-adduction, or lateral-medial rotation.
As massage, soft-tissue, and movement therapists, we help our clients muscle by muscle and joint by joint. It's how we were taught, and for most of us it's how we work.
In this series, I suggest you can, in addition to that, treat and exercise your clients complex by complex. It's a small shift from your usual practice with profoundly better outcomes. Here's what I mean.
A new client, a professional soccer player, presents with recurrent ankle sprains. They've rolled it three times in the last year and visited several different therapists. They point to the outside of the ankle and tell you it hurts with inversion and dorsiflexion, although not as much.
With a muscle-by-muscle and joint-by-joint approach, you start with the basics: the lateral collateral ligaments of the ankle, the peroneal muscles that protect them, the joint capsules, etc. You palpate for tightness or tenderness, treat what you find, and send them home with strengthening exercises for the muscles you worked on. A few weeks later, they're back with the same complaint.
It’s exactly what happened prior to visiting you.
With a complex-by-complex approach, how you treat is motion-driven. The client has already pointed you in the right direction: inversion of the frontal ankle and dorsiflexion of the sagittal ankle. These motions identify the complexes. You start with the frontal ankle, it is an inversion trauma, after all: you now know which skin, joints, and muscles to evaluate and treat as one unit—not just the lateral collateral ligaments and peroneals, but all the parts that make inversion-eversion happen.
To accelerate healing and prevent recurrence, the framework automatically gives you the next moves. The frontal big toe, frontal knee, and frontal hip are reciprocally related to the frontal ankle. Your initial screening also pointed to the sagittal ankle—remember, dorsiflexion was uncomfortable. So, if necessary, you also evaluate the sagittal big toe, sagittal ankle, and sagittal knee. You evaluate, quantify, treat, and exercise all — and often that's where the unresolved pieces are hiding. The muscle-by-muscle approach has no equivalent map; you're left guessing.
Resolving pain and dysfunction should not be a guessing game. The motion-based, complex-by-complex approach is developed to not miss anything important without having to screen the entire body.
That's the shift. The rest of this post explains what a complex is, why working complex by complex makes sense anatomically, and how the approach plays out clinically.
The Body, Pain, Dysfunction, and Our Work Are Holistic
All of us were taught traditional dissection-based anatomy. And for good reason. It provides details on skin, individual muscles, joints, nerves, and more, and helps us understand their individual architecture, location, and isolated function. It gives us an idea of what we're working with.
Although useful beyond a doubt, dissection-based anatomy covers only part of what massage, soft-tissue, and movement therapists need to do their jobs.
Because the body, pain [1], and dysfunction [2] are holistic, we also require knowledge of anatomical interconnections and their consequential reciprocal relationships, which traditional dissection anatomy does not teach.
You and I both know that everything connects; we understand the body is one whole—at least in concept. Muscles connect with bones, bones connect with other bones, skin connects with nerves, nerves connect with muscles, and so on and so forth. Although the concept of interconnections makes sense, working with it in your practice and clinic is not easy. There are so many connections, it’s confusing and overwhelming. With a muscle-by-muscle mindset, this is amplified - the saying “not seeing the forest for the trees” comes to mind.
Anatomy by Planes makes interconnectivity actionable. It does so through complexes.
Intra-complex and Inter-complex Reciprocal Relationships
As mentioned previously, a complex is a cluster of interconnected parts of the integumentary, skeletal, and muscular systems grouped by a plane-specific motion they share: flexion-extension, abduction-adduction, or lateral-medial rotation.
Because they interconnect, the skin, joints, and muscles that make up a complex have intra-complex reciprocal relationships. That means that a change in one part of a complex results in a change in another part of the same complex. For better or for worse.
For example, dysfunctional frontal joints negatively impact the frontal ankle muscles and skin. Just as healthy, fully functional frontal ankle muscles and skin have a positive effect on the frontal ankle joints.
The body consists of nineteen of these complexes, from the big toe to the fingers. Eighteen complexes move in the sagittal (flexion-extension) plane; fourteen move in the frontal (abduction-adduction) and transverse (lateral-medial rotation) planes. For a list see blog post, A Complex.
Because adjacent complexes share parts of the integumentary, skeletal, muscular, and all other organ systems, they (i.e., complexes) also have inter-complex reciprocal relationships. This is true within the same plane (intra-plane) and between planes (inter-plane). [2]
It means that the frontal big toe, frontal knee, and frontal hip affect the frontal ankle. And that the sagittal ankle changes the frontal ankle.
Please note that the transfer of influence through intra- and inter-complex reciprocal relationships is either neutral, positive, or negative.
So, how does all of this help you clinically?
Treating Complex by Complex
Because I reorganized human anatomy by the anatomical planes of motion, you can use flexion-extension, abduction-adduction, and lateral-medial rotation to evaluate, quantify, treat, and exercise.
In Anatomy by Planes, motion is the common denominator of every organ system and all its parts. And like in maths, because it is, motion “leads the way.”
In contrast, the common denominators of traditional dissection anatomy are, among others, a regional approach and “cutting apart.” Both are the very opposite of holistic.
Clinically, based on which motion is affected most, is most painful or dysfunctional, you pick a complex. From here, you evaluate, quantify, treat, and exercise the skin, joints, and muscles that are part of the complex you picked. If necessary, you cast a wider net by screening reciprocally related intra-plane or inter-plane complexes. The atlas and clinical guide show which complexes connect; they show reciprocal inter-complex relationships.
Treatment and exercise bring the therapeutic variables of the integumentary, skeletal, and muscular systems to a healthy, functional range. This helps the body resolve pain and dysfunction.
The complex-by-complex approach still works even when painful or dysfunctional motions span multiple planes and don't fit cleanly into one. The reason is that organ systems overlap significantly across adjacent complexes and across planes — there's both intra- and inter-complex overlap, and intra- and inter-plane overlap. This redundancy is how the body maintains function when something is damaged or impaired, and as therapists we can use it to our advantage.
An Example: The Frontal Ankle
The images below are an example of how these posts show a complex.
The first group of images provides an overview: anterior and posterior body, plus the plantar and dorsal foot, which is often overlooked. The parts of the integumentary, skeletal, and muscular systems that belong to the frontal ankle are orange. Orange represents motion; it indicates the skin, joints, and muscles involved in inversion and eversion of the frontal ankle.
The second group shows single-complex muscles compared with multi-complex muscles of the frontal ankle, in eversion and inversion directions.
The third group shows the single-complex evertors compared with the multi-complex evertors of the frontal ankle.
The fourth and last group of images shows the single-complex invertor muscles compared to the multi-complex invertor muscles of the frontal ankle.
Under each image, the skin, bones, joints, and muscles involved are named. For clarity and ease of use, all other organ systems involved are omitted.
Frontal Ankle Complex (eversion-inversion)
Skin, Joints, and Muscles of the Frontal Ankle
ROM (range of motion): 15-50 degrees eversion and 25-70 degrees inversion.
Skin: over the single-complex muscles and dermatomes T11-S2 (paraspinal posterior torso). The range includes both somatic and ANS source segments — the two are integrated at the segmental level. [3, 4]
Joints: subtalar (aka talocalcaneal) and transverse tarsal1 joints (i.e., the calcaneus, cuboid, navicular, and talus and the joint capsules and ligaments that hold them together).
Muscles: extensor digitorum longus, extensor hallucis longus, flexor digitorum longus, flexor hallucis longus, peroneus longus & brevis, peroneus tertius, tibialis anterior, tibialis posterior.
1 The transverse tarsal joint is the talonavicular and calcaneocuboid joints combined.
Single-Complex Muscles vs Multi-Complex Muscles
Single-Complex Muscles: peroneus longus & brevis, peroneus tertius, tibialis anterior, tibialis posterior.
Multi-Complex Muscles: extensor digitorum longus, extensor hallucis longus, flexor digitorum longus, flexor hallucis longus.
Single-Complex Evertor Muscles vs Multi-Complex Evertor Muscles
Single-Complex Evertors: peroneus longus & brevis, peroneus tertius.
Multi-Complex Evertors: extensor digitorum longus.
Single-Complex Invertor Muscles vs Multi-Complex Invertor Muscles
Single-Complex Invertors: tibialis anterior, tibialis posterior.
Multi-Complex Invertors: extensor hallucis longus, flexor digitorum longus, flexor hallucis longus.
About Single- and Multi-Complex Muscles
Single-complex muscles and multi-complex muscles are, in a way, similar to what's known as monoarticular and polyarticular muscles.
The standard definition for monoarticular muscles is: muscles that cross one joint, while polyarticular muscles cross two or more joints. The main function of monoarticular muscles is to act as a "prime mover," and polyarticular muscles control and coordinate motion.
While making the atlas, I noticed that the terms monoarticular and polyarticular, as applied to muscles, are inherently flawed. I found that monoarticular muscles, more often than not, cross multiple articulations.
The vastus lateralis, for example, crosses the tibiofemoral (two distinct articulations - there’s no agreement among scientists) and patellofemoral joints - the joints of the sagittal knee. Because it does, it cannot be considered monoarticular. Especially in regard to our work. We cannot overlook the different bones and their articulations influenced by each muscle. Regarding the standard terms used, most muscles considered monoarticular are in fact polyarticular. Still, their function as potential prime movers remained.
My solution was replacing the terms monoarticular and polyarticular with single-complex and multi-complex. After all, most complex joints, like the sagittal knee, frontal ankle, and transverse thoracic, move as one anyway.
So, “single-complex muscle” refers to a muscle that moves one complex only, while a “multi-complex muscle” moves two or more complexes. Still, single-complex muscles are generally considered prime movers. Just like multi-complex muscles are believed to be more involved in the control and coordination of motion.
References
[1] Raja SN, Carr DB, Cohen M, Finnerup NB, Flor H, Gibson S, Keefe FJ, Mogil JS, Ringkamp M, Sluka KA, Song XJ, Stevens B, Sullivan MD, Tutelman PR, Ushida T, Vader K. The revised International Association for the Study of Pain definition of pain: concepts, challenges, and compromises. Pain. 2020;161(9):1976–1982. [doi: 10.1097/j.pain.0000000000001939]
[2] Sueki DG, Cleland JA, Wainner RS. A regional interdependence model of musculoskeletal dysfunction: research, mechanisms, and clinical implications. J Man Manip Ther. 2013;21(2):90–102. [doi: 10.1179/2042618612Y.0000000027]
[3] Bernards ATM. Fysiologie en pathofysiologie van nocisensoriek. In: van Zutphen HCF, van Sambeek HWR, Oostendorp RAB, eds. Nederlands leerboek der fysische therapie in engere zin, Deel I. 4th ed. Utrecht: Wetenschappelijke uitgeverij Bunge; 1991. [WorldCat: title search]
[4] van Cranenburgh B. Segmentale verschijnselen: een bijdrage aan diagnostiek en therapie. 2nd ed. Houten: Bohn Stafleu van Loghum; 2000. [WorldCat: ISBN 9789031343188]
