Fascial Therapy Institute Australia - FTIA

22/10/2026

Everyone Knows the Psoas?

The psoas is a strange name for a muscle, and the silent p probably helps people remember it. Over the past few decades it has moved out of the anatomy texts and into gyms, Pilates studios and sports coaching. Most people who train now know they have one, and many have been told it needs strengthening, stretching or releasing as part of their core.

The idea of the core as we use it today is fairly recent. Hodges and Richardson’s 1996 study found that a deep abdominal muscle, transversus abdominis, switched on later than normal in people with low back pain. A whole generation of core training grew from that finding, and the psoas was swept up with it. Alongside this came a more poetic reputation.

Liz Koch’s The Psoas Book, now in its 2012 thirtieth-anniversary edition, brought the idea of the psoas as a muscle of the soul, holding fear and stress, to many bodyworkers and movement teachers. Eyal Lederman questioned the core story in his 2010 paper “The myth of core stability,” arguing that strengthening the trunk had not been shown to prevent or relieve back pain any better than other forms of exercise.

Everyone knows the psoas. I am less sure we understand it.

My own way into the psoas came from a different direction. In the early 1950s the American osteopath Lawrence Jones had a patient with back pain he had been unable to help for months. The man said his worst problem was that he couldn’t sleep. Jones spent time finding him a position of comfort, folded forward, close to the fetal position, and left him there while he saw another patient. When he came back, the man stood up without pain for the first time in four months. Jones later called it a lucky accident. That night led to his Strain-Counterstrain approach, first published in 1964, and in time to the positional release work I have taught for most of my career.

Folded forward is exactly where a contracted psoas wants to be.
For me, though, the classic psoas story is often more indirect than the direct psoas complaint. The direct complaint is easy enough to show. The Thomas test, an old-school orthopaedic assessment, has the patient lie on their back at the end of the table and hug one knee to the chest. That leg rests in a shortened position. If the psoas on the other side is short, that thigh lifts off the table, and the segment from above the knee to the groin is drawn up. The test is named after Hugh Owen Thomas, who described it in his 1876 work on diseases of the hip. Thomas came from a long line of Welsh bonesetters, so the test has its roots in hands-on work as much as in surgery.

When I was first taught to treat the psoas, and later when I was instructing others, it was approached simply as a muscle. At no time was any information given about the viscera, the organs that lie in front of it. You just pushed down into the psoas with a “no pain, no gain” mindset. This caused a great deal of anxiety, leading to distressing pain for both the receiver and the giver. It left many of us reluctant ever to do it on another client, and some practitioners became afraid to treat the psoas at all. Instruction and direct work have clearly come a long way since then, but that experience has coloured and informed my technique and my teaching ever since.

More often, in my experience, the relationship is a quiet one. I often find a short psoas sitting alongside a shortened TFL (tensor fasciae latae, the small muscle at the front and outer side of the hip that tensions the band running down the outside of the thigh), or alongside gluteal hypertonicity, where the buttock muscles hold more tone than they should. Which is causing which? Sometimes the short psoas seems to be creating the hip discomfort. Sometimes it seems to be the other way around. I can’t prove either, but what matters is understanding that the psoas does not live in isolation. Perhaps working the multifidi, the small deep muscles that run between the vertebrae along the length of the spine, will relax the psoas. Clinically, it often does.
What the anatomy suggests

I don’t claim to have the final word on what the psoas is for. But the researchers who have looked most closely tell a quieter story than the gym or the mythology. Bogduk, Pearcy and Hadfield’s 1992 study found that the psoas has surprisingly little leverage to move the lumbar spine, the five vertebrae of the lower back. Bogduk’s 2005 text describes it instead as an axial compressor. It draws the vertebrae together along the line of the spine, steadying them like a column, rather than bending or twisting them. Its fibres attach to the last thoracic vertebra and to every lumbar vertebra and disc below, with fascial links into the muscles of the spine and pelvis.

That is an elaborate arrangement for a muscle supposedly built only to lift the leg.

Evan Osar takes this further in his 2017 book The Psoas Solution. He argues that the psoas matters less for how much it moves the hip than for how well it holds the hip while it moves. He calls this joint centration: keeping the ball of the thigh bone (the femoral head) centred in its socket (the acetabulum), so the joint surfaces stay in full contact and the load is shared evenly. As the leg lifts, the psoas draws the ball up and in while the lower fibres of gluteus maximus, the large buttock muscle, pull back and down. Between them the joint stays centred. When that control is lost, the ball drifts forward and up, and the front of the hip takes the strain. Osar argues that over time this uneven loading wears the joint.

Seen this way, a psoas that feels tight may be gripping because it cannot do its centring work well. Stretching it harder does not solve that.

The neighbours

And this is where it becomes a bit of a can of worms, because the psoas doesn’t work alone. It lies at the back of the abdomen, and it has neighbours.

The kidneys sit on and beside it. Each kidney rests against the back wall of the abdomen with the psoas along its inner edge, wrapped in its own fascial envelope, the renal fascia, which the Romanian anatomist Dumitru Gerota described in 1895.
The back layer of that envelope blends with the fascia covering the psoas. The ureter, the tube that carries urine from the kidney to the bladder, runs straight down the front of the muscle.
Jean-Pierre Barral observed clinically, in his 2005 work, that when a kidney drops lower than it should (renal ptosis), it slides down along the psoas as if on a rail.

The diaphragm, the dome-shaped breathing muscle, anchors to the front of the upper lumbar vertebrae by two tendon-like legs called the crura. The psoas begins in the same place, passing beneath a fibrous arch of the diaphragm called the medial arcuate ligament. Barral also observed that the left psoas is often in spasm in people with gastro-oesophageal problems such as reflux, which he linked to this shared anchorage.

The bowel lies in front of it too. The mesentery, the fan of tissue that suspends the small intestine from the back wall of the abdomen, has its root running diagonally across the front of the lower spine and over the right psoas. The ascending and descending colon sit close in front of the psoas on either side, and the greater omentum, the fatty apron that hangs from the stomach over the intestines, is attached to the colon above. Perhaps the colon and small intestine, through the mesentery or the greater omentum, are the culprits.

Then there are the nerves. The lumbar plexus, the network of nerves supplying the lower abdomen, the groin and the front and inner thigh, forms inside the psoas itself. Its branches leave through the outer edge of the muscle, through the inner edge, and in one case straight through the front of it.

The femoral nerve, which supplies the quadriceps at the front of the thigh, continues in the groove between the psoas and iliacus, the fan-shaped muscle lining the inside of the pelvis. Along the inner border of the psoas runs the sympathetic chain, the string of nerve clusters that governs our automatic stress responses.
That is an interesting neighbour for a muscle with this reputation, though it tells us the two live close together, not that one controls the other.

Why this matters for the way we work

If the kidney cannot glide, or the diaphragm is held, the psoas may be guarding on their behalf. If nerves pass through a muscle that is gripping, they may not slide as they should. David Butler’s 1991 Mobilisation of the Nervous System made the case that nerves need room to move with the body, and that an irritated nerve can produce pain well away from where the trouble lies.
Organs and nerves also respond poorly to force. Deep, insistent pressure into the psoas risks aggravating the very structures we are trying to free. This is why visceral and neurofascial approaches belong in psoas work. They let us address the neighbours, not just the muscle.

You can’t see it, you have to feel it

Osar makes a point I agree with: you cannot judge whether a joint is centred by looking at it. You have to feel it. He argues that palpation is our best tool for this, and forty years of hands-on work tells me the same.

One way I assess the psoas is by not palpating it directly at all. Instead I palpate for surface tension in the abdomen, over the path the psoas fibres take beneath it. That line runs from just to the side of the midline below the xiphoid process (the small point at the lower end of the breastbone) down to the inguinal ligament (the band that runs from the front of the hip bone to the p***c bone, at the crease of the groin). If I meet surface resistance along that line, it is at least an indicator of tension on that side, or both sides, that I attribute to a short, contracted psoas.

We never push through that resistance to get at the psoas. In my method we change the compensations and relational structures contributing to the tension, and use that superficial tension as the benchmark for whether something has changed.
The umbilical fulcrum may change it. This is a light finger placement within the umbilicus, the navel, then engaging three planes of ease, following the tissue in the directions it moves most easily: head to foot, side to side and in rotation.

The umbilical fulcrum: light finger placement within the

Working the lumbar and thoracic facets, the small paired joints at the back of each vertebra, at the keystone segments, the junction points of the spine where I find movement is most often held, can change it. Activating the deep front line through low-load Muscle Energy Technique, where the patient contracts gently against my hand, at the phalanges, the small bones of the toes where the deep front line begins with the long toe flexors, will change psoas tone. Palpating and releasing the medial pterygoids, the jaw muscles on the inside of the angle of the jaw, will change psoas tone too.

The rationale is the deep front line. Thomas Myers, in his 2001 Anatomy Trains, described a continuous fascial line running from the inner arch of the foot, up the inner leg, through the psoas and diaphragm, along the front of the spine to the jaw and the base of the skull. With the psoas as the benchmark lens, all of these structures are related tensionally. When one of them changes, I can feel the surface over the psoas change too.

When the surface tension lets go, you are able to press more deeply into the abdominal area and, without much effort, reach the depth of the psoas for palpation. That softness is the benchmark indicator. The psoas itself may have changed, or it may have stayed the same. But a direct application no longer brings on a guarding response in the same way.
That is where "less is more" comes in. I am not trying to overpower a muscle that is already gripping. I am trying to change what it is responding to.

FT5
These are the threads we will follow in FT5 Practical: The Psoas – Deep Front Line, a two-day myofascial visceral masterclass in Ocean Grove on 7–8 November.
References

umbilicus. Photo: Steven Goldstein.

Barral, J.P. (2005). Visceral Manipulation (rev. ed.; originally published 1988). Eastland Press.
Bogduk, N. (2005). Clinical Anatomy of the Lumbar Spine and Sacrum (4th ed.). Elsevier Churchill Livingstone.
Bogduk, N., Pearcy, M. & Hadfield, G. (1992). Anatomy and biomechanics of psoas major. Clinical Biomechanics, 7(2), 109–119.
Butler, D.S. (1991). Mobilisation of the Nervous System. Churchill Livingstone.
Hodges, P.W. & Richardson, C.A. (1996). Inefficient muscular stabilization of the lumbar spine associated with low back pain: a motor control evaluation of transversus abdominis. Spine, 21(22), 2640–2650.
Jones, L.H. (1981). Strain and Counterstrain. American Academy of Osteopathy.
Koch, L. (2012). The Psoas Book (30th anniversary rev. ed.). Guinea Pig Publications.
Lederman, E. (2010). The myth of core stability. Journal of Bodywork and Movement Therapies, 14(1), 84–98.
Myers, T.W. (2001). Anatomy Trains: Myofascial Meridians for Manual and Movement Therapists. Churchill Livingstone.
Osar, E. (2017). The Psoas Solution. North Atlantic Books.
Standring, S. (ed.) (2021). Gray’s Anatomy: The Anatomical Basis of Clinical Practice (42nd ed.). Elsevier.
Thomas, H.O. (1876). Diseases of the Hip, Knee, and Ankle Joints, with Their Deformities, Treated by a New and Efficient Method (pp. 16–26). Liverpool: T. Dobb

21/10/2026

My second webinar will be FT10 Biofields Therapy to be held on Sunday November 29th, 2026 4-7pm
Live is $99. Replay is $55. Both stream through You Tube.

https://www.trybooking.com/DQZWQ

This eclectic webinar is an exploration from what is known to what is unknown.

The term “biofield” was coined in 1994 by a panel convened by the US National Institutes of Health’s Office of Alternative Medicine. It has since been treated as an emerging field of research.

We will take a broad swath through subtler hands-on work and then consider what occurs when the hands are removed.
We consider the rich history of hands on healing from biblical to contemporary.

We consider the dimension of a what I consider a soul based approach.

We look at holism and reductionism, and at what “energy medicine” actually means.

We consider advocates such as James Oschman, whose 2000 book Energy Medicine: The Scientific Basis set out many of the concepts and models we’ll discuss. We look at spiritual traditions through history that practised hands-on healing, and what that meant to them.

We then turn to contemporary views of the biofield, including those who have courted controversy, such as Rupert Sheldrake and his 1981 hypothesis of morphic resonance (the idea that living systems inherit a kind of collective memory from others of their kind).

From there we move into exercises to sense energetic exchange between yourself and a partner, and then apply this to living, vibrant soft tissue and bone. We explore this interface. We consider the work of the late Fritz Smith, whose Zero Balancing (developed in the early 1970s) focuses on the energy held in bone, and we use tuning forks to resonate into bone.
The fundamentals of safety (grounding, presence and intention) are explored, with strategies to bring them into your practice. We also look at a range of concepts and applications, including fulcrums (points of held pressure or stretch that the body organises itself around), the auric field, chakras, and the use of pendulums as a diagnostic tool.

This is a comprehensive look at the various proposed mechanisms, and at how difficult this work is to advocate to a mainstream or skeptical audience.

This eclectic webinar is an exploration from what is known to what is unknown. The term “biofield” was coined in 1994 by a panel convened by the US N

04/09/2026

In the next few weeks I'll be starting my new Fascial Therapy Webinar series that I had run with my esteemed colleague Craig Smith at Club Physio which we called Core Connections, whose untimely passing in January, has many of us still grieving him.

This is a new process for me as I'm going to use Riverside as my platform. If your interested in any of my webinars could you please PM me and let me know and privately if you wish leave your email address, so that I can compile an up to date database for those interested.

Initially there will be a live and replay availability, with differing price structure once I figure out how all this will work.
As always thank you for all your support through the years.

30/08/2026

The Words We Haven't Found Yet:
Fascia, Evidence, and What Happens Under My Hands

I want to describe something I do most weeks before I say anything else about research or philosophy, because it is where this whole piece actually starts for me.

A client lies on their side. I hold the knee and the ankle and roll the leg slowly forward and back, searching for the position where the hip finds its own greatest ease. When I find it, I stop, simply hold, and continue to track and perceive stillness or motion through my felt sense. And yet the whole hip, knee and ankle complex begins to change under my hands — softens, deloads, settles into something different than what I started with.

Sometimes I feel pulsation. Sometimes fuzziness. Sometimes absence, especially when palpating the tibia or femur itself, at the condyles or along the shaft. Sometimes the bone feels icy cold. All of this is a daily occurrence. None of it is out of the ordinary, and yet it is, isn’t it? What I feel is often called illusion, or pareidolia — the mind finding a pattern where none exists. To me it is not imaginary. It is real.

People often cannot find words for what they feel while this is happening. They describe warmth, or a sense of flow, or simply say they don’t know how to explain it. Something shifts. I did not manufacture that shift. I positioned the tissue and waited, and the change arrived on its own terms.

This happens often enough, and predictably enough, that I trust it. What I have never been comfortable with is the next question clients sometimes bring me: they want that shift to be an emotional release, specifically — they arrive believing their fascia is holding a trauma, and they want me to release it. I have to tell them that is not how it works. I cannot conjure an emotional release. When one happens, it is authentic and spontaneous, and it announces itself in the body, not in a story I supply: a change in breathing, rapid eye movement, a fasciculation, a pulse you can suddenly feel at the carotid, a sudomotor response — the skin's own involuntary reaction. Those are autonomic phenomena, arising from a real state change in the tissue. They are not something I produce on request, and I will not pretend to a client that I can.

What the Research Has Been Confirming

I have spent this year reading two very different bodies of writing that, without knowing it, have been confirming what my hands already told me.

One is a live argument between anatomists. In 2026, Neumann and colleagues published a paper in Clinical Anatomy defending a strict, traditional definition of fascia — fibrous membranous sheets, classifiable within the body's existing anatomical systems. Nemetz, Stecco, Schleip and colleagues replied that this cannot hold, because fascia behaves as a continuous, body-wide network that resists the clean boundaries dissection has always imposed on it. I recognise both sides of that argument in my own hands. What I feel under the knee and ankle is never an isolated sheet. It is continuous with everything around it, and it changes as a whole.

The other is a run of careful writing correcting how practitioners explain what touch does. Mechanotransduction — real, established biology describing how cells respond to mechanical cues — keeps getting stretched into claims about tissue repair the cell studies never demonstrated. Neuroplasticity, the nervous system's ordinary capacity to adapt, keeps getting inflated from “the brain changes in response to touch” into “massage rewires the brain.” And the felt sense of a fascial release keeps getting treated as proof that tissue itself has changed, when the more honest reading is that something changed in what the person felt — which is real, and matters, and is not the same claim.

I recognise this correction too, because it is the same discipline I already practise with clients who want an emotional release I cannot supply. Don’t claim the mechanism. Describe what you actually observed.

A third voice pushes further still. John Sharkey, in a 2026 paper titled Fascia Is Not a System, argues that fascia fails to meet the formal anatomical criteria for a system at all — not because it is fragmented, but because it is a continuum that underlies the very idea of separate systems in the first place. Development, on this reading, does not begin with the cardiovascular system and the nervous system as distinct entities that fascia later connects. It begins with continuity, out of which those systems are later described and named. Sharkey's argument is the most radical of the three, and it is the one that comes closest to what I feel with my hands: not a system among systems, but the ground the systems were carved out of.

What Recovery Taught Me About Not Knowing

In June this year I was hospitalised and became, for a while, as weak as a kitten. Recovering from that, I noticed something in myself I still cannot fully account for: a deepening of perception.

A sense — I use that word carefully — that surviving something extreme had triggered some kind of energetic recalibration.
I do not know if that is true. It may be exactly what it sounds like. It may also be a story I have built to make sense of a mind that, after serious illness, simply had the noise stripped out of it and started noticing what was already there to be noticed. I hold both of those possibilities at once, and I have decided I do not need to resolve which one is correct in order to trust what I am now doing with my hands. That not-knowing, held without needing to force an answer, is itself the thing I want this piece to be about.

I will admit something else here, because this piece has asked everyone else to be honest about their claims and it would be a poor argument if it were not equally honest about mine. I notice a pull in myself toward frameworks that would settle this more comfortably than it wants to be settled — toward language borrowed from physics, toward theories of subtle fields and energetic memory that promise a mechanism waiting behind what I feel under my hands. That pull is not always led by evidence. It is led by something in me that wants the felt sense of threshold to have an explanation available to it. I do not think the honest response is to suppress that pull, and I do not think the honest response is to indulge it as though it were established. The honest response is to notice it, name it here, and keep holding it apart from what I can actually claim to know.

It is easy to read the recovery story as a digression from the anatomists and the evidence-writers. I don’t think it is one. They are all practising the same discipline from different directions — staying with what is actually observed, resisting the pull to close the gap with a story that feels satisfying but outruns the evidence. Mine happens to be a story about my own hands and my own recovery rather than about a cell culture or a cadaver. The discipline required is identical.

Language for What I Already Do

Maurice Merleau-Ponty gives me language for something I have felt at the table for decades without a name for it: the difference between the corps objectif, the body as object — the body of dissection, of Neumann's careful definitions — and the corps vécu, the lived body, the body a person actually inhabits and feels from the inside. When I hold that hip in stillness and wait, I am not acting on an object. Touch, Merleau-Ponty noticed, is always double: the hand that senses is, in the same moment, aware of itself sensing. That doubling is exactly what a client is registering when they cannot find the words for what is happening — they are not confused. They are accurately describing something mechanistic vocabulary was never built to hold.

Henri Bortoft's distinction between a counterfeit whole — reassembled afterward from its parts, which is really just the parts wearing a disguise — and an authentic whole, present from the start and never built by addition, describes precisely why I cannot treat the hip, the knee and the ankle as three things I am separately adjusting. What changes under my hands changes as one thing, or it does not really change at all.

Martin Buber's distinction between I-It and I-Thou gives me the cleanest account yet of the line I already draw with clients who want a manufactured release. I-It is the register of assessing and using — necessary, and most of clinical language lives there. I-Thou is the register of meeting rather than knowing about: something arising between two people that belongs to neither one alone, and cannot be produced to order. That is exactly why I tell clients I cannot conjure their release. It was never mine to produce.

The Words We Are Still Looking For.

None of this settles the vocabulary question, and I am wary of anyone — myself included — who proposes a tidy replacement and calls it finished. I am part of an ongoing effort among colleagues to find language for fascia and touch that does not default to mechanism — words that hold the felt, lived experience of a session without either overclaiming a hidden mechanism or dismissing what clients report simply because it resists measurement. We have not landed on that vocabulary yet. I am not sure a single vocabulary is even the right goal. What feels more honest is testing candidate words against what actually happens at the table, the way I have had to test “release”, “threshold” and “acceptance” against decades of hands-on experience before I trusted any of them.

What I can offer with confidence is this: the softening I feel under my hands is real. The fact that neither I nor the current research can fully explain why does not make it less real — it makes the explaining a separate, ongoing piece of work from the doing. My recovery this year taught me to hold that gap without needing to close it prematurely. That, I think, is what acceptance actually means in this work — not passivity, but the discipline of staying present to what is happening without insisting it have meaning, or any comprehensible rationale, before it makes sense to that person's own experience.

Steven Goldstein
Director, Fascial Therapy Institute Australia
fascialrelease.com

24/08/2026

FT5 The Psoas — Deep Front Line: Diaphragm, Thorax & Pelvis
Two-Day Practical Masterclass with Steven Goldstein | October 24–25, 2026 | Ocean Grove, Victoria

The psoas isn't just a hip flexor. It's the muscle that runs from the last rib and lumbar spine down through the pelvis to the top of the femur (thigh bone) — and increasingly, it's understood as a relational structure, wired into breathing, the viscera and the nervous system, not an isolated mover.

In this two-day practical masterclass, join Steven Goldstein to explore the psoas through the lens of the Deep Front Line — the body's deepest myofascial (muscle-and-connective-tissue) pathway — and its relationship to the diaphragm, thorax and pelvis. Drawing on Liz Koch's work on the psoas as the body's "messenger," alongside osteopathic and visceral manual therapy approaches, this course blends clear biomechanical technique with a fuller, embodied view of this remarkable muscle.

Over two days you'll:
● Build core Fascial Therapy skills — ease and bind assessment (finding the direction tissue moves most freely, to guide treatment) and tensegrity-based technique
● Trace the Deep Front Line from foot to jaw, with hands-on work at key stations along the way
● Explore the diaphragm–psoas–viscera relationship, including how breathing mechanics influence psoas tone
● Practice visceral techniques for the colon and abdominal viscera, including rebound/recoil and Toldt's fascia release
● Learn practical assessment tools — Thomas Test variations, joint centration, and reactive muscle relationships from TMJ to pelvis
● Consider the somato-emotional dimension of psoas holding patterns and diaphragmatic breathing

Suitable for remedial massage therapists, myotherapists, osteopaths and physiotherapists wanting a deeper, more relational approach to core and pelvic work.

📍 Ocean Grove, Victoria 📅 October 24–25, 2026 💬 PM me for details

19/08/2026

FASCIAL THERAPY INSTITUTE AUSTRALIA
Sciatica Series — Part 1 of 3

As I ponder and update to my FT2 NFM Neurofascial Mobilisation Masterclass, I pondered cases of sciatica that are tricky at best.
One such is described below. If this interests you to learn more, please PM me and I'm looking at September or October to deliver this masterclass in Ocean Grove, Victoria.

Sciatica That Won't Resolve? Meet the Triple Crush.

Most sciatic pain gets treated as a single problem with a single cause: a disc, a tight piriformis, a pinched nerve root. Sometimes that's exactly what it is. But when the leg pain won't fully settle no matter how precisely you treat that one site, it's worth asking a different question — not “where is the compression?” but “how many compressions?”

What double crush actually means

The double crush concept was first described by Upton and McComas in 1973. Their observation was simple but far-reaching: a nerve that is already mildly irritated at one point along its length becomes far more vulnerable to irritation at a second point further along — even when that second point, on its own, wouldn't normally cause a problem. The nerve is a single continuous structure carrying its own blood supply and axonal transport (the internal system that moves nutrients and proteins along the length of the nerve fibre) the whole way from spinal cord to foot. A mild restriction near the top can lower the nerve's tolerance everywhere below it.

For the sciatic nerve, that means a person can have a mild, almost silent, irritation at the lumbar nerve root (where the nerve exits the spine) that isn't causing much on its own — but which primes the nerve to become symptomatic when it also meets restriction at the piriformis (a deep hip rotator muscle the sciatic nerve passes under or, in some people, through). Neither site alone explains the picture. Together, they do. And with the sciatic nerve, there's a third layer to add — because at some point along its length, it stops being one nerve.

The bifurcation: why this can become a triple crush

The sciatic nerve is really two nerves travelling in a shared sheath: the tibial and common peroneal (fibular) divisions. They usually separate at the apex of the popliteal fossa (the diamond-shaped hollow at the back of the knee), though in a meaningful number of people that split happens much higher — sometimes within the pelvis, occasionally with one division passing through piriformis itself while the other passes beneath it. That variant is worth knowing about on its own, separate from double crush, because it changes what a piriformis-related entrapment can look like.

Once the nerve has split, each branch runs on to its own separate vulnerable point further down the leg. The common peroneal nerve wraps laterally around the neck of the fibula, just below and outside the knee, where it sits close to the surface — the classic fibular tunnel entrapment site. From there it supplies the front and outside of the lower leg and the top of the foot. The tibial nerve continues down the back of the leg and passes through the tarsal tunnel, on the inside of the ankle behind the medial malleolus (the bony bump on the inner ankle), supplying the sole of the foot.

Put those two facts together and a sciatic presentation can genuinely be a triple crush rather than a double one: irritation at the lumbar root, a proximal restriction at piriformis or the bifurcation itself, and a distal entrapment on whichever branch is more involved — fibular head for the peroneal division, tarsal tunnel for the tibial division. Three sites, one continuous nerve, cumulative effect.

Next in this series: once the nerve has split into two branches, where the symptoms show up below the knee becomes a genuine clue to which branch — and which site — needs your attention next.

Reference: Upton, A.R.M. & McComas, A.J. (1973). The double crush in nerve entrapment syndromes. The Lancet.