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Partners in Crime: The Illio-Psoas

The Psoas (so-as) is a unique muscle in the body in that it is the only muscle that

connects the spine with the legs, and it's also a hip flexor. It's a bit of a brute of a muscle that is frequently the source of low back pain, hip pain, and even neck pain. The Illiacus is an independent muscle from the Psoas, but they both attach/insert at the same tendon. The Psoas by far takes more heat and blame as the cause of pain, and as a result gets far more attention in treatment, but the Illiacus can remain a culprit even after Psoas issues are resolved, so it's important to assess, and if necessary, treat both.

Some Basic Anatomy

The Psoas Major attaches to the T12-L4 vertebral bodies and the L1-L5 transverse processes at its origin. Its primary role is as a hip flexor, but it also plays a role in sidebending the spine. In individuals who have a Psoas Minor, this muscle usually attaches to the T12-L1 vertebral bodies at its origin and inserts at the iliac fascia bilaterally. The Psoas Minor muscle assists the psoas major in both hip and lumbar spine flexion. The lower portion of the Psoas Major combines with fibres from the Iliacus muscle, which lies inside the inner surface of the Illium (your hip bones) and Sacrum (your tailbone), to become the Iliopsoas muscle as it curves over the pubic bone and inserts on the lesser trochanter of the Femur.

The Great Pretender

It's easy to see how anything amiss with this dynamic duo can wreck havoc with the low back and hips, and is a common cause of low back, neck, and hip pain. In Psoas Sydnrome, certain symptoms are common, including pain in the lumbosacral region when sitting or standing, delay or difficulty in achieving a fully erect posture, and pain in the contralateral (opposite) glutes. It's earned it's title The Great Pretender, because it can mimic many other physical issues, and as a result be over looked as a diagnosis: Due to it's diverse fascial (a type of connective tissue) connections, it can influence the functioning of the diaphragm, and visa versa, among many other areas of the body. It has been postulated that persistent spasm of the psoas muscle is responsible for more disability than pathologic conditions of other back muscles. (1)

If a patient with a psoas muscle spasm is left untreated, the body attempts to compensate for the change in structure, potentially causing several additional somatic dysfunctions that lead to additional symptoms. (1) This can include rotated lumbar and sacral vertebrae, rotated pelvis, leg length discrepancy, hyper-lordosis (a sway back), disc problems, scoliosis, hip degeneration, knee pain, anxiety, menstruation pain, digestive issues and Sciatic pain due to Piriformis compression (see my previous post on Piriformis Syndrome). Irritation to the sciatic nerve in patients with psoas syndrome often causes pain that radiates down the back of the (opposite) leg and stops at the knee. (2)

The Illio-Psoas and Stress

The Lumbar Nerve Plexus, is a group of autonomic nerve ganglia which innervates the viscera below the diaphragm, is embedded in the Psoas.

In response to threat (Fight or Flight), the psoas will constrict. If stress is continual, along with other effects throughout the body, the psoas can have a significant impact on the ability of the viscera to function optimally, as well as the negative effects that this has on the stability of the back. Given this, Stress is a significant contributor to Psoas tension and it's related back pain and other symptoms. These patterns can become habitual and create numerous issues with posture that effect circulation - all of this in the end contributes to a negative and diminished sense of wellbeing. Of course, any history of injury, no matter how "minor", can never be overlooked because the source of pain is often not where pain is experienced. See the chart below to see how compression in the Lumbar Plexus nerves can refer pain elsewhere in the body.


Sitting for long periods of time, including driving, when the legs are flexed causes tight hip flexors and weak glutes. Runners, because of the extensive use of their hip flexors, often experience Psoas related issues. The tightened psoas pulls the lower spine forward and the lower back muscles tightening to counter this pull. It's common for the Psoas to be tighter on one side than the other, which then creates a torsion in the spine. This will compress the facet joints and intervertebral discs of the lumbar spine, which causes irritation and pain. Over time this situation may lead to more serious structural problems, which is one of the reasons that sitting is now seen as the new smoking.

Much Ado about Something

The goal here is to relax, release, and lengthen a tight and cranky Illio-Psoas as well as to treat and address any contributing and compensatory patterns. In Osteopathy we conduct a thorough assessment and history, including injury evaluation, to pinpoint the root cause of not only the pain, but of other contributing factors. This can include assessing apparently "unrelated" areas such as the diaphragm, intercostal muscles and/or oblique muscles which can play a significant role not just in back pain, but in causing the Illio-psoas to be hyper or hypoactive. Once identified, we will recommend a treatment plan specific for you, and to help you regain strength, stability and balance.

Specific osteopathic techniques including Craniosacral therapy, Visceral Manipulation, Mobilizations, and homework. Stretching is important, but stretching without first releasing the Illio-Psoas can, in and of itself, cause problems, so it's important to have the appropriate assessment and treatment before embarking upon strengthening and stretching exercises. As these are paired muscles that are also bilateral, it's key to determine how each side is effected, and why. Heading straight for the stretch can actually cause further instability. Ironically, a simple technique that engages contraction prior to stretching (Muscle Energy Technique) can be the most effective approach.

Truth be told, releasing the Psoas doesn't initially earn me any friends; it can be rather unpleasant. But a good therapist always relies on both verbal feedback and observation, and a few moments of discomfort is worth the resulting freedom from pain.

There's a good reason Psoas (so-as) sounds a lot like sore...well, you know. Because it sure can be!

Illio-Psoas syndrome and dysfunction doesn't have to remain a pain in the butt,

however. Butt now I'm just being cheeky.

Puns completely intended!


1. Diagnosis and manipulative treatment: thoracic region. In: Kuchera WA, Kuchera ML. Osteopathic Principles in Practice. 2nd ed. Columbus, OH: Greyden Press; 1994:480-488.

2. Kuchera WA. Lumbar region. In: Ward RC, ed. Foundations for Osteopathic Medicine. 2nd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2003:747-748.

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