The Psoas Muscle: Ultimate Guide

August 31, 2021
The Psoas Muscle: Ultimate Guide

Why do we need to know about the psoas muscle?

Questions about the psoas muscle are extremely common, and for good reason. It can be involved in many problems and issues that the general population deals with. Issues with the psoas muscle can be related to lack of core stability, back pain, leg pain, sacroiliac joint (SI joint) pain, breathing problems, and the list goes on. In this article, I’ve put together some important elements to understand surrounding the psoas muscle, and its friend, the iliacus muscle. (I also discuss the psoas in detail in my book Functional Anatomy of Yoga – Get a copy from Amazon if you don’t have it already.)

What do we mean by the word “psoas”?

We use the word psoas most often to refer to the combination of two muscles: iliacus and psoas major muscle. Together these two muscles are better known as the iliopsoas muscle. They are linked together because of their combined attachment to the femur, which we will look closer at later in this article. In this post I’ll refer to the combined muscles as iliopsoas, or simply as the psoas.

There is also another muscle that contains the word psoas and is worth mentioning briefly. It’s called the psoas minor muscle. You can see it on one side of the image below. Psoas minor is on the right side as you are looking at the image. This is the left side anatomically speaking. As it turns out, psoas minor is absent in approximately half of the population. Not to worry, its function is minimal. So, back to the main players.

Iliopsoas Muscle

An overview of the psoas muscle and its friends

The word “psoas”, as I said above, generally refers to the combination of both the iliacus and the psoas major muscles. This is because they link together toward the bottom (distal) end where they attach to the femur. This means that these muscles cross the hip (acetabulofemoral) joint. Because of their position, they are very powerful hip flexors, the strongest in the body in fact. The iliopsoas muscle is probably the single most important postural and structural muscle in the body for the following reasons.


  • Psoas connects the upper half of the body to the lower half of the body.
  • It lies on either side of the sacrum, and therefore our center of gravity, which means…
  • It is a key to controlling big movements of the body.
  • Psoas is related to the strength of the spine.
  • It can create a strong lordosis (accentuated lumbar curve).
  • Psoas can be related to back pain.
  • It is the epitome of our “core” muscles.


  • Psoas lies in the pelvic bowl, which is cross-culturally the origin of energetic circulation.
  • It is related to uddiyana bandha (or are bandhas a myth?).
  • The area that it lies in is also related to emotion, what we sometimes describe as gut instincts, or butterflies in our stomach.
  • It is also related to the fight or flight mechanism. It takes us into a fetal position.

Where is the iliopsoas muscle located?

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The psoas major attaches (originates) proximally (above) on the bodies of the vertebrae, specifically the bodies of vertebrae T12-L4. The bodies of the vertebrae are the large round bony parts that the vertebral disc sits between on the spine. The psoas major attachment is on the sides of this structure.

As the psoas major heads down on either side of the spine it crosses a total of eight joints before heading forward slightly to drop over the front of the pubic bone. It then reaches its distal attachment on the lesser trochanter of the femur. The eight joints that psoas major crosses over are: T12 – L1, L1 – L2, L2 – L3, L3 – L4, L4 – L5, L5 – sacrum, sacroiliac joint, and lastly the hip joint.

Iliacus attaches inside the pelvic bowl onto the inside of the ilium. Specifically, it attaches at the proximal end to the iliac fossa, which is the name for the depression on the inside of the pelvic bowl. The ilium is the large flat bone that sticks up on either side of the pelvis. The attachment of this muscle defies our normal idea of how a muscle attaches to a bone. In the case of iliacus, the tendinous attachment is actually under the muscle itself. It’s not a long round tube of tissue in the way we normally think a tendon is. As iliacus leaves the iliac fossa it joins with the psoas major to attach distally to the lesser trochanter of the femur.

What does the iliopsoas muscle do?

One could easily argue that if a muscle crosses over a joint it can affect that joint. This seems to be true of the psoas major. The psoas major can effect all of the vertebral joints mentioned above. It can either pull the lower ones into a stronger lordotic curve, or if pulling at the top, closer to T12, it can actually reduce the amount of lordotic curve. This depends on other postural issues that are at play.

The iliacus is the lesser known part of the word iliopsoas. The iliacus part of the iliopsoas muscle is dedicated to moving the femur at the hip joint. Short, thick, and powerful, it’s the unsung hero of the iliopsoas story. It creates the powerful hip flexion that we need for so many activities.

Anatomically, the psoas is usually described as doing the actions of flexing the hip joint and externally rotating the femur at the hip. But functionally, the psoas muscle was at a minimum designed to effectively and efficiently put one foot in front of the other, which we know as walking. It does the action of bringing your femur forward by flexing the hip joint. This doesn’t mean that the iliopsoas doesn’t also function in other ways however.

Stabilizes the spine when sitting

Sitting is something that many of us do for many hours in the day. It is a common place where we run into trouble with our psoas muscle. Psoas is active and contracting to a degree (meaning, not the same amount that it would contract if you were running, cycling, or doing a boat pose) when we are sitting. So, this very simple activity has the potential to increase the overall tension in the psoas muscle.

Helps maintain the stability of the SI joint

The relationship of psoas to the sacroiliac joint is also extremely important. Without taking us to a completely new topic, it is the relationship between the psoas and the piriformis muscle that creates a muscular balance most directly at the sacroiliac joint. The ligaments and other postural issues are always part of an SI issue, but muscularly the balance of tension between these two muscles is critical.

Although there are plenty of strong ligaments around the SI joint, we also have musculature that helps maintain the balance of this joint. The psoas is part of a pair of muscles that help maintain this functional balance. The other muscle in that pair is the piriformis, with some help from other associated muscles (the deep six lateral rotators) at the back of the pelvis. The piriformis and psoas relationship is important for maintaining a healthy balance of tension at the SI joint.

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Fascial relationships

Fascially speaking, the iliopsoas is connected to the entire wall of the abdominal cavity. This includes:

What this means functionally, is that excess tension in any of these areas affects the function in the others. This is a more subtle aspect to discern, but definitely worth considering if you’re having any trouble in these associated areas.

Impacts our breathing

Because of the fascial relationship just discussed, there is a chance that a tight psoas muscle can have an effect on the diaphragm above. Indirectly there may also be a tensional relationship between the psoas and abdominal muscles, which also have a fascial relationship to the diaphragm.

Affects the position of the pelvis

We’ve already mentioned the relationship between the psoas muscle and the piriformis muscle. If you zoom out just a little more, you see a relationship between the psoas muscle and the layers of the gluteal muscles including gluteus minimus, gluteus medius, and gluteus maximus.

This relationship affects a larger area than just the SI joint. Although I wouldn’t exclude the SI joint here, I would add on that this larger relationship starts to affect the position of the pelvis as a whole. It also has a tendency to draw in the quadratus lumborum (QL) muscle. This relationship is part of the larger topic of generalized back pain. The muscular balance of the spine and hip joint, along with all of the musculature that connects them together, can play a role in generalized back pain.

Psoas muscle issues

Tight psoas muscle: Why does the psoas muscle get tight?

The psoas sits at the core of our body and in a sense, the center of our movement. The most fundamental movement we do is walking. Activities that create, in a sense, an excess of this type of movement such as running and cycling, are common causes of psoas muscle tightness. Of course, these movements are often layered on top of patterns of tightness that may already be in place, exacerbating the problem.

For instance, people who sit a lot for work or other reasons, may have a chronically shortened psoas muscle. This essentially happens because the hip is held in a partially flexed position for long periods of time. This means that muscle activity is required, even if just minimally, to maintain this position and relationship between the spine, pelvis, and femur.

If you combine all of these activities together, you cover a large portion of the population. Walking, running, and cycling are probably the most common physical activities that people do. Sitting for long periods, represents what a large part of the population ends up doing between their movement activities. These are not the only activities that can cause tension, just the most common.

What are the symptoms of a tight psoas muscle?

The symptoms of a tight psoas muscle can certainly vary. Some may be more obvious than others. The real difficulty when assessing your problem, a client’s problem, or a student’s problem, is that the psoas has become a catch-all. What I mean by that is it has become easy to jump to the conclusion that a problem in the back, hip, or surrounding areas is because of the psoas. It may be, just don’t jump to any conclusions too quickly.

Having said that, here is a list of things that MAY lead you down the path of recognizing a tight psoas muscle:

  • Lower back pain
  • A pelvis that is tilted forward more than average
  • Hyperlordotic curve in the lumbar spine (May go with the list item above)
  • Difficulty lifting your leg
  • Knee pain
  • A functional leg length difference
  • Constipation
  • Menstrual cramps
  • Feeling exhausted
  • Restricted breathing
  • The feeling that your legs are weak
  • The feeling of having a “compressed” hip joint

Psoas syndrome or iliopsoas syndrome

There is a group of common conditions that are referred to as “psoas syndrome”. The primary symptom is pain in the area where the lumbar spine and the sacrum meet one another. This is called the lumbosacral region. Be mindful that this can also include the sacroiliac joint. The pain is typical when sitting and standing, and worsens when doing any of the following movements:

  • Bending at the hip joint
  • Walking
  • Climbing stairs
  • Squatting
  • Sitting for prolonged periods

It’s not typical for the pain to go beyond the knee joint but anything is possible. Other areas of pain include the gluteals, lower abdomen, groin, iliac crest, and even pain on the front of the thigh. Because this is a syndrome, it means you need a diagnosis. That can only be provided by a doctor who should be making diagnoses. If you think that you have this condition, please go to a doctor to confirm whether that is true or not.

Psoas and low back pain

The psoas muscle is often associated with low back pain. The psoas is without a doubt a very important postural and structural muscle. When there is low back pain, we often look to posture as a culprit of this type of chronic pain. The psoas should therefore be part of the assessment of low back pain and its potential cause. However, so far, there is no research that directly points to a relationship between low back pain and the psoas muscle.

The topic of lower back pain is complex and convoluted. Good assessment is the key to addressing all of the possible factors that may contribute to lower back pain. We should not assume that the psoas muscle is the key to resolving this problem. We may need to look at other muscles such as the quadratus lumborum, or even other hip flexors such as rectus femoris, adductors, and tensor fascia latae. These other muscles can also contribute to a pelvic position that is related to the lower back pain.

With respect to lower back pain and the psoas muscle, keep psoas in the mix of possibilities as a contributing factor. But don’t get drawn in to the popularity of the muscle and assume that it lives in a vacuum all by itself. Take a broader perspective, but definitely treat your psoas muscle along with others.

How to avoid psoas muscle problems

The best thing you can do is avoid problems with your psoas muscle. Here are few things that you can do in order to avoid creating or dealing with long term problems with your psoas muscle:

  • Avoid sitting for long periods
  • Add lumbar support when you do sit
  • Back off extreme exercises that tighten the psoas
  • Get a professional massage
  • Pay attention to your hips and pelvic freedom
  • Read Liz Koch’s book ‘The Psoas Book’
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How to find and treat your own psoas muscle

This is probably the main event for many of you. You’re probably here because you believe that you have a problem with your psoas muscle and you want to do something about it! I’m a DIYer myself and am going to do everything to help you find and dare I say treat your own psoas in multiple ways.

It’s important to know that there is a difference between treatment of your psoas with your own fingers and stretching your psoas. Specific manipulation is simply more direct and can address problems in a more nuanced way. If you are unsure at any point in the process, please refer to a professional for direct treatment and manipulation of your iliopsoas muscle. Stretching your psoas muscle may be helpful but it is a more general treatment and often helpful at maintaining what is gained by direct treatment.

The keys to resolving a problem in the psoas are as follows:

  1. Make sure that the problem is a psoas muscle issue.
  2. Find and thoroughly treat the problem consistently for a sustained period of time.
  3. Identify and adjust other activities that may be contributing to the problem.
  4. Did I mention that you need to treat it consistently for a sustained period of time? If your psoas problem is bad, it could take a few months to resolve it, even with direct treatment.

Where to start

I’ve said already that the psoas major muscle shares a distal attachment with the iliacus muscle. But really, it’s more than that. Iliacus and psoas major muscle fibers actually merge together to make that attachment to the lesser trochanter on the femur. They work together most of the time, if not all of the time.

For whatever reason, the psoas major muscle has become popular, but many people have never heard of the iliacus. In my own anecdotal experience, iliacus is the actual problem or contributing to the overall problem about half of the time. You should think of the whole muscle as the iliopsoas muscle and inspect both parts equally. I suggest you start with the iliacus portion of the muscle because it is easier to access and find.

Most people lay down on their back and bend their knees to find these two muscles. You can apply the same techniques I am about to describe. But I suggest that you sit in a chair or sit on the ground with your legs out in front of you. If you’re pregnant, have irritable bowel syndrome (IBS), Crohn’s disease, or other issues with any organs in the area, have a professional do this or do not do this at all.

Finding the iliacus muscle

First, identify your anterior superior iliac spine (ASIS image below). From there, you need to curl your fingers onto the inside surface of your pelvis. You don’t have to go in too far, about an inch or so should be enough to check that you are on the right spot. It’s helpful to round forward a little in your spine to make sure your abdominal muscles are not contracted. After you have your fingers on the inside surface of your pelvis, slowly lift your leg up slightly on the same side. Think of lifting your entire foot off the floor. It won’t take much for a muscle to contract under your fingers. When it contracts it should push your fingers forward slightly and inward toward your midline.

ASIS of the Pelvis
iliacus muscle palpation
Note that the fingers are on the inside surface of the pelvis.

Finding psoas major

If you want to find your psoas major muscle, start from the same location you left off when first finding your iliacus. Then slowly slide your finger toward your midline. When you try to lift your entire foot this time, your psoas major muscle feels more like a line of tissue that is running vertically rather than flat and pushing your finger inward.

Here are a few things you may want to pay attention to:

  • Is one side of your iliacus or psoas major larger than the other?
  • Is one side of your iliacus or psoas major more tender than the other?
  • Did you have a harder time lifting your leg on one side when it had pressure on the muscle?
  • Did you notice any other differences between the two sides?
the psoas muscle palpation
Note that the fingers are off the inside of the pelvis and now heading in the direction of the spine.

Treating your iliopsoas muscle

Finding your iliacus and psoas major are one thing, treating them is something completely different. This is of course, the domain of a professional, but there are a variety of simple things you can do yourself that may make all of the difference in your particular situation.

  • Just gently pressing and releasing as much of the muscle as possible would be a basic treatment. Contract and relax along the way so you know you are still on the muscle.
  • Press more firmly when the muscle is relaxed, particularly on areas that are more tender than the area that surrounds that tender spot.
  • You can also press and hold these areas for a longer period of time. Not more than about 30 seconds.
  • You can also hold these areas and get the muscle to contract while holding it.
  • Holding the muscle and stretching it may also be useful.

Do I need to strengthen or stretch my psoas?

It’s also important to realize that you need to assess your iliopsoas properly before you decide how to treat it. Some of you may show up to this section with the idea that your iliopsoas is tight. Some of you may be wondering how to strengthen it. Keep in mind that your iliopsoas muscle may be weak because it is too tight! Applying strengthening techniques because you think it is weak may be the wrong thing to do if it’s weak because it’s already too tight. You’re then tightening a muscle that is already too tight.

Stretching your psoas muscle

There is some debate as to whether you can truly stretch your psoas enough to undo tension in it. Part of the reason for this is because of the depth of this muscle. This means that you would need to take your legs into hyperextension to stretch it. This is exactly why you often see some form of lunges used to stretch the iliopsoas muscle.

In order for this to work, all of the more superficial muscles have to be stretched “long” enough to allow you to get to the iliopsoas and lengthen it. It’s not that hyperextension isn’t possible, it obviously is. It’s also not that you can’t stretch the psoas at all when your leg is in hyperextension, you can. The question is, how effective is it to stretch your psoas when the impact of the stretch itself may be minimized by iliopsoas’s depth and difficulty isolating that tissue? Having said all of that, there is no harm in trying to generally maintain openness of the tissues on the front of the body, including the iliopsoas.

Have a relationship with the psoas muscle

Whenever I talk about the iliopsoas muscle in workshops I say something like: Before you decide whether you need to stretch or strengthen your iliopsoas, you should have a relationship with it. What do I mean by that? I mean that you should have some sense of what it means to connect to this muscle in a way that helps you create movement from it.

What makes this difficult is that your psoas muscle is not like your biceps that you are able to feel, see, and touch easily. The sensory response from your biceps muscle is different from the sensory information that you might get from your iliopsoas muscle. You want to develop this relationship over time. How do you do this? You start with intention.

As a yoga teacher, I do exercises of palpation (touching) with the iliacus and psoas major muscles as I described above. But by far, the best place to start this intention is in sun salutations. Here’s me leading sun salutations in a London workshop so you get a sense of what I’m talking about. As you build a better relationship with iliopsoas, you’ll start to know what it needs and when it needs it.

These same principles could and should be applied to lifting up and jumping back if you do a vinyasa style practice. Even though you’re using your arms to lift up, you want the intention of connecting that lift to your lower abdomen and particularly your psoas muscle.

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If you’ve made it this far down this article, you know how complicated and important the iliopsoas muscle truly is. It is after all, our center of movement physically, and overlaps with energetic principles and concepts from a number of different traditions. You should now have a good grasp of where the psoas muscle is located, its function and many of its dysfunctions. Most importantly I hope that you have a broader perspective for assessing what is going on and some good ways of avoiding trouble with your psoas muscle. If you do have trouble, you should now be able to distinguish between treating your psoas and only stretching the psoas muscle.