The Iliopsoas Muscle:
The Hidden Root of Pain

The Hidden Prankster

The iliopsoas muscle is referred to as a “hidden prankster” in Myofascial Pain and Dysfunction: The Trigger Point Manual, the seminal two-volume master work by Janet Travell M.D. and David Simons, M.D. They could hardly have come up with a more fitting label for this complex muscle. The iliopsoas serves numerous key functions in the body, often becomes painful, and can also be responsible for a variety of postural distortions and compensations. Among the most common problems caused by iliopsoas dysfunction is lower back and hip pain.

Two Muscles in One: Location and Attachments

The iliopsoas is actually two muscles: the psoas muscle and the iliacus muscle.

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IMAGE: Iliopsoas shown as the unity of the two muscles

IMAGE: The psoas and iliacus shown individually

The psoas major muscle attaches along the lumbar spine and intervertebral discs then descends obliquely to attach at the lesser trochanter of the femur.

The iliacus muscle attaches to the upper two-thirds of the iliac fossa then descends to join the psoas major tendon, with some of its fibers attaching directly to the femur near the lesser trochanter.

The Iliopsoas Has Many Key Functions

The primary function of both the psoas and iliacus is hip flexion, also known as flexion of the thigh. In other words, these muscles lift the knee to take a step in walking. When you ascend stairs, the iliopsoas must lift the knee higher and therefore must work a little harder. Both muscles can assist in thigh abduction (raising the leg away from the body) and, to some extent, external thigh rotation as well.

Due to its attachment along the spine, the psoas plays a major role in maintaining upright posture. It can assist in extending the lumbar spine and, when excessively short, can contribute to excessive lumbar lordosis. During sitting and standing, the psoas remains active. The iliacus may or may not be active during sitting and is often active during standing.

The Anchor of Iliopsoas Syndrome

One very common problem of the iliacus and psoas is that they both can shorten over time, especially in those individuals who sit for long periods of time. Prolonged sitting in which the muscles are in a shortened state for extended periods of time can lead to the muscles getting used to this position. Put another way, the muscles often adapt to a shortened position.

Once in an adapted state, muscles have trouble returning to their normal resting length. This is a basic characteristic of muscle function. The Cross-Bridge Theory which attempts to explain the contractile action of muscle tissue asserts that, once contracted, a muscle cannot lengthen on its own. The contractile units of the muscle (sarcomeres) must be stretched back to their original resting length by an outside force ( such as an opposing muscle group) before the muscle is able to actively contract and relax again.

You might ask, Can’t you just stretch the muscle out then? In some cases, yes, if the proper type of stretching is done consistently, day in and day out. But in some cases the fibers of the muscle become adhered together, or stuck. When this occurs it’s often necessary to release the muscle with manual therapy techniques (see What to Do section below).

Consequences of Chronic Muscular Contraction

If a muscle cannot return to its normal resting length, it then resides in a state of chronic contraction. Numerous undesirable consequences can result:

1) A chronically contracted muscle can become ischemic (low blood flow). Imagine the white knuckles of a clenched fist. No blood flow there. An ischemic muscle is often a painful muscle.

2) A chronically contracted muscle can develop trigger points which refer pain (or numerous other possible sensations – thermal, tingling, numbness, aching) either radiating out from the muscle or felt in other parts of the body.

3) A chronically contracted muscle can distort the movement of the joint it crosses. For example, a chronically tight iliacus could reduce movement at the front of the hip.

4) A chronically contracted muscle can cause other compensations or distortions in the body. If a chronically tight iliacus, for example, reduces movement in one hip, then the other hip or the spine or other parts of the body will be called upon to compensate or to change their normal pattern of movement.

5) A chronically contracted muscle may be responsible for entrapment of nerves, another cause of pain. In the case of the iliopsoas, entrapment of the following nerves is possible: the femoral nerve, the lateral femoral cutaneous nerve, the femoral branch of the genitofemoral nerves, the iliohypogastric nerve and the ilioinguinal nerve.

Potential Regions of Pain

What this means for an individual whose psoas and/or iliacus is tight and short and ischemic (low blood flow) is that pain might be experienced in any of a variety of places in the body. During my nearly twenty years of treating iliopsoas dysfunction, clients have presented with pain in following areas of the body:

• Lower abdomen
• Groin
• Buttocks
• Down the leg
• Hip
• Lower back
• SI Joint
• Across the top of the hip bone (iliac crest), sometimes wrapping around to the lower back or buttocks.

The problem an individual may face when being examined by a physician not trained in soft tissue problems is that examination of any of the above areas of pain may reveal exactly nothing. Many standardized allopathic tests, including neurologic tests, will come back negative because they are not tests designed to evaluate soft tissue problems. Such problems can only be properly assessed with skilled palpation and knowledge of what you’re looking for. Of particular difficulty in the case of the iliacus is the fact of its hidden location. This muscle is not easy to palpate if you don’t have any practice at it. The psoas is more accessible but no less intimidating to palpate, much less treat, if you’re unsure what to do.

What To Do

Treatment of iliopsoas syndrome requires patience and skill. In the coming year I hope to have available a short video demonstration presenting how to do it. Until then I offer two solutions:

1) If you’re in contact with a health practitioner (physician, massage therapist, physical therapist) who you know and trust, you might suggest they employ the following instructions (taken from the manual I wrote many years ago for use in my Neuromuscular Therapy classes):

The Iliopsoas Muscle: Instructions for Manual Therapy Treatment

2) A trained Neuromuscular Therapist should know how to properly treat iliopsoas dysfunction. Call St. John Seminars at 888-NMT-HEAL Extension 4 (Administration) and ask for the directory of practitioners to locate a therapist in your area. St. John Seminars teaches and keeps a current directory of Neuromuscular Therapists nationwide.

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