Psoas Muscle – Anatomy Highlight

Psoas anatomy

The psoas muscle comes up frequently with my clients. It may not be as well known as some other muscles like the pecs or hamstrings, but this low key muscle plays an essential role in movement and stability. Due to its attachment points, it can be involved in issues involving the hip, pelvis, and lower back. Whether you’ve heard of the psoas or not, you can undoubtedly benefit from understanding the anatomy of this important muscle and how to train it.

Where is the Psoas?

The psoas muscles originate on either side of the lower spine, with attachment to the last thoracic and all of the lumbar vertebrae as well as the associated intervertebral discs. The psoas forms a complex with another muscle called the iliacus. The iliacus originates on the inside front aspect of the pelvis on each side. From the lower back, the psoas runs down across the front of the pelvis and hips. As it passes through the pelvic region, its fibers blend with those of the ilacus. Just past the hip joint, this combined iliopsoas complex inserts into the back of the inner part of each femur (thigh bone) on a prominence called the lesser trochanter.

Iliopsoas muscle complex

What Does the Psoas Muscle DO?

The iliopsoas complex in simplest terms is a hip flexor. This means that it raises the knee toward the chest when it contracts. Due to its attachments on the lumbar spine, the psoas also contributes to spine stability (it is actually often considered part of the core), side-bending of the lower back, and serves as a major connection between the upper and lower parts of the body. The iliopsoas complex also plays a role in hip stabilization and hip external rotation. We need strength and control in the psoas to comfortably stand upright, sit, walk, run, dance, climb, and ride a bike.

What Issues Can the Psoas Muscle Be Involved In?

Lower Back Pain

Due to its origin in the lumbar spine, the psoas muscle can directly influence the movement and position of the lower back. If the psoas is tight or overactive, it can pull the lower back into extension and cause the pelvis to tilt anteriorly. The resulting tension can create or exacerbate pain in the lower back.

Psoas muscle back pain

Hip Pain

The iliopsoas complex primarily creates movement at the hip joint, also playing an important role in hip joint stability. If this muscle group is not functioning properly, the hip may become stiff, weak, or unstable. All of these issues can cause pain.

Psoas hip pain

Radiating Nerve Pain

There is a bundle of nerves that originates in the lower spine called the lumbar plexus. It contains nerve fibers that control many of the important functions of the hips and legs. After exiting the spinal cord, the lumbar plexus passes directly between the fibers of the psoas. Because of this close relationship, abnormal tension on the psoas can put pressure on these nerves. When nerves are compressed in this way, it can create pain, numbness, or tingling anywhere along the path of the nerve. Thus, the psoas can contribute to nerve-related pain, numbness, or tingling throughout the lower body.

Lumbar plexus

Mobility Routine

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How to Train the Psoas Muscle

I’m going to give three examples of psoas training – strengthening, lengthening mobility, and shortening mobility. Most people immediately want to jump into the lengthening mobility because they feel like their hip flexors are tight. I actually recommend that everyone start with the strengthening drills. Often, the sensation of hip flexor tightness is actually due to weakness or poor control rather than true limitations in muscle extensibility.

Psoas Strengthening

This one is right for you. That’s not a typo. Everyone can benefit from strengthening their iliopsoas complex. I recommend progressing the exercise shown below by taking away the box so that you’re lifting your foot from the floor. Only progress to that next level when the example in the video is feeling too easy.

Lengthening Mobility – Hip Extension

This one is right for you if you have lower back pain, anterior pelvic tilt, and difficulty extending your leg behind your body. Check out the video linked below for the exercise. Again, true tightness is often not the issue. Instead of focusing on a deep intense stretch, emphasize the active muscle contraction component of the exercise.

Shortening Mobility – Hip Flexion

This one is right for you if you have a hard time sinking into a deeper squat, you can’t raise your knee up without your lower back rounding, or if you have a hard time sitting up in a chair with your back straight. Check out the video linked below for the exercise.

Final Thoughts

To quickly summarize, the iliopsoas is an important and under-trained muscle group that can contribute to a wide-range of issues if weak or immobile. I recommend everyone start with strength-training and add in the mobility drills if you are still experiencing problems.

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Health Advice Disclaimer

This article provides examples that are applicable to many, but not all people.  They are based on typical presentations seen in my personal clinical practice.  This information represents common findings in the population discussed, but can in no way take the place of professional evaluation and treatment by a licensed medical practitioner.  It is impossible to provide 100% accurate diagnosis or prognosis without a thorough physical examination and likewise the advice given for management or prevention of any injury cannot be deemed fully accurate in the absence of this examination. 

If you are currently experiencing any pain or injury, seek professional evaluation before undertaking this or any exercise program.  Ensure that you are medically cleared for exercise before undertaking any exercise program.  Significant injury risk may occur if you do not seek proper evaluation.  No guarantees of specific outcome are expressly made or implied in this article. 

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