The Iliacus Muscle: Anatomy and Function Explained

The iliacus muscle is a triangle-shaped muscle in the pelvic bone that flexes and rotates the thigh bone. It works with the other muscles in the hip and thigh to help bend, run, walk, sit, and maintain correct posture. Injuries and common medical conditions can affect its function, causing pain and stiffness. Can physical therapy help?

The Iliacus Muscle

The iliacus is one of the body’s most important hip flexor muscles. The iliacus and surrounding muscles work together to produce the stability and range of motion required for bending, dancing, sitting, and walking.

Anatomy

The iliacus muscle is part of a complex muscle system in the hip and pelvis. Two iliacus muscles on each side of the pelvic bone enable the thigh to flex and rotate. They are innervated by the femoral nerve, which provides movement and sensation to the lower limbs. (Bordoni B. and Varacallo M. 2023) The iliacus muscle sits on the wing-shaped ilium and fits into the curved surface of the ilium, called the iliac fossa. The top of the muscle is attached to the upper wings of the ilium or iliac crest. It extends past the hip joint, which connects to the upper thigh bone/femur at the lesser trochanter protrusion. The iliacus is part of a major trio of muscles called the iliopsoas, including the major psoas and minor psoas muscles. These muscles are also attached to the upper femur but extend upward, connecting to the lumbar/lower spine at several attachment points. The iliopsoas also interact with the quadratus lumborum muscle, the deepest muscle of the lower back that starts at the iliac crest and attaches to the lumbar spine at several points. The quadratus lumborum enables flexion and elevation of the spine, while the iliopsoas enable the flexion and rotation of the hip and thigh.

Functions

The iliacus muscle has many functions that include: (Physiopedia, 2024)

• Flexing and rotating the femur.
• Helps maintain proper body posture while standing and sitting.
• Produces hip movement that enables walking, running, and climbing stairs.
• Provides hip flexion – bringing the knee to the chest.
• Enables the forward tilt of the pelvis and side-bending.

Conditions

Several conditions can affect the iliacus muscle, specifically from under and/or overuse injuries. These conditions, collectively known as Iliopsoas syndrome, are typically the result of overuse/repetitive strain or injuries. These include:

• Iliopsoas tendinopathy – which affects tendons.
• Iliopsoas bursitis – which affects cushioning sacs known as bursae.

Iliopsoas syndrome can affect anyone but is common in:

• Individuals and athletes who repeatedly use movements that flex the hips.
• Track-and-field athletes
• Gymnasts
• Dancers

Iliopsoas Bursitis

This is the inflammation of the cushioning sac or bursa under the iliacus muscle, which helps the muscle slide over the pelvic bone. Symptoms can range from mild discomfort to pain that radiates through parts of the leg and hips. Runners, skiers, and swimmers are commonly affected, and individuals who regularly have tight hips and individuals with different forms of arthritis can also be affected. Early treatment can prevent the symptoms from worsening. Mild cases can be treated with self-care and stretching to help relieve tightness, rest, ice application, and over-the-counter nonsteroidal anti-inflammatory drugs. In severe cases, treatment options that may be recommended include: (Physiopedia, 2024)

• Physical therapy
• Assistant walking devices to relieve pressure – for example, a cane.
• Corticosteroid steroid injections
• Prescription anti-inflammatory medications

Iliopsoas Tendinopathy

Another condition affecting the iliacus muscles is iliopsoas tendinopathy, sometimes called snapping hip syndrome, because individuals can hear an audible snapping sound (Davenport KL. 2019). The condition is often experienced by dancers who repeatedly flex and hyperextend their hips and can result in hip and groin pain that gets worse with kicking or rotation. Treatment of iliopsoas tendinopathy can include:

• Retraining muscle imbalances with strengthening and stretching exercises.
• If these fail to provide relief, corticosteroid injections may be used. A saline hydro dissection can relieve stress around the tendon by injecting fluids that cushion and release trapped tissues.
• Tendon release surgery may be recommended when all other options have failed. The surgical release involves severing the tendon to reduce pain and improve the range of motion.

Rehabilitation

Core muscle strengthening is essential to the rehabilitation of iliacus muscle injuries. The iliopsoas is an integral component of the core group and can benefit from stretching and strengthening exercises (Yogateket, 2019)

• Lunge stretches
• Straight leg raises
• Knee-to-chest stretches
• Standing hip flexion with resistance bands
• Certain yoga poses can also help and include variations on the bridge pose that encourage hip flexion. (Yoga International, 2024)

Injury Medical Chiropractic and Functional Medicine Clinic

Iliopsoas pain is often felt at the front of the hips, thigh, mid-back, and lower back. Chiropractic care can help with iliacus muscle injuries through:

Evaluation

• A chiropractor can evaluate the condition and determine if the iliacus muscle is causing pain.

Treatment plan

• A chiropractor can create a personalized treatment plan that may include exercise instructions, manipulation, and other therapies.

Rehabilitation

• A chiropractor can create a rehabilitation program to expedite healing.

Injury Medical Chiropractic and Functional Medicine Clinic works with primary healthcare providers and specialists to develop an optimal health and wellness solution. We focus on what works for you to relieve pain, restore function, and prevent injury. Regarding musculoskeletal pain, specialists like chiropractors, acupuncturists, and massage therapists can help mitigate the pain through spinal adjustments that help the body realign itself. They can also work with other medical professionals to integrate a treatment plan to resolve musculoskeletal issues.

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Hip Labral Tear and Chiropractic Care

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References

Bordoni, B., & Varacallo, M. (2024). Anatomy, Bony Pelvis, and Lower Limb, Iliopsoas Muscle. In StatPearls. www.ncbi.nlm.nih.gov/pubmed/30285403

Physiopedia. (2024). Iliacus. www.physio-pedia.com/Iliacus

Physiopedia. (2024). Iliopsoas bursitis. www.physio-pedia.com/Iliopsoas_Bursitis

Davenport KL. (2019). The professional dancer’s hip. Performing Arts Medicine, 77-87. doi.org/https://doi.org/10.1016/B978-0-323-58182-0.00009-2

Yogateket. Lizette Pompa. (2019). Essential yoga body parts. Hip flexor/psoas and yoga. Yogateket. www.yogateket.com/blog/hip-flexor-psoas-and-yoga

Yoga International. Amber Burke. (2024). 8 poses for iliopsoas release. yogainternational.com/article/view/8-poses-for-iliopsoas-release/