Iliopsoas muscle

The main mover of your hip joint is the Iliopsoas muscle. It’s formed by the joining of three muscles: the iliacus muscle, the psoas major muscle, and the psoas minor muscle.

These muscles work together to flex your hip and to stabilize your hip and lower back during activities such as walking, running, and rising from a chair.

Your body has two iliopsoas muscles: one at the left hip, and one at the right hip. Injury to the iliopsoas is likely to cause hip pain and limited mobility. 

Anatomy of the iliopsoas muscle

The iliopsoas consists of three distinct muscles. They are usually grouped together due to their common attachment point on your femur (thigh bone).

• Iliacus muscle: The iliacus arises from the inner part of your pelvic bowl on the upper two-thirds of the iliac fossa and the upper lip of the iliac crest. If you imagine your pelvis as a bowl, the iliacus originates from the inner surface on one side of the bowl. The iliacus muscle then courses down through your pelvis and attaches to the lesser trochanter of your femur. 
• Psoas major muscle: This muscle originates at the front surfaces of the vertebral bodies, intervertebral discs, and transverse processes of your spine at thoracic level 12 through lumbar level five. It then courses down through your pelvis and joins the psoas minor and iliacus to insert on the lesser trochanter of your femur.
• Psoas minor muscle: The psoas minor arises from the vertebral bodies and discs of thoracic 12 and lumbar level one. It then inserts along the psoas major in an area called the pectineal line and iliac fascia.

All three muscles arise from different areas of your lumbar spine and pelvic brim, but all three join to insert near the inner portion of your thigh bone near the front of your hip.

There is a fluid-filled bursa that lies near the iliopsoas muscle that helps it glide and slide over the front of your hip during movement.

Blood Supply and Lymphatics

The common iliac artery emits thin branches for the psoas major and minor muscle, while the most important artery for the blood supply of the muscle is the external iliac artery (born from the common iliac), which sends blood branches in its course to the iliacus muscle.

The external iliac vein collects blood from the psoas major and minor muscles and the iliacus muscle; it is the continuation of the femoral vein.

The lymphatic system that involves the iliopsoas muscle is the external iliac lymphatic plexus, at lumbar levels two, three, and four. The psoas minor receives nerve supply from lumbar level one. The iliopsoas muscle gets blood supply from the iliolumbar artery that arises from the internal iliac artery.

 Nerves

The short collateral branches of the lumbar plexus (L1-L3) innervate the psoas major and minor muscles, while the femoral nerve or terminal nerve of the lumbar plexus (L1-L4) innervates the iliacus muscle.

EPIDEMOLOGY

In general, iliopsoas pathologic conditions, such as tendinitis, bursitis, snapping and impingement, have been deemed to be the main cause of chronic groin pain mainly with athletes.  These conditions may cause pain, weakness, and difficulty with basic tasks such as walking, running, and rising up from a supine position.

• Iliopsoas tendonitis: This occurs when the tendons that attach the iliopsoas to your femur become irritated and inflamed. Symptoms of iliopsoas tendonitis may include pain in the front of your hip when flexing your hip, pain with stretching your hip into extension, and difficulty with running. Iliopsoas tendonitis occurs as a result of overuse, and muscular imbalance or tightness and weakness of neighboring muscles may contribute to the condition.
• Iliopsoas bursitis:  irritation of the bursa can result in hip pain and difficulty with flexing and extending your hip. Usually, iliopsoas bursitis does not hurt when forcefully contracting your hip. Rather, the pain occurs when your hip is stretched and the iliopsoas muscle presses into the bursa.
• Snapping hip syndrome: Snapping hip is often caused by tightness of the iliopsoas muscle, allowing it to rub and snap around other bony or ligamentous structures in your hip. It occurs when there is a popping or snapping sensation in the front of your hip while moving it. It’s usually painless, but it can be rather annoying to constantly feel a snapping sensation while moving.
• Weakness of iliopsoas due to lumbar injury:  If you have a low back condition such as herniated discs or lumbar facet arthritis, your femoral nerve may become compressed. This may cause pain in the front of your thigh, and your iliopsoas muscle may become weak as a result. This weakness due to lumbar radiculopathy may make it difficult to walk and rise from a supine position normally. If the weakness is severe, immediate attention may be necessary to get pressure off your nerve and to restore normal nerve function to the muscle.
• Spasm of iliopsoas: Occasionally people with low back pain or hip pain experience iliopsoas spasm. This causes a tight feeling in the front of your hip and makes it difficult to extend your hip backward. 

Rehabilitation

After consulting with your doctor about the source of your hip pain and limited mobility, you may benefit from working with a physical therapist (PT) to treat your iliopsoas condition. Your PT may suggest different treatments for your iliopsoas. Some of these may include the following.

1. Rest: If you have iliopsoas irritation from overuse, resting it for a few days may be advised. Stop doing anything that is causing hip pain. Rest is usually advised, followed by gentle stretches and strengthening exercises.
2. Stretching /mobilizations with movements: if your iliopsoas muscle is tight, your physiotherapist may prescribe stretches. The frequency of the stretches will also be prescribed. Passive end-of-range  overpressure is then delivered without pain as a barrier
3. Low Back Exercise: If a pinched nerve is causing iliopsoas weakness, getting pressure off your nerve may be recommended. Often this is accomplished by performing lumbar stretches like supine lumbar flexion. Check with your PT to determine the correct exercise for your specific lumbar condition.
4. Heat or Ice: Pain in the front of your hip due to iliopsoas injury may be managed by applying ice or heat to the affected area
5. Tapping :this is applied to inhibit or facilitate the muscles in questions

[i]Before starting any treatment for your iliopsoas injury, visit with your physician and PT to ensure you are doing the correct things for your specific condition.