Section 01 of 20
Introduction
Psoas major is a long, thick muscle that lies deep in the abdomen beside the lumbar spine. It arises from the sides of the lower thoracic and lumbar vertebrae, runs down along the brim of the pelvis, passes in front of the hip joint, and ends in a tendon on the femur.
It is one of the few muscles that connects the trunk to the leg directly. The lumbar plexus is embedded within it, and the kidney, ureter, and large blood vessels lie in front of it. At the pelvis it joins iliacus to form the iliopsoas tendon.
Section 02 of 20
Origin
| Origin | The sides of the vertebral bodies and intervertebral discs from T12 to L5, and the transverse processes of L1–L5. |
|---|
An anatomical image for this section will be added when verified source media becomes available.
Section 03 of 20
Insertion
| Insertion | The lesser trochanter of the femur, by a common tendon with iliacus (the iliopsoas tendon). |
|---|
An anatomical image for this section will be added when verified source media becomes available.
Section 04 of 20
Actions
No dedicated action video is currently available. This movement is explained below and video will be added when verified source media becomes available.
| Primary action | Hip flexion. |
|---|---|
| Secondary actions | Trunk flexion when the legs are fixed, lumbar stabilization and lateral flexion, and weak lateral rotation of the thigh. |
| Movement at the joint | Hip joint and the lumbar spine. |
| Heads / fiber groups | Single long muscle (a psoas minor is present in some people); joins iliacus as iliopsoas. |
| Functional examples | Walking and running; climbing stairs; sitting up from lying; kicking. |
Hip flexion
The strongest flexor of the thigh at the hip, especially when lifting the leg above the level of the hip.
Trunk flexion
When the legs are fixed, it bends the trunk forward, as in sitting up from lying.
Lumbar stabilization and lateral flexion
Helps stabilize the lumbar spine and bends the lumbar spine to the same side when one side works.
Weak lateral rotation of the thigh
May assist a small amount of outward rotation of the thigh.
Section 05 of 20
Nerve Innervation
| Nerve | Anterior rami of the lumbar nerves L1–L3 (some sources list L2–L4), directly from the lumbar plexus. |
|---|
The lumbar plexus lies within the muscle, and the femoral nerve leaves it near the pelvis. Numbness or weakness in the thigh, a knee that gives way, or pain that spreads down the leg may reflect nerve problems, not only muscle tightness.
Section 06 of 20
Blood Supply
| Blood | The lumbar branches of the iliolumbar artery and the lumbar arteries, with iliac branches near the pelvis. |
|---|
Section 07 of 20
Pictures and Visual Anatomy
An anatomical image for this section will be added when verified source media becomes available.
Section 08 of 20
Functional Movement
Psoas major lifts the leg with each step of walking and running, is used heavily when climbing stairs, sitting up, and kicking, and is held in a shortened position by prolonged sitting. It also works constantly to steady the lumbar spine.
Section 09 of 20
Synergists and Antagonists
Synergists: iliacus (with psoas major as the iliopsoas), rectus femoris, sartorius, pectineus, and tensor fasciae latae (hip flexion), and the abdominal muscles for trunk flexion. Antagonists: gluteus maximus and the hamstrings (hip extension), and the back extensors (trunk extension).
Section 10 of 20
Palpation and Location
Client position and technique
Palpation is indirect and needs clear consent and communication. Position the client supine with the knees bent and supported and the abdomen relaxed. Lateral to the rectus abdominis, at about the level of the navel, wait for the abdominal wall to soften with slow exhalations, and then gently and slowly sink the fingers toward the spine. Ask the client to lift the foot a small distance to feel the deep muscle tighten.
Protect nearby structures
The abdominal aorta, the inferior vena cava, the iliac vessels, the kidney, the ureter, and the bowel lie close to the muscle. Use slow, light pressure, stay lateral to any pulse, and stop at pain, tingling, nausea, or unusual pulsation. Avoid the area in pregnancy, after recent abdominal surgery, and with a known aneurysm, and never use deep abdominal pressure in a client with abdominal pain of unknown cause.
Section 11 of 20
Massage Therapy Relevance
Psoas major is frequently discussed in relation to hip flexor tightness, anterior pelvic tilt, a sway back posture, and low back and front-of-hip discomfort in people who sit for long periods. Many other structures cause similar symptoms, and abdominal causes must be considered.
Section 12 of 20
Dysfunction: What Happens When Movement Goes Wrong
Changes in how a muscle works can change how a joint moves. The points below describe possibilities that may be associated with altered muscle function; they are not diagnoses, and one muscle is never assumed to be the sole cause of a problem.
When the muscle is weak
Weakness may reduce the ability to lift the leg and may be associated with a shorter stride and more work by the rectus femoris and tensor fasciae latae.
When it is tight or shortened
Tightness may be associated with limited hip extension, an increased lumbar curve, and front-of-hip or low back ache, especially after long periods of sitting.
When it is overused
Repeated hip flexion in running, kicking, and cycling may overload the muscle and tendon and may contribute to groin or front-of-hip pain.
When it is strained
A strain may cause deep groin or front-of-hip pain with resisted hip flexion; hip joint, hernia, and lumbar causes can look similar.
When it is inhibited or others compensate
Reduced activation may be associated with poor hip flexion control and more work by the rectus femoris and other flexors.
When it does not coordinate well with synergists and antagonists
Poor coordination with iliacus, the abdominals, and gluteus maximus may alter pelvic position and lumbar control and may be associated with low back or hip symptoms.
Section 13 of 20
Conditions, Pathologies, and Pain Relationships
Hip flexor tightness
A shortened psoas may limit hip extension and may be associated with increased lumbar curve and front-of-hip or low back ache.
Psoas strain and tendinopathy
Sprinting, kicking, and sudden hip flexion can strain the muscle or tendon and cause groin or deep front-of-hip pain.
Snapping hip (internal)
A snap or catch at the front of the hip may involve the iliopsoas tendon moving over the hip joint or pelvis.
Differential considerations
Hip joint disease, hernia, lumbar disc and nerve problems, kidney and ureter problems, gynecologic and bowel conditions, and psoas abscess can all cause groin, flank, or low back pain.
Section 14 of 20
Example Clinical Relationship
An office worker who sits for many hours reports a deep ache at the front of the hip when standing up and an increased arch in the low back. Psoas major may be shortened, and the pattern may be associated with hip flexor tightness, but hip, lumbar, and abdominal problems can look similar. Gentle work on the front of the hip may support comfort, while fever with deep hip or back pain, a pulsating mass, or new leg weakness needs referral.
Section 15 of 20
Massage and Treatment Approaches
For healthy, non-acute tissue, use secure draping and clear consent. Begin with light effleurage and gentle compression along the anterior thigh and hip flexors, add gentle hip mobilization within comfort, and keep any indirect abdominal work brief, light, and guided by the client's feedback.
| Positioning | Supine with the knees bent and supported by a bolster, or side-lying with the top leg supported. |
|---|---|
| Regional work | Consider iliacus, rectus femoris, tensor fasciae latae, sartorius, quadratus lumborum, the abdominals, and the low back when assessment supports it. |
| Avoid | Deep pressure in the abdomen, over a pulse, or at any point that reproduces leg pain or tingling, and any pressure in pregnancy or with abdominal pain of unknown cause. |
Section 16 of 20
Precautions and Contraindications
Precautions and contraindications
- Pregnancy, recent abdominal or pelvic surgery, or a known abdominal aortic aneurysm: do not perform deep abdominal work.
- Use caution with hernias, inflammatory bowel disease, kidney disease, or abdominal pain of unknown cause.
- Use caution with anticoagulant use or easy bruising.
- Always obtain explicit consent and use secure draping for hip and groin work.
Section 17 of 20
Red Flags and When to Refer
Red flags and referral
- Severe or worsening abdominal or flank pain, fever, or a pulsating mass in the abdomen.
- Deep hip, groin, or back pain with fever, night sweats, or unexplained weight loss (possible infection or abscess).
- A groin bulge, blood in the urine, or sudden severe hip pain after a fall or inability to bear weight.
- New leg weakness, numbness in the thigh or saddle area, or bladder or bowel changes.
Section 18 of 20
Study Summary
Attachments
Origin: T12–L5 vertebral bodies and discs and L1–L5 transverse processes. Insertion: lesser trochanter.
Actions
Strongest hip flexion; lumbar stabilization; trunk flexion when the legs are fixed.
Supply
Lumbar plexus, anterior rami L1–L3; lumbar and iliolumbar arteries.
Section 19 of 20
Instructor Narration
Open narration transcript
Psoas major is the long deep muscle that connects the lumbar spine to the femur and is the strongest hip flexor.
It arises from the sides of the vertebral bodies and discs from T12 to L5 and the lumbar transverse processes, and inserts on the lesser trochanter of the femur with iliacus.
It flexes the hip, bends the trunk forward when the legs are fixed, and stabilizes the lumbar spine. Iliacus, rectus femoris, and sartorius help it, and gluteus maximus and the hamstrings oppose it.
The anterior rami of L1 to L3 supply it directly from the lumbar plexus, and the lumbar and iliolumbar arteries provide its blood.
Palpation is indirect. Obtain consent, place the client supine with the knees bent, wait for the abdominal wall to soften, and press very gently. Stay lateral to any pulse and stop at pain, nausea, or tingling.
Hip flexor tightness, strain, snapping hip, hernia, nerve problems, and abdominal conditions can overlap. Refer a pulsating abdominal mass, severe pain, fever with deep hip or back pain, a groin bulge, new leg weakness, or bladder or bowel changes.
Remember: T12 to L5 and the lumbar transverse processes to the lesser trochanter; hip flexion; lumbar plexus L1 to L3.
Section 20 of 20