Iliopsoas Muscle Group: Psoas Minor, Psoas Major, and Iliacus

The Iliopsoas muscle group is located in the low back and is made up of the Psoas Minor, the Psoas Major, and the Iliacus.

Psoas Minor

(Absent in approximately 40% of the population).

Anatomical Attachments:

• Origin: Attaches to the sides of T12 and L1 and sometimes L2 vertebrae, and the corresponding disc.
• Insertion: Attaches to the pectineal line, the iliopectineal eminence and the iliac fascia.

Action: Flexes the pelvis and aids in flexion of the lumbar vertebral column.

Nerve Supply: L1 or L2 nerve.

Psoas Major

Anatomical Attachments:

• Origin: Attaches to the transverse processes, the bodies, and the discs of T12 and all the lumbar vertebrae.
• Insertion: Attaches to the lesser trochanter of the femur.

Action: Flexes the thigh and vertebral column. This is an important postural muscle.

Nerve Supply: Lumbar plexus L2 and L3.

Iliacus

Anatomical Attachments:

• Origin: Attaches to the superior 2/3 of the iliac fossa, the iliac crest, from the anterior sacroiliac and the iliolumbar ligaments and the base of the sacrum.
• Insertion: Attaches to the tendon of the psoas major, and the lesser trochanter of the femur.

Action: Flexes the thigh.

Nerve Supply: Femoral Nerve (L2, L3, L4).

Iliopsoas Group (Psoas Major, Psoas Minor and Iliacus)

Synergist:  

• Prime Movers: Pectineus, Tensor fascia latae, Adductor brevis, Sartorius.
• Accessory Movers: Adductor longus and magnus (anterior part), Gracilis, Gluteus minimus, Quadratus Lumborum.

Antagonist: Gluteus maximus, Adductor magnus (posterior part).

Click for Iliopsoas Group Muscle Test 

Click for Iliopsoas Maneuver 

Click for Figure Four Maneuver 

Nerve Entrapment: As most practitioners have not been taught to examine the anterior aspect of the iliopsoas or pelvic floor muscles, there is a high prevalence of the population who has low back, hip, abdominal and pelvic symptomatology that is directly related to these two muscle groups. Hypertonicity of the pelvic floor spills over to the iliopsoas; which is frequently observed in tension related myalgia. Persistent hip flexion yields a mechanically shortened iliopsoas, which can be independently tested through the psoas maneuver. In this highly surgerized region of the body, trigger points have the tendency to form in the scar tissue. Therefore, the practitioner is not only assessing for trigger points, nerve compression, reflex pain from visceral disease, but a high preponderance of possible nerve entrapment. Any one or more of the following nerves may become entrapped. Studies devoted to specific syndromes associated with each nerve have not been performed at this time. Therefore, segregation of symptomatology is obscure. The nerves that may become entrapped are the iliohypogastric, ilioinguinal, lateral femoral cutaneous, femoral nerve, obturator nerve, and genitofemoral nerve. Entrapments of these nerves elicit pain or paresthesia in the low back, lower quadrants of the abdomen, pelvis, and genitalia. If the triggers are active in the iliopsoas, they can elicit pain to these same regions, in addition to the hip and superior anterior thigh. As hypertonic muscles give rise to active TrPs, structural deviation, and compressed or impinged nerves and vessels, a practitioner may be presented with a broad array of symptomatology.

Vascular supply: Iliac branch of the iliolumbar artery.

• Primary: According to Travell and Simons, if there is only one side involved, the pain distribution will be vertical along the lamina of the lumbar region. Should there be bilateral involvement; the referral pattern is described as being horizontal, across the back in the vicinity of both iliac crests. It is easy to determine unilateral or bilateral involvement through the performance of a Psoas maneuver. However, it is more difficult to palpate the triggers in this muscle group, due to the location and possible increased abdominal girth of an individual. The most superior TrPs refers into the back, and can be confused with the boring pain of an iliac aneurysm. The medial TrPs refers into the low back and sacroiliac (SI) region; and individuals who have this trigger active, frequently qualify their hip pain as deep aching or boring in the SI joint region. The most inferior TrPs refers pain to the low back, superior anterior or medial thigh, as well as into the genitalia of the individual.
• Satellite or associated triggers: Rectus abdominis, Hamstrings, Gluteal, Quadratus Lumborum, Rectus femoris, Tensor fascia latae, Pectineus, Pelvic floor muscles, lumbar paraspinal muscles and the contralateral iliopsoas.

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Trigger Point Signs and Symptoms: The individual usually sleeps on one side in the fetal position; thus allowing for mechanical shortening of the muscle which reduces low back pressure and discomfort. Upon rising from bed or persistent sitting, low back discomfort is experienced in addition to shortened hamstrings, however, upon walking for a few minutes the low back discomfort and taut hamstrings usually subside. Frequently, low back discomfort is worsened by fecal impaction, which can apply pressure to the triggers in the iliopsoas. As previously stated, the most frequent complaints are that of low back and hip pain, anytime practitioners are confronted with these complaints, or the individual’s inability to perform crunches or sit-ups, they should conduct the Psoas maneuver.

Trigger Point Activating and Perpetuating Factors: Prolonged sitting with their low back in a jack knifed position (e.g. car riding, truck drivers’ syndrome, and sleeping in a fetal position), stress overload, low back sprain/strain, post surgical adhesions, and increased abdominal girth.

Differential Diagnosis: Quadratus lumborum syndrome, Appendicitis, Degenerative disc disease, (Segmental, Subluxation, Somatic dysfunction) L1 L2 L3 L4 or L5 radiculopathy, S2 or S3 nerve compression, Sciatica, Intervertebral stenosis, Lymphatic cancer, Lymphogranuloma venereum, Neurofibroma, Trochanteric bursitis, Rheumatoid arthritis, Osteoarthritis, Amyloidosis, Cirrhosis, Crohn’s Disease, Colon polyps, Intestinal Obstruction, Irritable bowel syndrome, Leukemia, Surgical adhesions, Systemic Lupus Erythematosus, Aortic aneurysm, Iliac artery aneurysm, Sprain/Strain of the low back, Bone cancer, Bone fracture, Obesity, weakened abdominal muscles, Bladder infection, Kidney cancer, Peritonitis, Kidney stones, Kidney infection, Spontaneous abortion (Miscarriage), Endometriosis, Ovarian cancer, Ovarian cysts, Pelvic inflammatory disease, Uterine cancer, Prolapsed uterus, Cervicitis, Uterine fibroids, Pregnancy, Menses, Genital herpes, Vaginitis, Vulvitis, Rectocele, Prostrate cancer, Prostatitis, Testicular cancer, Testicular torsion, Epididymitis, Hydrocele, Varicocele, Inguinal hernia, Umbilical hernia, Systemic infections or inflammation, Nutritional inadequacy, Metabolic imbalance, Toxicity, Side effects of medication.

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