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Iliopsoas Anatomy: Origins, Insertions, Actions, Innervations

Iliopsoas Muscles: Ilicacus, Psoas Major, Psoas Minor

Iliopsoas Muscle

The Iliopsoas is a group of three muscles: Iliacus, Psoas Major and Psoas Minor.

Iliacus Muscle O, I, A

  • Origin: Superior two-thirds of the internal surface of the iliac fossa, the inner lip of the iliac crest, the ventral surface of the sacroiliac and iliolumbar ligaments, and the upper surface of the lateral part of the sacrum.
    Insertion: The lesser trochanter of the femur after being joined by the tendon of psoas major.
    Actions: Flexion of thigh at hip, assists in extension of the lumbar spine
    Innervation: Femoral nerve (L2, 3)
    Vascular Supply: Iliolumber artery from internal iliac artery

Primary Actions of the Iliacus:

1. Flexion of thigh at the hip

  Agonists: Psoas Major

  Antagonists:

  • Gluteus maximus
  • Semitendinosus
  • Semimembranosus
  • Biceps Femoris (long head)
  • Adductor magnus (posterior part)

Note: Pectineus, rectus femoris, sartorius, and psoas minor assist with flexion of the thigh at the hip. The adductor longus assistance is important with the initial stages of flexion from full extension.

Psoas Major O, I, A

  • Origin: Anterior surfaces of the vertebral bodies, intervertebral discs and transverse processes of T12-L5 vertebrae.
    Insertion: The lesser trochanter of the femur after being joined by the tendon of the iliacus.
    Actions: Flexion of thigh at hip, assists in extension of the lumbar spine
    Innervation: Lumbar plexus (L2, 3,  4)
    Vascular Supply: Iliolumbar artery from internal iliac artery.

Primary Actions of the Psoas Major:

1. Flexion of thigh at the hip

  Agonists: Iliacus

  Antagonists:

  • Gluteus maximus
  • Semitendinosus
  • Semimembranosus
  • Biceps Femoris (long head)
  • Adductor magnus (posterior part)

Note: Pectineus, rectus femoris, sartorius, and psoas minor assist with flexion of the thigh at the hip. The adductor longus assistance is important with the initial stages of flexion from full extension.

Secondary Actions of the Psoas Major:

2.Assists with extension of the lumbar spine

  Agonists:

  • Iliocostalis lumborum
  • Longissimus thoracis

  Antagonists: Rectus Abdominis

Note: Interspinalis also assist with extension of the lumbar spine.

3. Lateral Flexion of the spine when acting unilaterally

  Agonists:

  • Iliocostalis lumborum
  • Longissimus thoracis
  • Quadratus lumborum
  • External Oblique
  • Internal Oblique

  Antagonists: Same muscles listed above on the opposite side.

Psoas Minor O, I, A

  • Origin: Bodies of T12 and L1 and intervening intervertebral discs
    Insertion: Attaches to the pectineal line, the iliopectineal eminence and the iliac fascia.
    Actions: Flexion of thigh at hip
    Innervation: Ventral primary rami of L1.
    Vascular Supply: Iliolumbar artery from internal iliac artery.

Primary Actions of the Psoas Minor:

Because of its position and size the psoas minor is not a prime mover.

Secondary Actions of the Psoas Minor:

1. Assists with flexion of the thigh at the hip

  Agonists:

  • Psoas Major
  • Iliacus

  Antagonists:

  • Gluteus maximus
  • Semitendinosus
  • Semimembranosus
  • Biceps Femoris (long head)
  • Adductor magnus (posterior part)

Note: Pectineus, rectus femoris, sartorius, and psoas major assist with flexion of the thigh at the hip. The adductor longus assistance is important with the initial stages of flexion from full extension.

 

iliopsoas-feat

Areas and actions that contribute to iliopsoas pain:
Iliopsoas Muscles: Low Back, Abdomen, Groin, Pelvic, Upper Leg Pain