Joe Muscolino

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The iliacus. The psoas major and rectus abdominis have been ghosted in.

The Iliacus is one of the twelve hip joint flexors (open-chain joint action of flexion of the thigh at the hip joint and closed-chain joint action of anterior tilt of the pelvis at the hip joint).

The Hip Flexor Group (from lateral to medial) comprise:



  • Internal ilium to the lesser trochanter of the femur.
    • The proximal attachment is onto the iliac fossa, the AIIS, and the sacral ala



  • Flexes the thigh at the hip joint.
  • Anteriorly tilt the pelvis at the hip joint.
  • Laterally rotates the thigh at the hip joint.
  • Contralaterally rotates the pelvis at the hip joint.



  1. The iliacus and psoas major attach together onto the lesser trochanter of the femur. For this reason, they are sometimes named as one muscle: the iliopsoas.
  2. At the level of the inguinal ligament, the iliacus is usually much wider than the psoas major.
  3. A tight hip flexor muscle can create the postural distortion pattern of excessive anterior tilt of the pelvis, resulting in hyperlordosis of the lumbar spine. This larger postural distortion pattern is known as lower crossed syndrome.