Iliopsoas

Question 1

Where does the iliacus originate?

Answer 1

The iliacus originates from the iliac fossa on the interior of the hip bone.

Question 2

Where does the psoas major originate?

Answer 2

The deep portion of the psoas major originates from the transverse processes of lumbar vertebrae I-V. The superficial part arises from the lateral surfaces of the last thoracic vertebra, lumbar vertebrae I-IV and the neighboring intervertebral discs.

Question 3

Where does the iliopsoas insert?

Answer 3

The iliopsoas inserts into the lesser trochanter of the femur.

Question 4

Which nerves innervate the iliacus?

Answer 4

The iliacus is innervated by the femoral nerve and direct branches from the lumbar plexus.

Question 5

Which nerves innervate the psoas major?

Answer 5

The psoas major is innervated by the lumbar plexus via the anterior rami of L1 to L3 nerves.

Question 6

Which movements does the iliopsoas contribute to?

Answer 6

Because the iliacus attaches to the inside of the hip, it contributes only to hip flexion (and medial rotation). The psoas major contributes to hip flexion during open-chain exercises, but can also flex the spine upon the hip in closed-chain exercises like a sit-up.