The Psoas Muscle

May 14, 2014
The Psoas Muscle

What does psoas muscle mean?

The Psoas Muscle

  • Psoas literally means “muscle of loin” (Greek).
  • Three muscles are associated with what is commonly referred to as “the psoas muscle”: the psoas major, psoas minor, and iliacus.
  • The psoas major is the larger of the two psoas muscles.
  • The psoas minor is the smaller of the two psoas muscles and is absent in approximately half the human population.

Where does the psoas muscle attach?

  • The psoas major’s proximal (closest to the head) attachment is on the sides of the bodies of the vertebrae from T12 through L4. It continues down the sides of the spine, over the front of the pubic bone, and then attaches at the distal end, with the fibers of the iliacus, to the lesser trochanter of the femur.
  • The psoas major crosses many joints: T12–L1, L1–L2, L2–L3, L3–L4, L4–L5, L5 – sacrum, sacrum–ilium (SI joint), pubic symphysis, and the hip joint.
  • The iliopsoas connects the upper half of the body to the lower half of the body.

The Psoas Muscle Attachments

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What are the actions of the psoas muscle?

  • We often group iliacus and psoas major together as the “iliopsoas” when referring to the function of either individual muscle.  The primary function of the iliopoas is to flex the hip joint.
  • Secondarily, the iliopsoas externally rotates the hip joint.
  • It can also be involved with adduction of the hip if the hip has already been abducted or taken out to the side.
  • Because of its location, the psoas muscle is ALWAYS associated with the “core” of our body.
  • It directly impacts the quality and lightness of our movement because of its relationship to our center of gravity. See my old article on the psoas for more details about moving from your center.

Postures where this muscle contracts


In kurmasana (below), you’ll find the psoas muscle contracting.

upavishta konasana

In upavishta konasana (below), the psoas contracts, as well.

navasana or boat pose

Navasana (below) is not just about the abdominals. Deep to the abdominals, you’ll find that the psoas contracts strongly.

Postures where this muscle is lengthened


Dhanurasana (below) lengthens the psoas muscle.

supta virasana

Virasana (below) not only lengthens the quadriceps, but the psoas too.

pigeon pose

In the back leg of pigeon posture (below), the psoas is getting lengthened.

Psoas muscle injury

Psoas syndrome/overuse:

The psoas, like the iliacus, can become sore from repetitive use/stress, either from daily activities like long periods of sitting, or through a sport like running or cycling.

You might experience pain directly at the iliopsoas when you sit for long periods, for example, when you drive a car for a long distance. Additionally, you might feel referred pain in other areas of the body, like the lower back.

Resting the muscle by taking a break from your activity can help alleviate acute pain. Due to where the psoas is located deep in the body, a skilled professional body worker may be needed to treat psoas syndrome/overuse.

Psoas strain or tear:

If we accompany psoas overuse with a certain amount of force, we can get an actual tear in the psoas. To describe how severe the tear is, we give them grades of 1, 2, or 3.
A grade 1 tear is a small tear. You might have some pain, but you likely retain full muscle function.
If you have a grade 2 tear, then you have a larger tear, with some loss of muscle function.
Finally, if you have a grade 3 tear then you have torn most muscle fibers and you have a major loss of muscle function.

Trigger points

Iliopsoas Trigger Points