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Anterior Hip Muscles 2.PNG
Anterior hip muscles. The iliopsoas is not labeled but can be seen as the psoas major and the iliacus join inferiorly.
Latin Musculus iliopsoas
Iliac fossa and lumbar spine
Lesser trochanter of femur
Medial femoral circumflex artery and iliolumbar artery
Branches from L2-L4
Actions Flexion of hip
Gluteus maximus and the posterior compartment of thigh
Gray's p.467
TA A04.7.02.002
FMA 64918
Anatomical terms of muscle

The term iliopsoas (ilio-so-as) refers to the combination of the psoas major and the iliacus at their inferior ends. These muscles are distinct in the abdomen, but usually indistinguishable in the thigh. As such, they are usually given the common name "iliopsoas" and are referred to as the "dorsal hip muscles"[1] or "inner hip muscles".[2] The psoas minor does not contribute to the iliopsoas muscle.


The psoas major originates along the lateral surfaces of the vertebral bodies of T12 and L1-L5 and their associated intervertebral discs. The iliacus originates in the iliac fossa of the pelvis.[2]

The psoas major unites with the iliacus at the level of the inguinal ligament and crosses the hip joint to insert on the lesser trochanter of the femur. The iliopsoas is involved in flexion and lateral rotation (supination) of the thigh. If the limb is fixed they involve in flexion of the trunk.


It is a composite muscle. The psoas major is innervated by direct branches of the anterior rami off the lumbar plexus at the levels of L2-L4, while the iliacus is innervated by the femoral nerve (which is composed of nerves from the anterior rami of L2-L4).


The iliopsoas is the strongest of the hip flexors (others are rectus femoris, sartorius, and tensor fasciae latae). The iliopsoas is important for standing, walking, and running.[2] The iliacus and psoas major perform different actions when postural changes occur.

The iliopsoas muscle is covered by the iliac fascia, which begins as a strong tube-shaped psoas fascia, which surround the psoas major muscle as it passes under the medial arcuate ligament. Together with the iliac fascia, it continues down to the inguinal ligament where it forms the iliopectineal arch which separates the muscular and vascular lacunae.[3]

Clinical significance[edit]

It is, however, a typical posture muscle dominated by slow-twitch red type 1 fibers. Therefore, it is susceptible to pathological shortening or contracture, especially in older people with a sedentary lifestyle, and requires regular stretching to maintain normal length. With the advent of computers and sedentary work environments, it affects many younger people too. Such shortening can lead to increased anterior pelvic tilt and lumbar lordosis (unilateral shortening), and limitation of hip extension (bilateral weakness).[2]It is a major contributing factor of scoliosis. Since it originates from the lumbar vertebrae and discs and inserts onto the femur, any structure from the lumbar spine to the femur can be affected. It can cause pain in the low or mid back, SI joint, hip, groin, thigh, knee, or any combination. The femoral nerve passes through the muscle and innervates the quadriceps, Pectineus and Sartorius. It also comprises the intermediate femoral cutaneous nerve and medial femoral cutaneous nerves. Shortening of the muscle can compress any branch of the femoral nerve which can cause pain and dysfunction in any of these muscles, often resulting in leg and knee pain. Due to it's location, it is very difficult to stretch it effectively in the conventional sense.

Additional Images[edit]

See also[edit]

This article uses anatomical terminology; for an overview, see anatomical terminology.


  1. ^ Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol 1: Locomotor system (5th ed.). Thieme. p. 234. ISBN 3-13-533305-1. 
  2. ^ a b c d Thieme Atlas of Anatomy. Thieme. 2006. pp. 422–423. ISBN 3131421010. 
  3. ^ Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol 1: Locomotor system (5th ed.). Thieme. p. 254. ISBN 3-13-533305-1. 

External links[edit]