|Anterior hip muscles. The iliopsoas is not labeled but can be seen as the psoas major and the iliacus join inferiorly.|
|Gray's||subject #127 467|
|Origin||iliac fossa, spine|
|Insertion||lesser trochanter of femur|
|Artery||medial femoral circumflex artery, iliolumbar artery|
|Nerve||femoral nerve, L1, L2|
|Actions||flexion of hip|
|Antagonist||Gluteus maximus, posterior compartment of thigh|
The term iliopsoas 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" or "inner hip muscles". The psoas minor does not contribute to the iliopsoas muscle.
The psoas major is innervated by direct branches off the lumbar plexus at the levels of L1 and L2, 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. The iliacus and psoas major perform different actions when postural changes occur.
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 tone. Such shortening can lead to increased anterior pelvic tilt and lumbar lordosis (unilateral shortening), and limitation of hip extension (bilateral weakness).
The iliopsoas muscle is covered by the iliopsoas 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.
Additional Images 
See also 
- Platzer (2004), p 234
- Thieme Atlas of Anatomy (2006), pp 422-523
- Platzer (2004), p 254
- Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol 1: Locomotor system (5th ed.). Thieme. ISBN 3-13-533305-1. (ISBN for the Americas 1-58890-159-9.)
- Thieme Atlas of Anatomy. Thieme. 2006. ISBN [[Special:BookSources/31314205112|31314205112 [[Category:Articles with invalid ISBNs]]]] Check
|isbn=value (help). (ISBN for the Americas 1-58890-419-9)
- "Iliopsoas". Retrieved 1 September 2010.