Iliopsoas

Iliopsoas
Anterior hip muscles. (Psoas minor not pictured.)
Details
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
Identifiers
Latin	musculus iliopsoas
TA98	A04.7.02.002
TA2	2593
FMA	64918
Anatomical terms of muscle

The term Iliopsoas refers to the combination of three muscles:

• psoas major
• psoas minor
• iliacus

These muscles are distinct in the abdomen, but in the thigh, they are usually indistinguishable, and so in that context, they are usually given a common name. They are occasionally labelled "dorsal hip muscles" or "inner hip muscles".

Origin

Psoas major originates along the lateral surfaces of the vertebral bodies of T12 and L1-L4 and their associated invertebral discs. Psoas minor, present in only some 50 per cent of the population, originates at the transverse processes of L1-L5. Iliacus originates in the Iliac fossa of the pelvis.

Insertion

Psoas major unites with iliacus at the level of the inguinal ligament and crosses the hip joint to insert on the lesser trochanter. Psoas minor inserts at the iliopectineal arch, the thickened band at the iliac fascia which separates the muscular lacuna from the vascular lacuna.

Properties

Strongest of the hip flexors (rectus femoris, sartorius, and tensor fasciae latae), iliopsoas is important for standing, walking, and running.

It is, however, a typical posture muscle dominated by slow-twitch red type 1 fibers, and is therefore 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.

Owing to its proximal attachments, a pus-filled abscess, as may occur in lumbar tuberculosis, may drain inferiorly into the upper medial thigh and present as a swelling in the region.

See also

• Iliopsoas tendinitis
• Muscles of the hip

References

• 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 3-13-1420511-2. {{cite book}}: Check |isbn= value: length (help) (ISBN for the Americas 1-58890-419-9)

External links

• Template:Exrx
• UCC
• Cross section image: pelvis/pelvis-e12-15—Plastination Laboratory at the Medical University of Vienna