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Iliopsoas Muscle

Introduction

The term “iliopsoas muscle” is used to describe one functional unit composed of two muscles; the iliacus muscle and the psoas major muscle, both acting together as the major flexor muscles of the hip.

In this tutorial, we will look at the origin, insertion, innervation, and action of both of image descriptionthese muscles.

An illustration showing an anterior view of the hip girdle muscles and the Iliopsoas muscle is highlighted with green
An illustration showing an anterior view of the hip girdle muscles and the Iliopsoas muscle is labeled and highlighted with green
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Iliacus muscle

Attachments

Origin (proximal attachment):

Iliac fossa of the hip bone (Os Coxae).

Insertion (distal attachment):

image descriptionLesser trochanter of femur.

The anterior view of the thigh, pelvis and lower section of the vertebral column. The only visible labelled muscle is Iliacus.
Anterior view of the thigh, pelvis and lower section of the vertebral column showing the origin of Iliacus at the iliac fossa of os coxa and the insertion at the lesser trochanter of femur.
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Innervation

Femoral nerve (L2-L3).

Psoas muscle

Attachments

 Origin (proximal) attachments:

Vertebral bodies and transverse processes of T12-L4, Intervertebral discs between T12-L4, Costal processes of L1-L5 vertebrae.

Insertion (distal) attachments:

It forms a strong tendon with the Iliacus muscle, inserting into the image descriptionlesser trochanter of femur.

The anterior view of the thigh, pelvis and lower section of the vertebral column. The only visible labelled muscle is Psoas Major.
An anterior view of the thigh and pelvis showing the origin and attachment of Psoas Major muscle.
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Innervation

Anterior (ventral) rami of lumbar plexus (L1-L3).

Action of Iliopsoas

Slide 1 of the animation showing flexion of the thigh.
Slide 2 of the animation showing flexion of the thigh.
Slide 3 of the animation showing flexion of the thigh.
Slide 4 of the animation showing flexion of the thigh.
Slide 5 of the animation showing flexion of the thigh.
Thigh flexion
Slide 1 of the animation showing lateral rotation of the thigh.
Slide 2 of the animation showing lateral rotation of the thigh.
Slide 3 of the animation showing lateral rotation of the thigh.
Slide 4 of the animation showing lateral rotation of the thigh.
Slide 5 of the animation showing lateral rotation of the thigh.
Thigh rotation

Furthermore, the iliopsoas muscle is an important postural muscle, helping in standing, walking, and running.

Test yourself

A quiz image of the anterior view of the thigh, pelvis and lower section of the vertebral column. The muscles of the anterior thigh are numbered 1 to 9 and the answers are concealed.
A quiz image of the anterior view of the thigh, pelvis and lower section of the vertebral column. The muscles of the anterior thigh are numbered 1 to 9. The answers revealed at the bottom are as follows 1. Psoas Major 2. Iliacus 3. Tensor Fasciae Latae 4. Pectineus 5. Adductor Longus 6. Rectus Femoris 7. Vastus Lateralis 8. Sartorius 9. Gracilis.
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