Skip to main content

Unfortunately we don't fully support your browser. If you have the option to, please upgrade to a newer version or use Mozilla Firefox, Microsoft Edge, Google Chrome, or Safari 14 or newer. If you are unable to, and need support, please send us your feedback.

Publish with us
Iliacus Muscle
Muscular System

Iliacus Muscle

Musculus iliacus

Read more

Quick Facts

Origin: Iliac crest; superior two thirds of iliac fossa; ala of sacrum; anterior sacroiliac ligaments.

Insertion: Lesser trochanter of femur, via tendon of psoas major.

Action: Flexes thigh at hip joint; flexes trunk.

Innervation: Femoral nerve (L2-L3).

Arterial Supply: Iliac branch of Iliolumbar artery, deep circumflex iliac, obturator, and femoral arteries.

Complete Anatomy
The world's most advanced 3D anatomy platform
Try it for Free
Related parts of the anatomy


The iliacus muscle originates from the:

- inner lip of iliac crest;

- superior two thirds of the iliac fossa;

- ala of sacrum;

- anterior sacroiliac ligaments.


The fibers of the iliacus muscle travel anteroinferiorly and insert onto the tendon of the psoas major, which inserts onto the lesser trochanter of the femur.

Key Features & Anatomical Relations

The iliacus muscle is one of the two muscles that form the iliopsoas muscle, the other being the psoas major muscle. It is a large, broad, convergent type of skeletal muscle. Within the greater pelvis, the fibers of the iliacus muscle converge as they travel anteroinferiorly towards the inguinal ligament. After it passes deep to the lateral one third of the inguinal ligament, the iliacus muscle travels inferiorly within the anterior compartment of thigh towards its insertion site.

The iliacus muscle is located:

- anterior to the capsule of the hip joint and the iliopectineal bursa;

- posterior to the inguinal ligament;

- medial to the ilium and sartorius muscle;

- lateral to the psoas major muscle and the femoral and lateral femoral cutaneous nerves.

Actions & Testing

Overall, the iliopsoas muscle is involved in multiple actions:

- during unilateral contraction, it flexes the thigh at the hip joint;

- during bilateral contraction, it flexes the trunk.

The iliacus muscle cannot be tested in isolation, therefore both muscles of the iliopsoas are tested simultaneously by flexing the thigh at the hip joint against resistance while in the supine position with the knee flexed (Standring, 2016).

List of Clinical Correlates

- Iliopsoas tendinitis

- Thomas test


Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.

Learn more about this topic from other Elsevier products

Iliacus Muscle

ScienceDirect image

The iliacus muscle begins from the inner lip of the iliac crest, upper two thirds of the iliac fossa, and superolateral portion of the sacrum.

Explore on ScienceDirect(opens in new tab/window)

Complete Anatomy

The world's most advanced 3D anatomy platform

Complete Anatomy