Iliopsoas muscle

Last revised by Arlene Campos on 12 Jan 2024

The iliopsoas muscle is a large compound pelvic muscle composed of the psoas major and iliacus. The iliopsoas belongs to the anterior compartment of the pelvic muscles and is a muscle of the posterior abdominal wall. It found within the iliopsoas compartment and is an important muscle in locomotion and upright posture. 

The iliopsoas muscle has its origin at the fusion of the psoas major and iliacus muscles. This fusion occurs at the level of L5-S2, and the combined muscles pass from the pelvis to the thigh under the inguinal ligament.

The psoas major and iliacus muscles merge at the level of the hip joint capsule, forming a common/conjoint tendon for iliopsoas muscle and inserting into the lesser trochanter; some iliacus muscles fibers directly attach to the lesser trochanter rather than via the tendon 5. The iliopsoas bursa lies between the posterior aspect of the iliopsoas muscle/tendon and the anterior hip joint.

  • bifid iliopsoas tendon 5,6

    • separate tendons between the level of the femoral neck and the lesser trochanter

    • on MRI, can be seen as a high T1 signal cleft between two low signal tendons

The inferior portion of the iliopsoas tendon below the inguinal ligament forms a part of the floor of the femoral triangle.

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