The iliacus is a muscle of the posterior abdominal wall. It is a fan-shaped muscle that is situated inferiorly on the posterior abdominal wall. It combines with the psoas major muscle to form the iliopsoas – the major flexor of the thigh at the hip joint.
- Attachments: Originates from the surface of the iliac fossa and anterior inferior iliac spine. Its fibres combine with the tendon of the psoas major, inserting into the lesser trochanter of the femur.
- Actions: Flexion and lateral rotation of the thigh at the hip joint.
- Innervation: Femoral nerve (L2 – L4).
- Blood supply: Iliolumbar, deep circumflex iliac, obturator, and femoral arteries.