Origin: Iliac fossa
Insertion: Lesser trochanter of femur
Artery: Medial femoral circumflex artery, Iliolumbar artery
Nerve: Femoral nerve (L2, L3)
Action: Flexes and rotates laterally thigh
Antagonist: Gluteus maximus
The Iliacus is a flat, triangular muscle, which fills the iliac fossa. It arises from the upper two-thirds of this fossa, and from the inner lip of the iliac crest; behind, from the anterior sacroiliac and the iliolumbar ligaments, and base of the sacrum; in front, it reaches as far as the anterior superior and anterior inferior iliac spines, and the notch between them. The fibers converge to be inserted into the lateral side of the tendon of the Psoas major, some of them being prolonged on to the body of the femur for about 2.5 cm. below and in front of the lesser trochanter.