Iliacus muscle

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 iliac spine and anterior inferior iliac spine, and the notch between them.

The fibers converge to be inserted into the lateral side of the tendon of the Psoas major, which contributes to flexing the femur anteriorly onto the pelvis. Some of the iliacus fibers may reach the body of the femur, for about 2.5 cm. below and in front of the lesser trochanter.

The Iliacus is sometimes considered a part of the Iliopsoas group of hip flexor muscles.

This muscle is innervated by the anterior branches of the Femoral nerve (anterior branches of L2-3).