The iliacus is a flat, triangular muscle located in the lower abdomen, specifically in the pelvic region. It originates from the iliac fossa of the ilium, which is part of the hip bone, and it plays a crucial role in hip flexion. The iliacus works in conjunction with the psoas major muscle to form the iliopsoas, a major muscle group involved in movements such as walking and running. This muscle is innervated by the femoral nerve, which allows it to contract and facilitate movement. Strengthening the iliacus can improve overall hip function and stability, making it important for athletes and individuals engaged in physical activities. Proper flexibility and strength in the iliacus can help prevent injuries and enhance performance.