You're probably wondering what I'm doing in this picture, right? I'm checking for tight hip flexors.
"You're checking for tight hip flexors using the arms?" you might be asking.
Yep, the iliopsoas--composed of iliacus, psoas major, and psoas minor--connects the femur (your thigh bone) to your pelvis and lumbar spine (low back bones). Here's a picture from the Atlas of Human Anatomy.