Psoas (soh-uhs) sounds like a terrible exotic disease that you could contract at the Summer Olympics, but it’s really just a muscle that can cause major back pain. The psoas is a deep lumbar/pelvic ...

What is a psoas and how do I know if I have one? If your upper body attaches to your lower body, chances are good you have at least two psoas muscles -- one psoas major muscle linking your spine to ...