IS YOUR HIP PAIN COMING FROM A TIGHT PSOAS MUSCLE? The psoas muscle, (psoas major) is often a muscle that gets blame a lot for people who have both hip and back pain. Unfortunately it gets blamed way too much. The psoas major muscle is a fusiform muscle lateral to the lumbar region of the vertebral column and the pelvis. It attaches by slender fasciculi cranially to the medioventral surface of the vertebral body and disc, and caudally to the ventrocaudal borders of the lumbar transverse processe