Trigger point · Lumbar spine

Psoas major

The hip flexor that produces back pain, and produces it in a shape worth recognising: a VERTICAL stripe down the low back on the same side, from around the bottom of the ribs toward the sacrum — vertical where almost every other back referral runs across or on a slant. It also refers to the front of the thigh and the groin, so one muscle can put pain in the back and the front of a person at once. The tell is the behaviour as much as the map: this pain is typically worse standing and walking and eased by sitting or lying with the hip bent — the opposite of what people expect from a back — because flexing the hip is what takes the muscle off tension. The point lies deep, in a belly that runs down the back of the abdomen over the brim of the pelvis, so it is neither what the client points to nor what most back treatment reaches. That is exactly why a low back that will not settle is worth asking the front of the body about.