Are you sitting at a desk right now? Chances are your psoas muscles are contracted to hold you steady in an upright position with your hips in flexion. Say-what-as? The psoas, pronounced; “so-as,” are key muscles connecting the upper body with the lower body, and they directly link the spine to the legs. Hidden deep in the abdomen, these muscles are anything but invisible. They have an enormous influence on the body, especially the lower back. There are even books written and courses about the psoas! Here is the “simple” version, although they are anything but simple.
Located on either side of the spine, they originate from: the last thoracic vertebrae, all five lumbar vertebrae, and the neighboring intervertebral discs. They then merge with another muscle on the inside of the pelvis called the iliacus to form the iliopsoas and then attach to the lesser trochanter of the inner femur bone. The psoas primary action is to flex the hip joint or bring the knee to the chest, and also independently they assist in bending the torso side to side.