The psoas is a deep muscle located in the lower back and pelvis. It plays a crucial role in connecting the spine to the legs, allowing for movements such as bending and lifting the knees. The psoas is often referred to as a hip flexor, as it helps flex the hip joint and stabilize the spine during various activities. This muscle is essential for maintaining good posture and balance. Tightness or weakness in the psoas can lead to discomfort and issues in the lower back and hips. Regular stretching and strengthening exercises can help keep the psoas healthy and functional.