The Psoas Major is a long muscle located in the lower back and pelvis. It connects the lumbar vertebrae to the femur, playing a crucial role in hip flexion and stabilizing the spine. This muscle is essential for movements such as walking, running, and sitting. In addition to its primary function, the Psoas Major is often referred to as a "core" muscle because it helps maintain posture and balance. Tightness or weakness in this muscle can lead to discomfort and affect overall mobility, making it important for physical health and fitness.