The hip flexors are a group of muscles located in the upper part of the leg, near the pelvis. These muscles include the iliopsoas (a deep muscle that extends from the lower back to the inside of the thigh), rectus femoris (one of the quadriceps muscles), and sartorius (another large muscle in the upper leg). The primary function of these muscles is to flex the hip, which means bringing the thigh towards the body. They also help with other movements such as walking or running. When these muscles are strong and healthy, they can support proper posture and balance while reducing the risk of injury.