Trigger points in the quadricep muscles are commonly the cause of hip, thigh and knee pain  The quadriceps is a large group of muscles, the most massive of the leg, located in the anterior (front) of the thigh. They originate from above the hip joint and extend to below the knee. The primary action of the quadriceps is to extend the knee joint, but in conjunction with a number of other muscles in the front of the hip, they are also associated with hip flexion. Rectus femoris is part of the quadriceps femoris, which also includes the...