The Rectus Femoris muscle is a large muscle that makes up part of the quadriceps group. It functions to extend the knee and flex the hip. It originates on the anterior inferior iliac spine and part of the acetabulum. It’s insertion is the patella via the quadriceps tendon and tibial tuberosity via the patellar ligament. Trigger points in this muscle refer deep into the knee. This muscle is an often overlooked source of knee pain.