The Vastus lateralis ( or ), also called the vastus externus is the largest and most powerful part of the quadriceps femoris, a muscle in the thigh. It arises from a series of flat, broad tendons attached to the femur, and attaches to the outer border of the patella. It ultimately joins with the other muscles that make up the quadriceps in the quadriceps tendon, which travels over the knee to connect to the tibia.