Yes it does. The quadriceps (the muscles in front of your thigh) are the equivalent of your triceps in your upper arm, whereas the muscles in the back of your thigh (biceps femoris) correspond to the biceps in your upper arm. Therefore, when you flex your knee, the quadriceps flatten out over the thigh bone while the biceps femoris thickens the same way when you flex your arm. The quadriceps thicken and become more well defined when you actually extend your knee.