Four According to Wikipedia: The quadriceps femoris (quadriceps, quadriceps extensor, guads or quads) includes the four prevailing muscles on the front of the thigh. It is the great extensor muscle...
depends on how much muscle mass you have ;)
the body has 630 muscles
more than 600 muscles in your body
600
How to Make an Exercise Plan - Quadricep Workout Cool Down Stretches
How to Make an Exercise Plan - Quadricep Workout Using a BOSU Ball
How to Make an Exercise Plan - Quadricep Workout Through Squats
How to Make an Exercise Plan - Quadricep Workout with a Resistance Ball