The quadriceps (quads) is made up of four muscles on the front of the thigh. They all share the tendon that encloses the kneecap (the patella tendon), which attaches to the top of the shin.
The quadriceps /thigh muscles main function is to extend your lower leg (bring forward) especially in exercises such as sprinting.
Its important to always warm-up the muscles prior to exercise, so some simple cycling on a light resistance will encourage blood flow through the thigh muscles, which will assist with stretching.
There are a number of different exercises to work the lower body muscles, with the most popular being the Squat.
For persons looking at exercising for weight management, then performing exercises such as the squat will greatly aid any weight loss program.
The general rule for performing squats is never to let your knees travel over your toes - so if you look down at your feet in the lowering phase, you should always be able to see your toes.