Quadriceps

The quadriceps are the muscles at the front of the upper leg. They straighten the leg at the knee, and flex the leg forward at the hip.

The quads are the most powerful muscles of your body, so they can withstand heavy training. As the name suggests, there are 4 main muscles of the quads:

Rectus Femoris

This is the onely quad muscle to straddle the top of the femur (the upper leg bone) as its origin is at the front of the ilium (pelvic bone). It inserts into the patella (knee-cap) and the top front of the tibia (one of the bones of the lower leg). So this muscle both straightens the leg at the knee, and flexes the leg forward at the hip. A very important muscle in walking, running and kicking. It's the central muscle of the quads.

Vastus Lateralis

This muscle originates at the top of the femur (lateral side), and inserts at the patella and top front of tibia. It extends the leg at the knee. The vastus lateralis is at the outside of the front of the thigh. This gives the quad muscles a wide appearance - see the pic on the right.

Vastus Medialis

Originates at the top of the femur (medial side), and inserts at the patella and top front of tibia. It extends the leg at the knee, and is located at the inside of the front of the thigh.

Vastus Intermedius

This muscle originates at the upper 2/3 of the femur, and inserts at the patella and top front of tibia.

Best exercises for the Quads

Barbell Squats - the king of leg exercises - make sure you use correct technique to prevent injury. Have someone to spot you from behind if you go heavy.

Leg press machine - vary the width of your feet, wider feet targets the outer quads (vastus lateralis) and close feet target the inner quads (vastus medialis), while feet normal width apart targets the whole of the quads.

Seated Leg Extension machine

Lunges with barbell or dumbbells