Ans: All the muscles present in the quadriceps femoris tend to work together in order to extend or straighten the knee in the best way. Apart from that, the rectus femoris is responsible for the flexing of the hip. The vast medialis is responsible for adducting the thigh. It also externally and internally rotates the thigh. The vast medialis has a role to play in stabilizing the kneecap as well. Most of the quadriceps muscles remain primarily active during jumping, kicking, running, and cycling. These muscles help the person move freely from one place to another. In everyday life, the function of quadriceps muscles is to ensure that people are able to run and walk properly when they are going downhill.