<P> All four quadriceps are powerful extensors of the knee joint . They are crucial in walking , running , jumping and squatting . Because rectus femoris attaches to the ilium , it is also a flexor of the hip . This action is also crucial to walking or running as it swings the leg forward into the ensuing step . The quadriceps , specifically the vastus medialis , play the important role of stabilizing the patella and the knee joint during gait . </P>
what is the principle action of the vastus lateralis and the other quadriceps muscles
crucial in walking , running , jumping and squatting