The cycle continues as the mass vibrates back and forth about a fixed position. The springs inside of a bed mattress, the suspension systems of some cars, and bathroom scales all operated as a mass on a spring system. In all the vibrating systems just mentioned, damping is clearly evident.
[Continued from above] . . . Contraction of the quadriceps group extends the leg at the knee and flexes the thigh at the hip. The hamstring muscle group extends across the posterior surface of the thigh from the ischium of the pelvis to the tibia of the lower leg.
1 Vastus medialisâpart of the quadriceps femoris on the inside-front of the thigh, it extends or straightens the leg and is controlled by the femoral nerve. 2  Plays a part in stabilizing the knee cap.3  Rectus femorisâon the front middle of the thigh and covers the other three quad muscles. Vastus lateralisâpart of the quadriceps femoris on the outside-front of the thigh, it extends or straightens the leg and is controlled by the femoral nerve. 2  Vastus intermediusâpart of the quadriceps femoris on the center-front of the thigh, it extends or straightens the leg and is controlled by the femoral nerve.