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.
Where the Deep Six Hip Muscles Are. The deep six get their name because they are deep inside the hip, under more famous butt muscle, the gluteous maximus. They all attach to the inside of the inside of the greater trochanter which is the bulb at the top of your thigh bone that goes into the the hip socket. They fan out to different locations around the low pelvis. The deep six hip muscles are, from top of the fan to bottom: piriformis. gemellus superior.