the shoulders counter oscillate and counter undulate so the shoulders go back forward and backward and up and down just pay attention to this next time you're out for a walk you can feel your hips going backwards and forwards and also going up and down if it didn't go up and down you'd trip yourself every step and the shoulders do the same and then you have a spine which is this column of a bunch of different pieces that connects the shoulder to the pelvis which also rotates side bends and flexes and extends the whole system is this big torsional system this crossbody system