Vol. I: VII. On the Proportions and on the Movements of the Human Figure: 355.
The Da Vinci Notebooks
The movement of the torso (355-361).Observe the altered position of the shoulder in all the movements of the arm, going up and down, inwards and outwards, to the back and to the front, and also in circular movements and any others.
And do the same with reference to the neck, hands and feet and the breast above the lips &c