Breaking down a sequence: line of action in the face

Today I wanted to go deeper into facial animation, especially about the line of action in the face.

Whenever you see someone standing you can notice that he has a natural posture that shows a counterpose between the hips and the shoulders (and the head too for balance).
From the most popular statues and paintings from the renaissance artists, to the last illustrations or cartoons of nowadays, you can clearly see it.

You can apply the same structure to the face, making one side stretched, while the other side is squashed.

I framed through a sequence from Brave (the best one of the entire movie in my personal opinion), and it's full of examples of this principle:

As you can see, in this shot even though he's changing expression, she's keeping the same line of action in the face.
This structure is more obvious in Merida's face:

Merida's a young girl, full of energy, and because of this she's moving faster than her mother, especially in this shot.

You can see all of that in her abrupt changes of body, but also in her quick movements of the entire head.

As you can see her face is squashing and stretching in relation to her body: when her hips go up her face first stretches, then catches up the movement, squashes and regain its shape.

Of course the same approach was first made in 2D animated movies.

I've taken a random frame from Treasure Planet, and here's what I found: