The Full Posture Comes with Work
Looks cool, doesn't it? But this isn't the whole picture.
The truth is I was limited on time and quickly took this photo without a warm up. Not so good for me, since I strained my shoulders. Good for you because my body highlighted all the muscles I should have warmed up first, giving me a nice road map for a teaching.
No posture stands on its own. There is whole practice leading up to this pose working different body parts - hips, quads, shoulders, to name a few. I took my time in my next practice to work those body parts outlining a a strong, safe Upward Facing Bow class for you.
When you see a full posture keep in mind there was a whole practice behind it.