I recently had the opportunity to take a Kripalu yoga class and was struck by an instruction that was given by the teacher for Downward Dog. She suggested broadening or abducting the scapula! In my experience most teachers have instructed me to adduct or stabilize the scapula on the back in Down Dog and Plank. But having tried this new approach, I find it works for me and allows the back to expand, giving more support and strength in this pose. What I have begun doing is to broaden the upper scapula while bringing the lower points of the scapulae together in Down Dog and Cat and it seems to do the trick. I was also instructed to align the wrist creases parallel to the front of the mat, bending the elbows, with the eyes of the elbows facing each other for hyper-extended or sensitive elbows, such as I have. After having experimented with many different arms, hand and bent elbow
positions in Cat and Down Dog and yet not finding a sense of “sama sthiti” up until now, I am amazed and pleased to find this positioning, combined with scapula abduction is working for me.
Abduction the scapula is done by the power of the serratus anterior. If this muscle is strong it can indeed stabilize shoulder girdle. Dog can be done with either instruction though as you point out adduction the scapula is more common instruction. Namaste Mukunda