Q: My upper back is very tight and starting to feel painful. I am careful to draw my shoulder blades onto my back but not to pinch them. Then I broaden, expanding just below the shoulder blades. Thoughts?
A: My thoughts on the blades is that you may be overusing the rhomboids and trapezius to draw the blades closer together. To open this area back up, I'd recommend Eagle Pose. There's so much focus in opening the chest, which is great and really helps posture, but anything can be overdone.
Next, to keep the shoulder blades "on the back" and prevent winging, use the serratus anterior. Here are some suggestions on finding this muscle:
1. Come on all fours into a Table Top position. Push through your hands and notice how the spine between the blades lifts and the blades move laterally. Now sink down (even collapse if you don't have a shoulder injury) and see how the blades come closer together. Explore back and forth a few times and then find the point where your shoulders feel engaged (as in the pushing version), yet the spine is not lifting. Doug Keller calls these "serratus pushups."
2. Stand facing a wall and place your right hand under the left arm pit so you can feet the side upper ribs. Bend the left elbow (pointing slightly towards the floor) and bring the left hand about a foot in front of the left shoulder, palm on the wall. Without moving the torso, push into the wall. Under your right hand you'll feel the serratus working. Bring focus to the muscle throughout a practice and see if you're using it. To strengthen even more, do push ups at the wall focusing on the serratus staying engaged and the mid back soft.
3. Finally, experiment with Down Dog. Start in Table Top and find the balance from exercise 1, above. Keeping serratus engaged, come into down dog. Notice that it is impossible to fall into the shoulder joints if serratus stays active. Pretty interesting stuff.
As an aside, Susi Hately Aldous wrote a fascinating article at regarding inversion and the shoulders.