Scapular Plane coming in for a landing...PO Day 52

I don't like to use medical terms that are not transparent so I have been trying to find a simple explanation for " scapular plane." Unsuccessfully. So here's how I understand it.

The shoulder blades ( the scapula) aren't totally flat as they curve across your upper back. The distal ends curve forward about 30  degrees which is what gives us a slightly rounded upper shoulder  posture. Some people hunch their shoulders forward even more which leads to our moms saying"put your shoulders back and stand up straight."

If you extend your arm fully parallel to the floor and begin to move it backward, a comfortable angle is reached somewhere before your arm is at a 90 degree angle to the front midline of your body. That is probably the 30 degree point that you don't want to challenge with your operated shoulder.

If you force your arm farther back you can displace the ball from the socket. Not a good thing to do. "The simple act of reaching behind to scratch the middle of your back or (for women) undoing a bra-strap can dislocate a reverse shoulder implant. This action places the arm in a position of extension, adduction (arm close to the body), and internal rotation."

Also, when just comfortably seated or lying down, you should keep a small pillow or rolled up towel under or behind your elbow and upper arm so your arm does not drop backward of your torso. That position moves the ball and socket apart which is undesirable.

I don't yet know when we can quit worrying about things like this but it seems like this scapular plane has us booked for a long flight!