The most common OVERLOADED, OVERWORKED shoulder muscle
Shoulder tip (probably one of the best tips ever in the history of tips I’ll make EVER!)
If you’re having shoulder pain, shoulder restriction in movement, the solution is often to release the knots in subscapularis. This is the muscle under the shoulder blade. Most people have compressed their shoulder joint via over internally rotated shoulder joint. Here is a trick I do to myself as my old mate @valeruan is not around to help me.
Watch both clips and you will get a good idea of the process and watch the second clip so you can see where the muscle in question is.