There's this spot that when I do tennis ball work is always a trigger point, sometimes lower in intensity and high in intensity when it's nagging me.
This spot is right where my lat, arm, and shoulder all meet together. The real trigger point fire breaks loose when I start internally and externally rotating my upper arm with the tennis ball in that spot.
After doing this it feels a lot better, but what is this spot? What's it function? What muscles and connective tissue are there? What will improve flexibility, mobility, and the strength of this area?