What do the upper back muscles do?
The latissimus dorsi, or lats, are the widest muscles of the back. They pull the arms down and back towards the body. The rhomboids, between the shoulder blades, pull the blades together. Together they power every pulling movement, from opening a heavy door to climbing.
How do you train your upper back?
Rows pull towards the body and work the middle of the back. Pulldowns and pull-ups pull from overhead and focus more on the lats. If you train your chest, train your back at least as often so pushing and pulling stay balanced.