This is from when I was a lot younger doing pullups. I remember one side always being stronger and feeling uneven during my reps. Long since then I've worked on depressing the shoulders before rows and pullups but my left side just doesn't seem to want to even out. My lower lats are great and have equal width, I'm talking about right under the armpit. One side has quite a bit of width when flexed, but the other is basically non-existent. Is this muscle only targeted by doing wide grip pullups or what's the deal? Having these imbalances bugs me and I know not everyone is symmetrical. On the other hand I had this problem with my left rear deltoid and was able to fix it, so I know this can be fixed as well and was only a result of bad form in my earlier years.
So, what really targets the UPPER lat muscles?