For the past six months I have been working on my pecs using seated cable fly and machine fly. With the seated cable fly I push downward slightly on the cables to isolate the pecs from the delts. So far things have been very good, the pecs are growing nicely.

Question: Is there such a thing as lower and upper pecs? If so, what are some ways to work the upper pecs without involving the delts and lats?

I know that the machine fly takes it partly there as it covers the pec entirely. But is there something to isolate the upper pecs?

All the research I've done suggests there is no such thing as lower, middle and upper pecs. Does anyone have any bodybuilding experience on this?