Well the secret is a powerful exercise that was used by the legendary Steve Reeves to carve out a truly thick set of upper pecs that all his competitors were jealous of. (chestsculpting.com)
So you work upper pec when you do an incline type motion, now lets look at what happens when you do a neutral motion like a bench press or a downward angle like in a decline press. (scoobysworkshop.com)
The upper chest / upper pec area just below the collar bones can be one of the toughest areas of the body to fully develop. (hardgainermusclebuilding.com)