What are upper structure chords?
An upper structure is a chord that is built on a note other than the root of a chord. For example, if you play an F major triad and then add a D in the bass register, you have F/D (F major over D) which is the same thing as a D-7 chord.
What is upper chord?
Upper Structures are a nice sounding and simple way to voice altered dominant chords. They are simply a triad over a tritone. They always have a 3rd & 7th in the left hand (which is a tritone apart in a V7 chord) and some kind of triad in the right hand. ... They give a ready-made voicing for the chord.