These other notes form the upper structure of a chord which includes the 9th, 11th and 13th.
Adding extensions to chords help to get off the beaten tracks and provides some new harmonic colors to your playing (chord soloing, comping, and arrangement).
This lesson provides useful extended major 7th chord shapes to apply to your playing.
A new printable PDF eBook is available. It's about 11 blues progressions for jazz guitar with tabs, analysis (with roman numerals), explanations and audio files, divided into four chapters :
1- Blues progressions and variations
2- Chord studies
3- Guitar walking-bass studies
4 -Rhythm patterns