All the Medicis are descended from the same branch, that of Giovanni de' Medici, the first Gonfalonier of Florence, but who is not part of the adventures of the House of Medici. This Giovanni had two sons, one is Cosimo, the other, Lorenzo.

Cosimo is the forebear of the famous senior branch, the one we have been discussing up to now: Cosimo the Elder, Piero the Gouty, Lorenzo the Magnificent , Piero the Reprobate, etc.

With respect to the junior branch, Lorenzo also had descendants: Gianpietro, who then fathered Lorenzo and Giovanni, etc. The latter Giovanni would become the First Grand Duke of Tuscany.

All the Medici family's grandeur was generated by the senior branch, which died out after Lorenzo the Magnificent's grandson died without descendants. Its power was then passed on to the junior branch when they ceased using the title of "Primo" of Florence to take on the more glorious title of Grand Duke of Florence and, later, Grand Duke of Tuscany.

Lorenzo di Pierfrancesco de' Medici is from the junior branch which, historically, held the throne the longest. Members of this branch include Cosimo I as well as Catherine de Medicis, Marie de Medicis and so on.