Q:

Difference between cranio and teschio

I am studying the difference between "cranio m" and "teschio m" (the m stands for masculine).
Hypothesis number one: "cranio m" refers to set of bones of a person that is alive; "teschio m" is a symbol of skull, "teschio m" can be used to refer to a pirate flag.
Hypothesis number two: "cranio m" refers to a skull of a person that is alive or dead, if still has human tissue other than bones. "Teschio m" is used to refer to a skull of a person that has no other human tissue but the bones.
Am I right?
Thank you.

A:

A famous passage from Rosmunda by Vittorio Alfieri

ROSMUNDA. [...]
  Nol vegg'io sempre, a quella orribil cena
  (banchetto a me di morte) ebro d'orgoglio,
  d'ira, e di sangue, a mensa infame assiso,
  ir motteggiando? e di vivande e vino
  carco, nol veggio (ahi fera orrida vista!)
  bere a sorsi lentissimi nel teschio
  dell'ucciso mio padre? indi inviarmi
  d'abborrita bevanda ridondante
  l'orrida tazza? E negli orecchi sempre
  quel sanguinoso derisor suo invito
  a me non suona? Empio ei dicea: «Col padre bevi,
  Rosmunda». [...]

The phrase “Bevi Rosmunda dal teschio di tuo padre” is commonly associated to it, coming from a parody by Achille Campanile of Alfieri's tragedy (see Wikipedia). This should make clear that teschio is not just a symbol.
According to the Treccani dictionary the word is used to denote the bones of the head, almost exclusively for dead bodies of human beings or animals. It comes from Latin testulum (pottery vase), like testa (head) comes from testum.
The word cranio refers to the anatomic part and can be used both for living and dead bodies.

