This question is something of a follow-on to my earlier question about personal pronouns and body parts. I think that I have seen sentences along the lines of both,
Der Arm tut mir weh.
Mein Arm tut weh.
I have developed the impression that the dative object is typically used when a definite article precedes the name of the body part, and less likely to be used when a possessive pronoun precedes the body part, as in the two example sentences above. However, www.duden.de gives the example
Mein/der Kopf, Bauch tut mir weh.
which somewhat contradicts my impression. Nonetheless ... is my impression correct? Is the Duden example slightly abberant in suggesting both mein and mir in the same sentence? Do the initial two example sentences convey the same meaning, or is there a difference of emphasis between them?