bnetta -- those guy name dials are full body morphs, they don't affect a specific muscle group.
I asked the same thing, because spinning a dial called "Fred" means nothing to me -- spinning a dial called "Asian" gives me a hint of what I can expect.
It annoys the crap out of me, actually, because I haven't a clue what they look like, what they do, what they morph. Which means I don't usually use them at all.
To me those are simply totally useless dials, because of the way they are named.
There is no muscle pack for M4 yet, and the M3 muscle pack has proper muscle names on the dials. Like, Pectoral.

Silke