!Muscles
The chart above is from Wikipedia,
> **It is difficult to determine exactly how many muscles are involved in smiling or frowning as there is a wide range of facial expressions that might be considered a frown or a smile**.
which sources The Straight Dope,
> **Deciding which of the 53 facial muscles are important in smiling or frowning is a bit arbitrary** \--many make only minor contributions, and depending on the intensity of the expression may not be involved at all.
who got it from **plastic surgeon and professor at the University of Chicago HospitalsDavid H. Song.**
> * Grand total for smiling: 12
>
> * Grand total for frowning: 11
>
>
**More:**
* Snopes - Happiness Is Only Grin Deep
* Discovery Health - How many muscles does it take to smile?