What muscle draws the corners of the mouth back and out?

The risorius muscle is responsible for drawing the corners of the mouth back and out, which gives the face a broader expression often associated with smiling or grinning. This muscle is situated at the side of the mouth and helps facilitate movements that widen the mouth.

It is important to understand that while the zygomaticus muscle is involved in facial expressions such as smiling, its primary function is to pull the corners of the mouth upward rather than sideways. The orbicularis oris muscle encircles the mouth and is primarily responsible for actions such as puckering the lips, rather than moving the mouth corners back. The masseter muscle, on the other hand, is a major muscle used for chewing and does not contribute to facial expressions. Thus, the risorius is specifically tailored for the movement described in the question, making it the correct choice.