5-Masseter- may go slack during fear
6-triangularis- muscle of sadness-- pulls down corners of mouth
7-corrugator- muscle of anguish, pulls eyebrows in and down towards nose
8-Buccinator- muscle of irony-- a deeper muscle that pulls the mouth straight back
9-platysma- a large sheet of muscle that attaches at the corners of the mouth, pulling down
This is just a partial list. The dozens of facial anatomy maps I've examined illustrate the facial musculature differently, many omitting minor muscles or calling them by different names.
Have patients Use your mirror or touch your face with your fingers and feel how each muscle moves and feels as you flex it with different amounts of tension.
Subliminal Smile Rehabilitation
Cancer patient counselor Yvonne White, takes an indirect approach when working with depressed or angry patients who don't want to smile. She assigns them exercises using muscles that are less obviously associated with the smile, like the platysma and mentalis muscles. She reports patients come back asking, "Are you trying to trick me into smiling? Because it's working."
Remember, facial muscles are but one category in the expression and experiencing of feelings. Posture, tone of voice, energy availability, previous activity all play important roles in what we feel and how we turn on our feelings.
Progressive Smile Activation