If every muscle has a muscle antagonist as biceps/triceps,thus face muscls is one end fixing to the bones of scull,and other weaving in skin or mucus membrane.

 They are shortening,and for returning in back condition,they are needing relaxing.And excepting are chewing muscles,which beginning on the scull bones,attaching to the mobility jaw low and difference by force from an other mimic  muscles.

As many of peoples are not healthy.Different birth injures, bad bite, and habit to chew, sleep on one side,stress, harmful mimic habits are lead to muscle tone is destroy, and till weal, or hyper tone, and other are tension, squeeze, and hyper tone.

And thanks for hyper ans hypo tones are on our face and displaying nasolabial wrinkles, deep wrinkles, wings and other adult changes.As very visible is on thin faces with a thin layer of subcutaneous tissue.And very importance with face working is to understand a hyper tone or  hypo tone you  you are having a case.And if to stretch a weak muscle and remove a not excit spasm this is worsen problem, stretch zone and without a tone and needing in tone,that lead to a more hanging tissues. 

And if to try more stimulate spasming muscle ,thus lead to worsening of wrinkle.