From a Western point of view, it's through a complex neurological pathway involving cranial nerves and neurotransmitters possibly. From a Chinese point of view, it's through the holograms represented in the Microsystems of the face which directly stimulate the internal organs and activate classical channels which end or begin in the face. These are all theories however they are very difficult to prove or disprove.
Wrinkles and fine lines are reduced by improving facial tone and the production of collagen fibre which is stimulated by expert acupuncture needle precision.
Skin elasticity is improved by nourishing the blood of the liver and promoting facial blood and lymph circulation.
The cosmetic acupuncture affects facial contour and tone. Using the facial lifting and muscle toning techniques, invigorates Qi and blood circulation and directly stimulates the muscle proprioceptors at the origin and insertion of the muscle itself.