Damage occurs to the collagen and elastin fibers in the reticular dermis over time. Expression lines are caused by a gradual “denting” of these fibers from repeated facial movements. Just like a piece of metal that is bent multiple times, the fibers become weaker and weaker and thinner in the area of the constant bend.
WHY DOES OUR SKIN LOSE ELASTICITY AND START TO SAG?
Our skin is tightened by a structure of collagen fibres in the dermis in a network of skin cells, fibres and blood capillaries. Below in the hypo-dermis or subcutaneous layer there is supporting fat tissue with strong and elastic collagen fibres, and the circulatory system.