(I) Postural Wrinkles:
These mainly appear on the neck. A normal person is born with multiple horizontal wrinkles on their neck. These wrinkles do not necessarily indicate aging, but as a person ages and the platysma muscle contracts over a long period, it can deepen the horizontal wrinkles and cause the skin between the wrinkles to become loose, symbolizing facial aging.
(II) Dynamic Wrinkles:
This type of wrinkle is the result of contraction of the facial expression muscles. Once they appear, they will not disappear even if the facial muscles are inactive. The location, time, and number of these wrinkles vary from person to person depending on individual facial expressions and habits.
1) Forehead Wrinkles: Appear in the middle of the forehead, running horizontally, and are the result of contraction of the frontalis muscle. This type of wrinkle appears relatively early, with some people beginning to see these wrinkles during their youth.
2) Frown Lines: Appear between the eyebrows, running vertically, and are the result of contraction of the corrugator supercilii muscles.
3) Eyelid Wrinkles: Appear on the upper and lower eyelids, often in large numbers. The wrinkles on the upper eyelid are finer, while those on the lower eyelid are coarser. Their direction is generally vertical or slightly inclined. There may also be tear troughs under the eyes, and these wrinkles are the result of orbicularis oculi muscle contraction.
4) Crow's Feet: Located at the outer corners of the eyes, arranged radially, varying in length and number from person to person. These wrinkles are also the result of orbicularis oculi muscle contraction.
5) Nasolabial Fold Wrinkles: Appear on the cheeks and are the result of contraction of the levator labii superioris and zygomaticus muscles.
6) Cheek Wrinkles: Appear on the cheeks and are the result of contraction of the levator labii superioris and zygomaticus muscles.