What type of facial marking is the mandibular sulcus classified as?

The mandibular sulcus is classified as an acquired facial marking. This marking develops as a result of various factors, including the natural aging process, the effects of gravity, and use of facial muscles over time. Acquired markings are distinct from inherited characteristics, which are genetically determined and present at birth, as well as from natural markings that may be more indicative of the original anatomical structure. While temporary markings can occur due to various transient factors, the mandibular sulcus is a semi-permanent feature that becomes more pronounced with age and doesn't simply disappear. Therefore, acquired facial markings, such as the mandibular sulcus, highlight changes that occur in the skin and underlying structures due to external and physiological influences rather than those that are innate.