[Phylogenetic aspects of lip function].

Lips can be considered a phylogenic summary of nasolabial and facial muscle evolution. They represent the central point of facial morphogenesis. The progressive development of oral and facial functions is an elementary human necessity for feeding, suction, oral competence, swallowing, language, and mimics. Each discontinuity causes functional and anatomic disorders. Any damage to the lips creates facial unbalance. Precise knowledge of lip function is indispensable for optimal reconstruction.