The lower-lip is also known as the inferior lip.
It is the lip closest to the chin (as opposed to closest to the nose).
The lower lip is just one of the structures in the human oral cavity. See also the links to pages about other parts of the mouth.
The topics of digestion and teeth are included in some school e.g. GCSE and/or A-Level courses in subjects such as biology and human biology and in other courses that include human anatomy & physiology, diet, nutrition, and other health sciences.