The lips, also known as labia, form the entryway of the mouth. There are
2 different surfaces of the lip:
1.
Skin
2.
Mucous membrane (vermilion border and internal surface)
Underlying the
keratinized epithelium of the skin of the lips are the following structures:
Vasculature
Sweat glands
Hair follicles
Muscles that function to move the lips
The mucous membrane of the lips is non-keratinized with many capillary vessels close to the surface, giving it the pinkish/red color. Examination of the lips is valuable in recognizing signs of illness (eg,
Cyanosis: A bluish or purplish discoloration (as of skin) due to deficient oxygenation of the blood.
