Lip

The lip (also spelled Farruur in Somali) is one of two fleshy parts forming the border of the mouth opening. There is an upper lip and a lower lip. They consist of skin, muscle, and sensory tissue on the inner surface.

The lips play a role in eating, drinking, articulating words, and facial expression. They are also a site of acute tactile sensation due to the high concentration of sensory nerve endings.

Structure

The most important muscle of the lip is the orbicularis oris, which encircles the mouth. When contracted, it closes or protrudes the mouth. Other facial muscles connect to the upper and lower lips, causing frowning and other expressions.

The surface of the lip differs from other skin: it is thin, hairless, and lacks sweat glands, with its color derived from small blood vessels visible beneath. Because of its thin epidermis, the lips dry out quickly in dry air or low humidity conditions.

Speech function

Certain sounds depend directly on the lips. In Somali, the consonants 'b', 'm', and 'f' require the lips to meet or touch the upper teeth. For this reason, changes in the lip can affect speech articulation.

Health conditions

The lip can be affected by cleft lip, a congenital defect treated surgically; inflammation of the lip from viral infection or vitamin deficiency; and viral infection. Additionally, because it receives direct sun exposure, the lower lip carries a risk of oral cancer.