Lip

Lips are a visible body part at the mouth of humans and many animals.

Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Human lips are a tactile sensory organ, and can be erogenous when used in kissing and other acts of intimacy.

Structure

The upper and lower lips are referred to as the "Labium superius oris" and "Labium inferius oris", respectively. The juncture where the lips meet the surrounding skin of the mouth area is the vermilion border, and the typically reddish area within the borders is called the vermilion zone. The vermilion border of the upper lip is known as the cupid's bow. The fleshy protuberance located in the center of the upper lip is a tubercle known by various terms including the procheilon (also spelled prochilon), the "tuberculum labii superioris", and the "labial tubercle". The vertical groove extending from the procheilon to the nasal septum is called the philtrum.

The skin of the lip, with three to five cellular layers, is very thin compared to typical face skin, which has up to 16 layers. With light skin color, the lip skin contains fewer melanocytes (cells which produce melanin pigment, which give skin its color). Because of this, the blood vessels appear through the skin of the lips, which leads to their notable red coloring. With darker skin color this effect is less prominent, as in this case the skin of the lips contains more melanin and thus is visually darker. The skin of the lip forms the border between the exterior skin of the face, and the interior mucous membrane of the inside of the mouth.

Lip (gastropod)

In the shell of gastropod mollusks (a snail shell), the lip is the free margin of the peristome (synonym: peritreme) or aperture (the opening) of the gastropod shell.

In dextral (right-handed) shells (most snail shells are right-handed), the right side or outer side of the aperture is known as the outer lip (labrum). The left side of the aperture is known as the inner lip or columellar lip (labium) if there is a pronounced lip there. In those species where there is no pronounced lip, the part of the body whorl that adjoins the aperture is known as the parietal wall.

The outer lip is usually thin and sharp in immature shells, and in some adults (e.g. the land snails Helicella and Bulimulus). However in some other land snails and in many marine species the outer lip is thickened, or reflected (turned outwards). In some other marine species it is curled inwards (inflected), as in the cowries such as Cypraea. It can also be expanded, as in Strombus; it can have finger-like processes (digitate) or it can be fringed with spines (foliated), as in Murex. The lip is called emarginate when it is incised or slit, as in Pleurotomaria. It is described as effuse when the basal or anterior extremity is slightly produced, depressed or reflected, as in Thiara. When the lip is bent into an "s" curve it is called sinuous, as is the case in the sigmoidal margin ofJanthina exigua.

Lip (disambiguation)

Lip (plural lips or labia) may refer to:

As a word

In entertainment