Lip

Lip

The lip is a visible body part at the mouth of many animals, including humans. 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 an erogenous zone when used in kissing and other acts of intimacy.

Structure

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.

Upper lip

The upper lip, also called the labrum, is separated from the nose by the philtrum. The philtrum is the vertical groove in the middle area of the upper lip, common to many mammals, extending in humans from the nasal septum to the tubercle of the upper lip. Together with the lower lip, it defines the mouth area.

Lower lip

The lower lip, also known as the labium inferius, is the lowermost part of the mouth and is highly sensitive to touch. The lower lip covers the anterior body of the mandible. It is lowered by the depressor labii inferioris muscle and the orbicularis oris borders it inferiorly.

Function

Lips play a crucial role in a variety of physical functions, from the articulation of sound for speech to eating and drinking. They are also a tactile sensory organ, and can be an erogenous zone when used in kissing and other acts of intimacy.

Clinical significance

Various health conditions and habits can have an impact on the appearance and feel of the lips. For example, lips can develop visible cracks and fissures, a symptom often caused by a dry or cold climate, dehydration, overexposure to the sun, or habitual licking of the lips. Certain diseases can also manifest symptoms on the lips, including oral herpes and hand, foot, and mouth disease.

See also

• Cheilitis
• Cleft lip
• Lip augmentation
• Lip piercing
• Lip balm
• Lip gloss
• Lip liner
• Lipstick

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