|Artery||inferior labial, superior labial|
|Vein||inferior labial, superior labial|
Lips are a visible organ, at the mouth of humans and many animals. Lips are soft, protruding, movable, and serve as the opening for food intake, as an erogenous organ used in kissing and other acts of intimacy, as a tactile sensory organ, and in the articulation of speech.
One differentiates between the Upper (Labium superius) and lower lip (Labium inferius). The lower lip is usually somewhat larger. The border between the lips and the surrounding skin is referred to as the vermilion border, or simply the vermilion. The vertical groove on the upper lip, is known as the philtrum. The philtrum ( Greek philtron (φιλτρον from philein (φιλειν "to love to kiss" also known as the infranasal depression The entire skin between the upper lip and the nose is referred to as the "ergotrid".
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 less melanocytes (cells which produce melanin pigment , which give skin its color). Melanocytes are cells located in the bottom layer (the Stratum basale) of the skin's epidermis and in the middle layer of the eye (the Uvea) For the drug referred to as "pigment" see Black tar heroin. Because of this, the blood vessels appear through the skin of the lips, which leads to their notable red coloring. The blood vessels are part of the Circulatory system and function to transport Blood throughout the body 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 thicker.
The lip skin is not hairy, and does not have sweat glands or sebaceous glands. The skin contains two different groups of sweat glands: Apocrine sweat glands and Merocrine sweat glands. The sebaceous glands are Glands found in the Skin of Mammals Locations and morphology A branched type of Acinar gland, these Therefore it does not have the usual protection layer of sweat and body oils which keep the skin smooth, inhibit pathogens, and regulate warmth. For these reasons, the lips dry out faster and become chapped more easily.
The skin of the lips is stratified squamous epithelium. The skin is the outer covering of living tissue of an animal (or plant In Anatomy, squamous epithelium (from Latin squama, "scale" is an Epithelium characterised by its most superficial layer consisting The mucous membrane is represented by a large area in the sensory cortex, and is therefore highly sensitive. The Frenulum Labii Inferioris is the frenulum of the lower lip. The Frenulum Labii Superioris is the frenulum of the upper lip.
The facial artery is one of the six non-terminal branches of the external carotid artery. The facial artery ( external maxillary artery in older texts is a branch of the External carotid artery that supplies structures of the face In Human anatomy, the external carotid artery is a major Artery of the head and neck It supplies the lips by its superior and inferior labial branches, each of which bifurcate and anastomose with their companion artery from the other side.
The muscles acting on the lips are considered part of the muscles of facial expression. A facial expression results from one or more motions or positions of the Muscles of the Face. All muscles of facial expression are derived from the mesoderm of the second pharyngeal arch, and are therefore supplied (motor supply) by the nerve of the second pharyngeal arch, the facial nerve (7th cranial nerve). A germ layer is a collection of cells formed during animal Embryogenesis. In the development of vertebrate animals, the pharyngeal arches (also called branchial arches or gill arches in fish develop during the fourth The facial nerve is the seventh (VII of twelve paired Cranial nerves. Cranial nerves are Nerves that emerge directly from the Brain stem in contrast to Spinal nerves which emerge from segments of the Spinal cord. The muscles of facial expression are all specialised members, of the panniculus carnosus, which attach to the dermis and so wrinkle, or dimple the overlying skin. The panniculus carnosus is part of the Subcutaneous tissue It consists of sheets of flat muscle contained in the Panniculus adiposus. The dermis is a layer of Skin beneath the epidermis that consists of Connective tissue, and cushions the body from stress and strain Functionally, the muscles of facial expression are arranged in groups around the orbits, nose and mouth. In Anatomy, the orbital bone is the cavity or socket of the Skull in which the Eye and its appendages are situated Anatomically a nose is a protuberance in Vertebrates that houses the Nostrils or nares which admit and expel air for respiration in conjunction with the The mouth, buccal cavity, or oral cavity is the first portion of the Alimentary canal that receives food and begins digestion by mechanically breaking up
The muscles acting on the lips:
Because they have their own muscles and bordering muscles, the lips are very movable. A sphincter is a structure usually a circular Muscle, that normally maintains constriction of a natural body passage or orifice and which relaxes as required by normal physiological The buccinator is a thin quadrilateral muscle occupying the interval between the Maxilla and the Mandible at the side of the face In Human anatomy, the orbicularis oris muscle is the Sphincter muscle around the Mouth. In facial anatomy the modiolus is a Chiasma of facial muscles held together by fibrous tissue located lateral and slightly superior to each angle of the mouth The levator labii superioris (or quadratus labii superioris) is a broad sheet the origin of which extends from the side of the Nose to the Zygomatic bone The levator labii superioris alaeque nasi muscle is translated from Latin, the "lifter of the Upper lip and of the Wing of the nose The levator anguli oris ( caninus) is a facial Muscle of the Mouth arising from the Canine fossa, immediately below the Infraorbital The zygomaticus minor is a Muscle of facial expression It originates on the Zygomatic bone and then inserts on the upper lip The Zygomatic major is a Muscle of the Human body. It is a Muscle of facial expression which draws the angle of the mouth superiorly and posteriorly The risorius arises in the fascia over the Parotid gland and passing horizontally forward superficial to the Platysma, inserts onto the skin at the angle of the The Depressor anguli oris ( Triangularis) arises from the oblique line of the Mandible, whence its fibers converge to be inserted by a narrow fasciculus into the The depressor labii inferioris (or quadratus labii inferioris) is a Facial muscle that helps lower the Bottom lip. The Mentalis is situated at the tip of the Chin. It raises and pushes up the lower lip causing wrinkling of the chin as in doubt or displeasure Lips are used for eating functions, like holding food or to get it in the mouth. In addition, lips serve to close the mouth airtight shut, and to, hold food and drink inside, and to keep out unwanted objects. Through making a narrow funnel with the lips, the suction of the mouth is increased. This suction is essential for babies to breast feed. Breastfeeding is the feeding of an Infant or young Child with Breast milk directly from human Breasts, not from a Baby bottle or other Lips can also be used to suck in other contexts, such as tactile stimulation of other people.
Because of their high amounts of nerve endings, the lips are an erogenous zone. An erogenous zone is an area of the Human body that has heightened Sensitivity and stimulation of which normally results in sexual response. The lips therefore play a crucial role in kissing and other acts of intimacy. A kiss is the touching of one person's lips to another place which is used as an expression of Affection, Respect, Greeting, Farewell As the mouth, lips, and tongue are among a woman's most erogenous zones, stimulating a woman's mouth and lips during acts of intimacy has been shown to elicit pleasure and to have a direct stimulatory effect on arousing her genital organs. 
A woman's lips are also a visible expression of her fertility. In studies performed on the science of human attraction, psychologists have concluded that a woman's facial and sexual attractiveness is closely linked to the makeup of her hormones during puberty and development. Contrary to the effects of testosterone on a man's facial structure, the effects of a woman's estrogen levels serve to maintain a relatively "childlike" and youthful facial structure during puberty and during final maturation. Testosterone is a Steroid hormone from the Androgen group In mammals testosterone is primarily secreted in the testes of males and the Ovaries Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle, It has been shown that the more estrogen a woman has, the larger her eyes and the fuller her lips. Surveys performed by sexual psychologists have also found that universally, men find a woman's full lips to be more sexually attractive than lips that are less so.  A woman's lips are therefore sexually attractive to males because they serve as a biological indicator of a woman's health and fertility. As such, a woman's lipstick (or collagen lip enhancement) takes advantage by "tricking" men into thinking that a women has more estrogen than she actually has, and thus that she is more fertile and attractive. Collagen is the main Protein of Connective tissue in Animals and the most abundant protein in Mammals making up about 50% of the whole-body protein 
The lip has many nerve endings and reacts as part of the tactile (touch) senses. A nerve is an enclosed cable-like bundle of peripheral Axons (the long slender projections of Neurons. Lips are very sensitive to touch, warmth, and, cold. It is therefore an important aide for exploring unknown objects for babies and toddlers.
The lips serve for creating different sounds - mainly the labial, bilabial, and labiodental consonant sounds - and thus create an important part of the speech apparatus. Labials are consonants articulated either with both lips ( bilabial articulation or with the lower lip and the upper teeth ( labiodental articulation In Phonetics, a bilabial consonant is a Consonant articulated with both Lips The bilabial consonants identified by the International Phonetic Alphabet In Phonetics, labiodentals are Consonants articulated with the lower Lip and the upper Teeth. The lips enable whistling and the performing of wind instruments such as the trumpet, clarinet, and flute.
See Full Article: facial expression. A facial expression results from one or more motions or positions of the Muscles of the Face. The lips visibly express emotions.
Lips are often viewed as a symbol for sensuality and sexuality. This has many origins; above all, the lips are a very sensitive erogenous and tactile organ. Reproductive psychologists have suggested that one reason the female lips are seen as sexually attractive might be because they mimic the appearance and sexual swelling of the labia of the vulva, and that a woman's lips are effectively a secondary sexual organ.  This is consistent with research showing male sexual attitudes towards a woman's lips and mouth to be very similar to those towards a woman's vulva. Furthermore, in many cultures of the world, a woman's mouth and lips are veiled because of their representative association with the vulva, and because of their role as a woman's secondary sexual organ.
As part of the mouth, the lips are also associated with the symbolism associated with the mouth as orifice by which food is taken in. The lips are also linked symbolically to neonatal psychology(see for example oral stage of the psychology according to Sigmund Freud). The oral stage in Psychoanalysis is the term used by Sigmund Freud to describe his theory of child development during the first 18 months of life in which an Sigmund Freud (ˈziːkmʊnt ˈfʁɔʏt born Sigismund Shlomo Freud (May 6 1856 &ndash September 23 1939 was an Austrian Psychiatrist who founded
As an organ of the body, the lip can be a focus of disease or show symptoms of a disease:
The labial coronary arteries, etc. A kiss is the touching of one person's lips to another place which is used as an expression of Affection, Respect, Greeting, Farewell Lipstick is a cosmetic product containing pigments oils waxes and emollients that applies color and texture to the lips. Lip gloss is a cosmetic product used primarily to give lips a mildly glossy lustre and sometimes subtle color Lip balm or lip salve is a substance topically applied to the lips of the Mouth to relieve chapped or dry lips Angular cheilitis or Stomatitis A Lip piercing is a type of Body piercing which penetrate the lips or the area surrounding the lips A facial expression results from one or more motions or positions of the Muscles of the Face. Herpes simplex is a Viral disease caused by Herpes simplex viruses both herpes simplex virus 1 (HSV-1 and herpes simplex virus 2 (HSV-2 cause herpes simplex Chapped lips is a condition whereby the Lips become dry and possibly cracked Cupid's bow is a facial feature where the double curve of a human upper lip is said to resemble the bow of the Cupid, the Roman god of erotic love Cleft lip (cheiloschisis and cleft palate (palatoschisis which can also occur together as cleft lip and palate are variations of a type of clefting Congenital