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Lips are 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#REDIRECT Erogenous zone An erogenous zone (from Greek , ''érōs'' "love"; and English ''-genous'' "producing", from Greek , ''-genḗs'' "born") is an area of the human body The human body is the structure of a human being. It is composed of ...
when used in
kiss A kiss is the touch or pressing of one's lips against another person or an object. Cultural connotations of kissing vary widely. Depending on the culture and context, a kiss can express sentiments of love Love encompasses a range of str ...

kiss
ing and other acts of
intimacy An intimate relationship is an interpersonal relationship The concept of interpersonal relationship involves social associations, connections, or affiliations between two or more people. Interpersonal relationships vary in their degree of ...
.


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 The vermilion border (sometimes spelled vermillion border), also called margin or zone, is the normally sharp demarcation between the lip Lips are a visible body part at the mouth of many animals, including humans. Lips are soft, movable, an ...
, 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 Image:MouthCupidBow.jpg, Cupid's bow feature on a human lip The Cupid's bow is a facial feature where the double curve of a human upper lip is said to resemble the bow (weapon), bow of Cupid, the Roman god of erotic love. The peaks of the bow coinci ...

cupid's bow
. The fleshy protuberance located in the center of the upper lip is a
tubercle Image:Mammillaria marksiana.jpg, 250px, This view of the cactus ''Mammillaria marksiana'' shows its pattern of prominent tubercles, with the spines emanating from each tubercle's tip. In anatomy, a tubercle (literally 'small tuber', Latin for 'lum ...
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 The nasal septum () separates the left and right airways of the nasal cavity, dividing the two nostrils. It is depressed by the depressor septi nasi muscle. Structure The fleshy external end of the nasal septum is called the columella ...
is called the
philtrum The philtrum ( la, philtrum from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the f ...

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 Melanocytes are melanin-producing neural crest-derived cells located in the bottom layer (the stratum basale The ''stratum basale'' (basal layer, sometimes referred to as ''stratum germinativum'') is the deepest layer of the five layers of the ...
(cells which produce melanin
pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compound , CH4; is among the simplest organic compou ...
, which give skin its color). Because of this, the
blood vessel The blood vessels are the components of the circulatory system The circulatory system, also called the cardiovascular system or the vascular system, is an organ system An organ system is a biological system A biological system is a comp ...
s 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 A mucous membrane or mucosa is a biological membrane, membrane that lines various cavities in the body and covers the surface of internal organs. It consists of one or more layers of Epithelium, epithelial cells overlying a layer of loose connect ...
of the inside of the mouth. The lip skin is not hairy and does not have
sweat gland Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate Vertebrates () comprise all species of an ...
s. 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 Cheilitis is a medical condition characterized by inflammation Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or ...
more easily. The lower lip is formed from the
mandibular prominence The mandibular prominence is an embryological structure which gives rise to the lower portion of the face. The human mandible, mandible and lower lip derive from it.first pharyngeal arch The pharyngeal arches, also known as visceral arches'','' are structures seen in the Animal embryonic development, embryonic development of vertebrates that are recognisable precursors for many structures. In fish, the arches are known as the b ...
. The lower lip covers the anterior
body of the mandible In anatomy Anatomy (Greek ''anatomē'', 'dissection') is the branch of biology concerned with the study of the structure of organism In biology, an organism (from Ancient Greek, Greek: ὀργανισμός, ''organismos'') is any ind ...
. It is lowered by the
depressor labii inferioris muscle The depressor labii inferioris (or quadratus labii inferioris) is a facial muscle that helps lower the bottom lip. Structure This muscle arises from the oblique line of the mandible, and inserts on the skin of the lower lip, blending in with the ...
and the
orbicularis oris In human anatomy The human body is the structure of a human being Humans (''Homo sapiens'') are the most populous and widespread species In biology, a species is the basic unit of biological classification, classification and a tax ...

orbicularis oris
borders it inferiorly. The upper lip covers the
anterior surface of the body of the maxilla The maxilla (plural: ''maxillae'' ) in vertebrates Vertebrates () comprise all species of animals within the subphylum Vertebrata () (chordates with vertebral column, backbones). Vertebrates represent the overwhelming majority of the phylum C ...
. Its upper half is of usual skin color and has a depression at its center, directly under the nasal septum, called the
philtrum The philtrum ( la, philtrum from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the f ...

philtrum
, which is Latin for "lower nose", while its lower half is a markedly different, red-colored skin tone more similar to the color of the inside of the mouth, and the term ''vermillion'' refers to the colored portion of either the upper or lower lip. It is raised by the
levator labii superioris The levator labii superioris (pl. ''levatores labii superioris'', also called quadratus labii superioris, pl. ''quadrati labii superioris'') is a muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of t ...

levator labii superioris
and is connected to the
lower lip Lips are 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 e ...
by the thin lining of the lip itself. Thinning of the vermilion of the upper lip and flattening of the
philtrum The philtrum ( la, philtrum from Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the f ...

philtrum
are two of the facial characteristics of
fetal alcohol syndrome Fetal alcohol spectrum disorders (FASDs) are a group of conditions that can occur in a person whose mother drank alcohol In chemistry, alcohol is an organic compound that carries at least one hydroxyl functional group (−OH) bound to ...

fetal alcohol syndrome
, a lifelong
disability A disability is any condition that makes it more difficult for a person to do certain activities or effectively interact with the world around them (socially or materially). These conditions, or impairments, may be Cognitive disability, cogn ...

disability
caused by the mother's consumption of alcohol during pregnancy.


Microanatomy

The skin of the lips is
stratified squamous epithelium A stratified squamous epithelium consists of squamous (flattened) epithelial cell Epithelium is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biolo ...

stratified squamous epithelium
. The mucous membrane is represented by a large area in the
sensory cortexThe sensory cortex can refer informally to the primary somatosensory cortex The primary somatosensory cortex is located in the postcentral gyrus, and is part of the somatosensory system The somatosensory system is a part of the sensory nervous s ...
, and is therefore highly sensitive. The ''Frenulum Labii Inferioris'' is the
frenulum A frenulum (or frenum, plural: frenula or frena, from the Latin ''frēnulum'', "little bridle", the diminutive A diminutive is a root word A root (or root word) is the core of a word that is irreducible into more meaningful elements. In morph ...

frenulum
of the lower lip. The ''Frenulum Labii Superioris'' is the frenulum of the upper lip.


Nerve supply

*
Trigeminal nerve The trigeminal nerve (the fifth cranial nerve, or simply CN V) is a nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves Cranial nerves are the nerve A ner ...

Trigeminal nerve
** The
infraorbital nerve The infraorbital nerve is a branch of the maxillary nerve, itself a branch of the trigeminal nerve The trigeminal nerve (the fifth cranial nerve, or simply CN V) is a nerve responsible for sensation in the face and motor functions such as bitin ...
is a branch of the
maxillary
maxillary
branch. It supplies not only the upper lip but also much of the skin of the face between the upper lip and the lower eyelid, except for the bridge of the nose. ** The
mental nerve The mental nerve is a sensory nerve A sensory nerve, or afferent nerve, is a general anatomic term for a nerve A nerve is an enclosed, cable-like bundle of nerve fibers called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve f ...
is a branch of the
mandibular In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movable ...
branch ( via the
inferior alveolar nerve The inferior alveolar nerve (sometimes called the inferior dental nerve) is a branch of the mandibular nerve, which is itself the third branch of the trigeminal nerve The trigeminal nerve (the fifth cranial nerve, or simply CN V) is a nerve res ...
). It supplies the skin and mucous membrane of the lower lip and labial
gingiva The gums or gingiva (plural: ''gingivae'') consist of the mucosal A mucous membrane or mucosa is a membrane Image:Schematic size.jpg, up150px, Schematic of size-based membrane exclusion A membrane is a selective barrier; it allows some things ...

gingiva
(gum) anteriorly.


Blood supply

The
facial artery The facial artery (external maxillary artery in older texts) is a branch of the external carotid artery The external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it splits into the external ...
is one of the six non-terminal branches of the
external carotid artery The external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it splits into the external and internal carotid artery. External carotid artery supplies blood to the face and neck. Structure Th ...

external carotid artery
. This artery supplies both lips by its superior and inferior labial branches. Each of the two branches ''bifurcate'' and ''anastomose'' with their companion branch from the other terminal.


Muscles

The muscles acting on the lips are considered part of the muscles of
facial expression A facial expression is one or more motions or positions of the muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that ...
. All muscles of facial expression are derived from the
mesoderm The mesoderm is the middle layer of the three germ layer A germ layer is a primary layer of cell (biology), cells that forms during embryonic development. The three germ layers in vertebrates are particularly pronounced; however, all eumetazoa ...

mesoderm
of the second
pharyngeal arch The pharyngeal arches, also known as visceral arches'','' are structures seen in the embryonic development An embryo is the early stage of development of a multicellular organism A multicellular organism is an organism that consists of mor ...
, and are therefore supplied (motor supply) by the nerve of the second pharyngeal arch, the
facial nerve The facial nerve (the labyrinthine segment) is the seventh Cranial nerves, cranial nerve, or simply CN VII. It emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste sensation ...

facial nerve
(7th
cranial nerve Cranial nerves are the nerve A nerve is an enclosed, cable-like bundle of nerve fibers called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, ...
). The muscles of facial expression are all specialized members of the
panniculus carnosus The panniculus carnosus is a part of the subcutaneous tissue The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, superficial fascia, is the lowermost layer of the integumentary system The integumentary system is the s ...
, which attach to the
dermis The dermis or corium is a layer of skin between the epidermis (skin), epidermis (with which it makes up the cutis (anatomy), cutis) and subcutaneous tissues, that primarily consists of dense irregular connective tissue and cushions the body from s ...
and so wrinkle, or dimple the overlying skin. Functionally, the muscles of facial expression are arranged in groups around the
orbits In celestial mechanics Celestial mechanics is the branch of astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical obj ...
, nose and mouth. The muscles acting on the lips: *
Buccinator The buccinator () is a thin quadrilateral muscle occupying the interval between the maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone A bone is a Stiffness, rigid tissue (anato ...
*
Orbicularis oris In human anatomy The human body is the structure of a human being Humans (''Homo sapiens'') are the most populous and widespread species In biology, a species is the basic unit of biological classification, classification and a tax ...
(a complex of muscles, formerly thought to be a single
sphincter A sphincter is a circular muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A give ...
or ring of muscle) * Anchor point for several muscles ** Modiolus * Lip elevation **
Levator labii superioris The levator labii superioris (pl. ''levatores labii superioris'', also called quadratus labii superioris, pl. ''quadrati labii superioris'') is a muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of t ...

Levator labii superioris
** levator labii superioris alaeque nasi **
Levator anguli oris The levator anguli oris (caninus) is a Facial muscles, facial muscle of the mouth arising from the canine fossa, immediately below the infraorbital foramen. It Elevation (kinesiology), elevates angle of mouth medially. Its fibers are inserted into ...

Levator anguli oris
** Zygomaticus minor **
Zygomaticus major The zygomaticus major is a muscle Muscle is a soft tissue found in most animals. Muscle cells contain protein Proteins are large biomolecules or macromolecules that are comprised of one or more long chains of amino acid residue (biochemi ...
* Lip depression **
Risorius The risorius is a muscle of facial expression which 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 mouth. It is a narrow bundle of fibers, broades ...

Risorius
**
Depressor anguli oris The depressor anguli oris muscle (triangularis muscle) is a facial muscle The facial muscles are a group of striated skeletal muscles supplied by the facial nerve (cranial nerve VII) that, among other things, control facial expression. These mu ...
**
Depressor labii inferioris The depressor labii inferioris (or quadratus labii inferioris) is a facial muscle The facial muscles are a group of striated skeletal muscles supplied by the facial nerve (cranial nerve VII) that, among other things, control facial expression. T ...
**
Mentalis The mentalis muscle is a paired central Skeletal muscle, muscle of the lower lip, situated at the tip of the chin. It originates from the mentum of the mandible, and inserts into the soft tissue of the chin. It is sometimes referred to as the "pout ...

Mentalis


Functions


Food intake

Because they have their own muscles and bordering muscles, the lips are easily movable. 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, to hold food and drink inside, and to keep out unwanted objects. Through making a narrow
funnel A funnel is a tube or pipe that is wide at the top and narrow at the bottom, used for guiding liquid or powder into a small opening. Funnels are usually made of stainless steel Stainless steel is a group of that contain a minimum of appr ...

funnel
with the lips, the suction of the mouth is increased. This suction is essential for babies to breast feed. Lips can also be used to suck in other contexts, such as sucking on a straw to drink liquids.


Articulation

The lips serve for creating different sounds—mainly labial,
bilabial In phonetics, a bilabial consonant is a labial consonant place of articulation, articulated with both lips. Transcription The bilabial consonants identified by the International Phonetic Alphabet (IPA) are: Owere Igbo language, Igbo has a six-wa ...

bilabial
, and
labiodental
labiodental
consonant sounds as well as vowel rounding—and thus are an important part of the speech apparatus. The lips enable
whistling Whistling without the use of an artificial whistle A whistle is an instrument which produces sound from a stream of gas, most commonly air. It may be mouth-operated, or powered by air pressure, steam, or other means. Whistles vary in size fr ...
and the performing of wind instruments such as the trumpet,
clarinet The clarinet is a family of woodwind instrument Woodwind instruments are a family of musical instruments A musical instrument is a device created or adapted to make musical sounds. In principle, any object that produces sound can be cons ...

clarinet
, flute, and saxophone. People who have
hearing loss Hearing loss is a partial or total inability to hear Hearing, or auditory perception, is the ability to perceive Sound, sounds by detecting Vibration, vibrations, changes in the pressure of the surrounding medium through time, through a ...
may unconsciously or consciously lip read to understand speech without needing to perceive the actual sounds.


Tactile organ

The lip has many
nerve ending A free nerve ending (FNE) or bare nerve ending, is an unspecialized, afferent nerve fiber Afferent nerve fibers refer to axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences ...
s and reacts as part of the tactile (touch) senses. Lips are very sensitive to touch, warmth, and cold. It is therefore an important aid for exploring unknown objects for babies and toddlers.


Erogenous zone

Because of their high number of nerve endings, the lips are an
erogenous zone#REDIRECT Erogenous zone An erogenous zone (from Greek , ''érōs'' "love"; and English ''-genous'' "producing", from Greek , ''-genḗs'' "born") is an area of the human body The human body is the structure of a human being. It is composed of ...
. The lips therefore play a crucial role in
kissing A kiss is the touch or pressing of one's lips against another person or an object. Cultural connotations of kissing vary widely. Depending on the culture and context, a kiss can express sentiments of love, Passion (emotion), passion, romance (l ...
and other acts of intimacy. 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 Testosterone is the primary sex hormone and anabolic steroid in males. In humans, testosterone plays a key role in the development of Male reproductive system, male reproductive tissues such as testes and prostate, as well as promoting secondar ...
on a man's facial structure, the effects of a woman's
oestrogen Estrogens or oestrogens, are a class of natural or synthetic sex hormone Sex hormones, also known as sex steroids, gonadocorticoids and gonadal steroids, are steroid hormone A steroid hormone is a steroid that acts as a hormone. Steroid hor ...

oestrogen
levels serve to maintain a relatively "childlike" and youthful facial structure during puberty and during final maturation. It has been shown that the more oestrogen a woman has, the larger her eyes and the fuller her lips, characteristics which are perceived as more feminine. 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. A woman's lipstick (or
collagen Collagen () is the main structural protein Proteins are large biomolecule , showing alpha helices, represented by ribbons. This poten was the first to have its suckture solved by X-ray crystallography by Max Perutz and Sir John Cowder ...

collagen
lip enhancement) attempts to take advantage of this fact by creating the illusion that a woman has more oestrogen than she actually has, and thus that she is more fertile and attractive. Lip size is linked to sexual attraction in both men and women. Women are attracted to men with masculine lips, that are more middle size and not too big or too small; they are to be rugged and sensual. In general, the researchers found that a small nose, big eyes and voluptuous lips are sexually attractive both in men and women. The lips may temporarily swell during sexual arousal due to engorgement with blood.


Facial expression

The lips contribute substantially to
facial expression A facial expression is one or more motions or positions of the muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that ...
s. The lips visibly express emotions such as a
smile A smile is formed primarily by flexing the muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and animal life rely on many organs that co-exist in org ...

smile
or frown, iconically by the curve of the lips forming an up-open or down-open
parabola In mathematics Mathematics (from Greek: ) includes the study of such topics as numbers ( and ), formulas and related structures (), shapes and spaces in which they are contained (), and quantities and their changes ( and ). There is no ...

parabola
, respectively. Lips can also be made pouty when whining, or perky to be provocative.


Clinical significance

As an organ of the body, the lip can be a focus of disease or show symptoms of a disease: * One of the most frequent changes of the lips is a blue coloring due to
cyanosis Cyanosis is the change of body Tissue (biology), tissue color to a bluish-purple hue as a result of having decreased amounts of oxygen bound to the hemoglobin in the Red blood cell, red blood cells of the capillary bed. Body tissues that reflect ...
; the blood contains less oxygen, and thus has a dark red to blue color, which shows through the thin skin. Cyanosis is the reason why corpses sometimes have blue lips. In cold weather cyanosis can appear, so especially in the winter, blue lips may not be an uncommon sight. * Inflammation of the lips is termed
cheilitis Cheilitis is a medical condition characterized by inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogen In biology Biology is the natural sci ...
. This can be in several forms such as
chapped lips
chapped lips
(dry, peeling lips),
angular cheilitis Angular cheilitis (AC) is inflammation Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogen In biology Biology is the natural science that studies life a ...

angular cheilitis
(inflammation of the corners of the mouth),
herpes labialis Herpes labialis, commonly known as cold sores, is a type of infection An infection is the invasion of an organism's body tissues by disease-causing agents, their multiplication, and the reaction of host A host is a person responsible ...

herpes labialis
(cold sore, a form of
herpes simplex Herpes simplex is a viral infection A viral disease (or viral infection) occurs when an organism's body is invaded by pathogen In biology Biology is the natural science that studies life and living organisms, including their anatomy ...
) and actinic cheilitis (chronically sun damaged lips). *
Cleft lip A cleft lip contains an opening in the upper lip Lips are 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. Hu ...
is a type of
birth defect A birth defect, also known as a congenital disorder, is a condition present at birth Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiat ...
that can be successfully treated with surgery. *
Carcinoma Carcinoma is a malignancy that develops from epithelial cells Epithelium () is one of the four basic types of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological k ...
(a malignant cancer that arises from epithelial cells) at the lips, is caused predominantly by using tobacco and overexposure of sunlight. Alcohol appears to increase the carcinoma risk associated with tobacco use. It is most often a diffuse and often hyperkeratinised lesion, occasionally has the form of nodules and grows infiltratively, and can also be a combination of the two types. It more often occurs at the lower lip, where it is also much more malign. The lower lip carcinoma is exclusively planocellular carcinoma, whereas at the upper lip, it can also be basocellular carcinoma.


Society and culture

Lips are often viewed as a symbol of sensuality and sexuality. This has many origins; above all, the lips are a very sensitive erogenous and tactile organ. 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 In Freudian Sigmund Freud ( , ; born Sigismund Schlomo Freud; 6 May 1856 – 23 September 1939) was an Austrian neurologist Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is a branch of ...
of the psychology according to
Sigmund Freud Sigmund Freud ( , ; born Sigismund Schlomo Freud; 6 May 1856 – 23 September 1939) was an Austrian neurologist Neurology (from el, νεῦρον (neûron), "string, nerve" and the suffix -logia, "study of") is a branch of medicine M ...

Sigmund Freud
).
Lip piercing A lip piercing is a type of body piercing Body piercing, which is a form of body modification, is the practice of puncturing or cutting a part of the human body, creating an opening in which jewelry may be worn, or where an Implant (medicin ...

Lip piercing
or
lip augmentationLip augmentation is a type of procedure that aims to increase lip fullness through enlargement using fillers such as hyaluronic acid, fat or implants. History Full lips with an accentuated border have often been associated with beauty and youth. T ...
is sometimes carried out for cosmetic reasons. Products designed for use on the lips include lipstick,
lip gloss Lip gloss is a cosmetic used primarily to give lips a glossy lustre, and sometimes to add a subtle color. It is distributed as a liquid or a soft solid (not to be confused with lip balm, which generally has medical or soothing purposes or lipsti ...
and
lip balm Homemade lip balms Lip balm or lip salve is a wax , a typical wax ester. Image:Beeswax foundation.jpg, Commercial honeycomb foundation, made by pressing beeswax between patterned metal rollers. Waxes are a diverse class of organic compounds that ...

lip balm
.


Other animals

In most vertebrates, the lips are relatively unimportant folds of tissue lying just outside the jaws. However, in
mammal Mammals (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be i ...
s, they become much more prominent, being separated from the jaws by a deep cleft (a notable exception being the
naked mole-rat The naked mole-rat (''Heterocephalus glaber''), also known as the sand puppy, is a burrowing rodent native to parts of East Africa East Africa, Eastern Africa, or East of Africa is the eastern sub-region A subregion is a part of a larger ...
, whose lips close behind the front teeth). They are also more mobile in mammals than in other groups, since it is only in this group that they have any attached muscles. In some
teleost Teleostei (Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximat ...
fish, the lips may be modified to carry sensitive
barbels carp have two pairs of barbels, the second pair being quite small. Image:Arowana.jpg, 250px, This turtle_anatomy,_a_barbel_is_a_slender,_whiskerlike_sensory_organ_(anatomy).html" ;"title="fish anatomy">Asian arowana has large, protruding barbels ...
. In birds and turtles, the lips are hard and
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin Alpha-keratin, or α-keratin, is a type of keratin Keratin () is one of a family of fibrous structural proteins known as Scleroprot ...

keratin
ous, forming a solid
beak The beak, bill, and/or rostrum is an external anatomical structure found mostly in birds Birds are a group of warm-blooded vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellu ...

beak
. Clevosaurids like ''Clevosaurus'' are notable for the presence of bone "lips"; in these species the tooth-like jaw projections common to all sphenodontians form a beak-like edge around the jaws, protecting the teeth within.Jones MEH (2009). "Dentary tooth shape in Sphenodon and its fossil relatives (Diapsida: Lepidosauria: Rhynchocephalia)". In Koppe T, Meyer G, Alt KW, (eds). ''Interdisciplinary Dental Morphology, Frontiers of Oral Biology'' (vol 13). Griefswald, Germany; Karger. 9–15.


See also

* Stiff upper lip


References


Further reading

* * *


External links

* *
Anatomy at oralhealth.dent.umich.edu
* * {{Authority control Facial features Mouth Human anatomy, Lips Human head and neck Speech organs Human mouth anatomy Digestive system Lips, *