human anatomy Human anatomy (gr. ἀνατομία, "dissection", from ἀνά, "up", and τέμνειν, "cut") is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross ...

, the mouth is the first portion of the

alimentary canal The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. ...

that receives

food Food is any substance consumed by an organism for Nutrient, nutritional support. Food is usually of plant, animal, or Fungus, fungal origin and contains essential nutrients such as carbohydrates, fats, protein (nutrient), proteins, vitamins, ...

and produces

saliva Saliva (commonly referred as spit or drool) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which ...

. The

oral mucosa The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed '' lamina propria''. The oral cavity has sometimes been des ...

is the mucous membrane

epithelium Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...

lining the inside of the mouth. In addition to its primary role as the beginning of the

digestive system The human digestive system consists of the gastrointestinal tract plus the accessory organs of digestion (the tongue, salivary glands, pancreas, liver, and gallbladder). Digestion involves the breakdown of food into smaller and smaller compone ...

, the mouth also plays a significant role in

communication Communication is commonly defined as the transmission of information. Its precise definition is disputed and there are disagreements about whether Intention, unintentional or failed transmissions are included and whether communication not onl ...

. While primary aspects of the

voice The human voice consists of sound made by a human being using the vocal tract, including talking, singing, laughing, crying, screaming, shouting, humming or yelling. The human voice frequency is specifically a part of human sound produ ...

are produced in the

throat In vertebrate anatomy, the throat is the front part of the neck, internally positioned in front of the vertebrae. It contains the Human pharynx, pharynx and larynx. An important section of it is the epiglottis, separating the esophagus from the t ...

, the

tongue The tongue is a Muscle, muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for chewing and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper s ...

lip The lips are a horizontal pair of soft appendages attached to the jaws and are the most visible part of the mouth of many animals, including humans. Mammal lips are soft, movable and serve to facilitate the ingestion of food (e.g. sucklin ...

s, and

jaw The jaws are a pair of opposable articulated structures at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth ...

are also needed to produce the range of sounds included in

speech Speech is the use of the human voice as a medium for language. Spoken language combines vowel and consonant sounds to form units of meaning like words, which belong to a language's lexicon. There are many different intentional speech acts, suc ...

. The mouth consists of two regions, the vestibule and the oral cavity proper. The mouth, normally moist, is lined with a

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...

, and contains the

teeth A tooth (: teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...

. The lips mark the transition from mucous membrane to

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

, which covers most of the

body Body may refer to: In science * Physical body, an object in physics that represents a large amount, has mass or takes up space * Body (biology), the physical material of an organism * Body plan, the physical features shared by a group of anim ...

Structure

Oral cavity

The mouth consists of two regions: the vestibule and the oral cavity proper. The vestibule is the area between the teeth, lips and cheeks. The oral cavity is bounded at the sides and in front by the

alveolar process The alveolar process () is the portion of bone containing the tooth sockets on the jaw bones (in humans, the maxilla and the mandible). The alveolar process is covered by gums within the mouth, terminating roughly along the line of the mandibu ...

(containing the

) and at the back by the isthmus of the fauces. Its roof is formed by the

hard palate The hard palate is a thin horizontal bony plate made up of two bones of the facial skeleton, located in the roof of the mouth. The bones are the palatine process of the maxilla and the horizontal plate of palatine bone. The hard palate spans ...

. The floor is formed by the

mylohyoid muscle The mylohyoid muscle or diaphragma oris is a paired muscle of the neck. It runs from the Human mandible, mandible to the hyoid bone, forming the floor of the oral cavity of the human mouth, mouth. It is named after its two attachments near the mo ...

s and is occupied mainly by the anterior two-thirds of the

. A

– the

, lines the sides and under surface of the tongue to the gums, and lines the inner aspect of the jaw (

mandible In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

). It receives secretions from the submandibular and

sublingual Sublingual (List of abbreviations used in medical prescriptions, abbreviated SL), from the Latin for "under the tongue", refers to the pharmacological route of administration by which substances diffuse into the blood through Tissue (biology), t ...

salivary gland The salivary glands in many vertebrates including mammals are exocrine glands that produce saliva through a system of ducts. Humans have three paired major salivary glands ( parotid, submandibular, and sublingual), as well as hundreds of min ...

s. The posterior border of the oral cavity (ie, junction between the oral cavity and the

oropharynx The pharynx (: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the esophagus and trachea (the tubes going down to the stomach and the lungs respectively). It is found in vertebrates and invertebrates, though its ...

) includes the junction of the

and the

soft palate The soft palate (also known as the velum, palatal velum, or muscular palate) is, in mammals, the soft biological tissue, tissue constituting the back of the roof of the mouth. The soft palate is part of the palate of the mouth; the other part is ...

superiorly, the circumvallate papillae of the

inferiorly, and the retromolar trigone.

Lips

The

s come together to close the opening of the mouth, forming a line between the upper and lower lip. In

facial expression Facial expression is the motion and positioning of the muscles beneath the skin of the face. These movements convey the emotional state of an individual to observers and are a form of nonverbal communication. They are a primary means of conveying ...

, this ''mouth line'' is iconically shaped like an up-open

parabola In mathematics, a parabola is a plane curve which is Reflection symmetry, mirror-symmetrical and is approximately U-shaped. It fits several superficially different Mathematics, mathematical descriptions, which can all be proved to define exactl ...

in a

smile A smile is a facial expression formed primarily by flexing the muscles at the sides of the mouth. Some smiles include a contraction of the muscles at the corner of the eyes, an action known as a Duchenne smile. Among humans, a smile expresses d ...

, and like a down-open parabola in a

frown A frown (also known as a scowl) is a facial expression in which the eyebrows are brought together, and the forehead is wrinkled, usually indicating displeasure, sadness or worry, or less often confusion or concentration. The appearance of a fr ...

. A ''down-turned mouth'' means a mouth line forming a down-turned parabola, and when permanent can be normal. Also, a ''down-turned mouth'' can be part of the presentation of

Prader–Willi syndrome Prader–Willi syndrome (PWS) is a rare genetic disorder caused by a loss of function of specific genes on chromosome 15. In newborns, symptoms include hypotonia, weak muscles, poor feeding, and slow development. Beginning in childhood, those ...

Nerve supply

The teeth and the

periodontium The periodontium () is the specialized tissues that both surround and support the teeth, maintaining them in the maxillary and mandibular bones. Periodontics is the dental specialty that relates specifically to the care and maintenance of the ...

(the tissues that support the teeth) are innervated by the maxillary and

mandibular nerve In neuroanatomy, the mandibular nerve (V) is the largest of the three divisions of the trigeminal nerve, the fifth Cranial nerves, cranial nerve (CN V). Unlike the other divisions of the trigeminal nerve (ophthalmic nerve, maxillary nerve) which ...

s – divisions of the

trigeminal nerve In neuroanatomy, the trigeminal nerve (literal translation, lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for Sense, sensation in the face and motor functions ...

. Maxillary (upper) teeth and their associated

periodontal ligament The periodontal ligament, commonly abbreviated as the PDL, are a group of specialized connective tissue fibers that essentially attach a tooth to the alveolar bone within which they sit. It inserts into root cementum on one side and onto alveo ...

are innervated by the superior alveolar nerves, branches of the maxillary division, termed the posterior superior alveolar nerve, anterior superior alveolar nerve, and the variably present middle superior alveolar nerve. These nerves form the superior dental plexus above the maxillary teeth. The mandibular (lower) teeth and their associated periodontal ligament are innervated by the

inferior alveolar nerve The inferior alveolar nerve (IAN) (also the inferior dental nerve) is a sensory branch of the mandibular nerve (CN V3) (which is itself the third branch of the trigeminal nerve (CN V)). The nerve provides sensory innervation to the lower/mandibu ...

, a branch of the mandibular division. This nerve runs inside the mandible, within the inferior alveolar canal below the mandibular teeth, giving off branches to all the lower teeth ( inferior dental plexus). The

of the gingiva (gums) on the

facial A facial is a family of skin care treatments for the face, including steam, exfoliation (physical and chemical), extraction, creams, lotions, facial masks, peels, and massage. They are normally performed in beauty salons, but are also a c ...

(labial) aspect of the maxillary

incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...

s, canines and

premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...

teeth is innervated by the superior labial branches of the

infraorbital nerve The infraorbital nerve is a branch of the maxillary nerve (itself a branch of the trigeminal nerve (CN V)). It arises in the pterygopalatine fossa. It passes through the inferior orbital fissure to enter the orbit. It travels through the orbit, ...

. The posterior superior alveolar nerve supplies the gingiva on the facial aspect of the maxillary molar teeth. The gingiva on the

palatal The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sepa ...

aspect of the maxillary teeth is innervated by the

greater palatine nerve The greater palatine nerve is a branch of the pterygopalatine ganglion. This nerve is also referred to as the anterior palatine nerve, due to its location anterior to the lesser palatine nerve. It carries both general sensory fibres from the ma ...

apart from in the incisor region, where it is the nasopalatine nerve (long sphenopalatine nerve). The gingiva of the lingual aspect of the mandibular teeth is innervated by the sublingual nerve, a branch of the

lingual nerve The lingual nerve carries sensory innervation from the anterior two-thirds of the tongue. It contains fibres from both the mandibular division of the trigeminal nerve (CN V) and from the facial nerve (CN VII). The fibres from the trigeminal nerve ...

. The gingiva on the facial aspect of the mandibular incisors and canines is innervated by the mental nerve, the continuation of the inferior alveolar nerve emerging from the

mental foramen The mental foramen is one of two foramina (openings) located on the anterior surface of the mandible. It is part of the mandibular canal. It transmits the terminal branches of the inferior alveolar nerve and the mental vessels. Structure Th ...

. The gingiva of the buccal (cheek) aspect of the mandibular molar teeth is innervated by the

buccal nerve The buccal nerve (long buccal nerve) is a sensory nerve of the face arising from the mandibular nerve (CN V3) (which is itself a branch of the trigeminal nerve). It conveys sensory information from the skin of the cheek, and parts of the oral mu ...

(long buccal nerve).

Development

The

philtrum The philtrum (, from Ancient Greek , lit. 'love charm') or medial cleft is a vertical indentation in the middle area of the upper lip, common to therian mammals, extending in humans from the nasal septum to the tubercle of the upper lip. Toget ...

is the vertical depression formed between the ''philtral ridges'' between the upper lip and the nasal septum, formed where the nasomedial and

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

ry processes meet during embryo development. When these processes fail to fuse fully, a

cleft lip A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nasal cavi ...

cleft palate A cleft lip contains an opening in the upper lip that may extend into the nose. The opening may be on one side, both sides, or in the middle. A cleft palate occurs when the palate (the roof of the mouth) contains an opening into the nose. The ...

, or both can result. The nasolabial folds are the deep creases of tissue that extend from the nose to the sides of the mouth. One of the first signs of age on the human face is the increase in prominence of the nasolabial folds.

Function

The mouth plays an important role in

eating Eating (also known as consuming) is the ingestion of food. In biology, this is typically done to provide a heterotrophic organism with energy and nutrients and to allow for growth. Animals and other heterotrophs must eat in order to survive – ...

drink A drink or beverage is a liquid intended for human consumption. In addition to their basic function of satisfying thirst, drinks play important roles in human culture. Common types of drinks include plain drinking water, milk, juice, smoothie ...

ing, and speaking.

Mouth breathing Mouth breathing, medically known as chronic oral ventilation, is long-term breathing through the mouth. It often is caused by an obstruction to breathing through the nose, the innate breathing organ in the human body. However, by the early 20 ...

refers to the act of breathing through the mouth (as a temporary backup system) if there is an obstruction to breathing through the nose, which is the designated breathing organ for the human body.

Infant In common terminology, a baby is the very young offspring of adult human beings, while infant (from the Latin word ''infans'', meaning 'baby' or 'child') is a formal or specialised synonym. The terms may also be used to refer to juveniles of ...

s are born with a

sucking reflex Primitive reflexes are reflex actions originating in the central nervous system that are exhibited by normal infants, but not neurologically intact adults, in response to particular Stimulus (physiology), stimuli. These reflexes are suppressed by t ...

, by which they

instinct Instinct is the inherent inclination of a living organism towards a particular complex behaviour, containing innate (inborn) elements. The simplest example of an instinctive behaviour is a fixed action pattern (FAP), in which a very short to me ...

ively know to suck for nourishment using their lips and

. The mouth also helps in

chewing Chewing or mastication is the process by which food is crushed and ground by the teeth. It is the first step in the process of digestion, allowing a greater surface area for digestive enzymes to break down the foods. During the mastication proc ...

and

biting Biting is an action involving a set of teeth closing down on an object. It is a common zoological behavior, being found in toothed animals such as mammals, reptiles, amphibians, fishes, and arthropods. Biting is also an action humans participate ...

food. For some disabled people, especially many disabled artists, who through illness, accident or congenital disability have lost dexterity, their mouths take the place of their hands, when typing, texting, writing, making

drawing Drawing is a Visual arts, visual art that uses an instrument to mark paper or another two-dimensional surface, or a digital representation of such. Traditionally, the instruments used to make a drawing include pencils, crayons, and ink pens, some ...

painting Painting is a Visual arts, visual art, which is characterized by the practice of applying paint, pigment, color or other medium to a solid surface (called "matrix" or "Support (art), support"). The medium is commonly applied to the base with ...

s and other works of art by maneuvering brushes and other tools, in addition to the basic oral functions. Mouth painters hold the brush in their mouth or between their teeth and maneuver it with their tongue and cheek muscles, but mouth painting can be strenuous for neck and jaw muscles since the head has to perform the same back and forth movement as a hand does when painting. A

male Male (Planet symbols, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or Egg cell, ovum, in the process of fertilisation. A male organism cannot sexual repro ...

mouth can hold, on average, , while a

female An organism's sex is female ( symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction. A female has larger gametes than a male. Females and ...

mouth holds .

References

External links

* * {{Authority control Facial features Human anatomy Human head and neck Speech organs Human mouth anatomy digestive system