Human mouth

In human anatomy, the mouth is the first portion of the alimentary canal that receives food and produces saliva.[1] The oral mucosa is the mucous membrane epithelium lining the inside of the mouth.

In addition to its primary role as the beginning of the digestive system, in humans the mouth also plays a significant role in communication. While primary aspects of the voice are produced in the throat, the tongue, lips, and jaw are also needed to produce the range of sounds included in human language.

The mouth consists of two regions, the vestibule and the oral cavity proper. The mouth, normally moist, is lined with a mucous membrane, and contains the teeth. The lips mark the transition from mucous membrane to skin, which covers most of the body.

Mouth
Illu01 head neck
Head and neck
Mouth
A closed human mouth
Details
Identifiers
Latinos, cavitas oralis
MeSHD009055
TAA01.1.00.010
FMA49184
Anatomical terminology

Structure

Oral cavity

Amigdalas
Photograph of the inside of an open human mouth. One palatine tonsil is also visible (white).
Blausen 0653 MouthAnatomy
Anatomy of the mouth.
Floor of the mouth
Floor of the mouth with Lingual frenum and sublingual fold

The mouth, consists of 2 regions, the vestibule and the oral cavity proper. The vestibule is the area between the teeth, lips and cheeks.[2] The oral cavity is bounded at the sides and in front by the alveolar process (containing the teeth) and at the back by the isthmus of the fauces. Its roof is formed by hard palate at the front, and a soft palate at the back. The uvula projects downwards from the middle of the soft palate at its back. The floor is formed by the mylohyoid muscles and is occupied mainly by the tongue. A mucous membrane – the oral mucosa, lines the sides and under surface of the tongue to the gums, lining the inner aspect of the jaw (mandible). It receives the secretions from the submandibular and sublingual salivary glands. [1]

Orifice

While shut, the orifice of the mouth forms a line between the upper and lower lip. In facial expression, this mouth line is iconically shaped like an up-open parabola in a smile, and like a down-open parabola in a frown. 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.[3]

Nerve supply

The teeth and the periodontium (i.e. the tissues that support the teeth) are innervated by the maxillary and mandibular divisions of the trigeminal nerve. Maxillary (upper) teeth and their associated periodontal ligament 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, 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).[4][5] The oral mucosa of the gingiva (gums) on the facial (labial) aspect of the maxillary incisors, canines and premolar teeth is innervated by the superior labial branches of the infraorbital nerve. The posterior superior alveolar nerve supplies the gingiva on the facial aspect of the maxillary molar teeth. The gingiva on the palatal aspect of the maxillary teeth is innervated by the greater palatine nerve 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 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 gingiva of the buccal (cheek) aspect of the mandibular molar teeth is innervated by the buccal nerve (long buccal nerve).[6]

Development

The philtrum is the vertical groves in the upper lip, formed where the nasomedial and maxillary processes meet during embryo development. When these processes fail to fuse fully, either a hare lip or cleft palate, (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, drinking, breathing and speaking. Infants are born with a sucking reflex, by which they instinctively know to suck for nourishment using their lips and jaw. The mouth also helps in chewing and biting food.

A male mouth can hold, on average, 71.2 ml, while a female mouth holds 55.4 ml.[7]

See also

References

  1. ^ Maton, Anthea; Jean Hopkins; Charles William McLaughlin; Susan Johnson; Maryanna Quon Warner; David LaHart; Jill D. Wright (1993). Human Biology and Health. Englewood Cliffs, New Jersey, USA: Prentice Hall. ISBN 0-13-981176-1.
  2. ^ Pocock, Gillian (2006). Human Physiology (Third ed.). Oxford University Press. p. 382. ISBN 978-0-19-856878-0.
  3. ^ Cassidy, Suzanne B.; Dykens, Elisabeth; Williams, Charles A. (2000). "Prader-Willi and Angelman syndromes: Sister imprinted disorders". American Journal of Medical Genetics. 97 (2): 136–46. doi:10.1002/1096-8628(200022)97:2<136::AID-AJMG5>3.0.CO;2-V. PMID 11180221.
  4. ^ Susan Standring (editor in chief) (2008). Gray's anatomy : the anatomical basis of clinical practice (40th ed.). [Edinburgh]: Churchill Livingstone/Elsevier. ISBN 978-0443066849.
  5. ^ Lindhe, Jan; Lang, Niklaus P; Karring, Thorkild, eds. (2008) [2003]. Clinical Periodontology and Implant Dentistry 5th edition. Oxford, UK: Blackwell Munksgaard. p. 48. ISBN 9781405160995.
  6. ^ Lindhe, Jan; Lang, Niklaus P; Karring, Thorkild, eds. (2008) [2003]. Clinical Periodontology and Implant Dentistry 5th edition. Oxford, UK: Blackwell Munksgaard. ISBN 9781405160995.
  7. ^ Nascimento WV1, Cassiani RA, Dantas RO., 2012, "Gender effect on oral volume capacity", Dysphagia, 27(3):384-9.

External links

  • Media related to Mouths at Wikimedia Commons
  • Quotations related to Mouths at Wikiquote
Alveolar ridge

The alveolar ridge (; also known as the alveolar margin) is one of the two jaw ridges, extensions of the mandible or maxilla, either on the roof of the mouth between the upper teeth and the hard palate or on the bottom of the mouth behind the lower teeth. Most of the roof of one's mouth is the hard palate and the soft palate. The alveolar ridges contain the sockets (alveoli, singular "alveolus") of the teeth. They can be felt with the tongue in the area right above the top teeth or below the bottom teeth. Its surface is covered with little ridges.

The [upper] alveolar ridge is a small protuberance just behind the upper front teeth that can easily be felt with the tongue.

Consonants whose constriction is made with the tongue tip or blade touching or reaching for the alveolar ridge are called alveolar consonants. Examples of alveolar consonants in English are, for instance, [t], [d], [s], [z], [n], [l] like in the words tight, dawn, silly, zoo, nasty and lurid. There are exceptions to this however, such as speakers of the New York accent who pronounce [t] and [d] at the back of their top teeth (dental stops). When pronouncing these sounds the tongue touches ([t], [d], [n]), or nearly touches ([s], [z]) the upper alveolar ridge, which can also be referred to as gum ridge. In many other languages, consonants transcribed with these letters are articulated slightly differently, and are often described as dental consonants. In many languages consonants are articulated with the tongue touching or close to the upper alveolar ridge. The former are called alveolar plosives (such as [t] and [d]), and the latter alveolar fricatives (such as [s] and [ʃ]).

Cementoenamel junction

The cementoenamel junction, frequently abbreviated as the CEJ, is a slightly visible anatomical border identified on a tooth. It is the location where the enamel, which covers the anatomical crown of a tooth, and the cementum, which covers the anatomical root of a tooth, meet. Informally it is known as the neck of the tooth. The border created by these two dental tissues has much significance as it is usually the location where the gingiva attaches to a healthy tooth by fibers called the gingival fibers.

Active recession of the gingiva reveals the cementoenamel junction in the mouth and is usually a sign of an unhealthy condition.

There exists a normal variation in the relationship of the cementum and the enamel at the cementoenamel junction. In about 60–65% of teeth, the cementum overlaps the enamel at the CEJ, while in about 30% of teeth, the cementum and enamel abut each other with no overlap. In only 5–10% of teeth, there is a space between the enamel and the cementum at which the underlying dentin is exposed.

Cementum

Cementum is a specialized calcified substance covering the root of a tooth. The cementum is the part of the periodontium that attaches the teeth to the alveolar bone by anchoring the periodontal ligament.

Crown (tooth)

In dentistry, crown refers to the anatomical area of teeth, usually covered by enamel. The crown is usually visible in the mouth after developing below the gingiva and then erupting into place. If part of the tooth gets chipped or broken, a dentist can apply an artificial crown.

Crowns are used most commonly to entirely cover a damaged tooth or cover an implant. Bridges are also used to cover a space if one or more teeth is missing. They are cemented to natural teeth or implants surrounding the space where the tooth once stood.

There are various materials that can be used including a type of cement or stainless steel. The cement crowns look like regular teeth while the stainless steel crowns are silver or gold.

FDI World Dental Federation notation

FDI World Dental Federation notation is a dental notation widely used by dentists internationally to associate information to a specific tooth.Developed by the FDI World Dental Federation, World Dental Federation notation is also known as ISO 3950 notation.

Orientation of the chart is traditionally "dentist's view", i.e. patient's right corresponds to notation chart left. The designations "left" and "right" on the chart below correspond to the patient's left and right.

Facial nerve

The facial nerve is the seventh 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 sensations from the anterior two-thirds of the tongue. The nerves typically travels from the pons through the facial canal in the temporal bone and exits the skull at the stylomastoid foramen. It arises from the brainstem from an area posterior to the cranial nerve VI (abducens nerve) and anterior to cranial nerve VIII (vestibulocochlear nerve).

The facial nerve also supplies preganglionic parasympathetic fibers to several head and neck ganglia.

The facial and intermediate nerves can be collectively referred to as the nervus intermediofacialis.

Gums

The gums or gingiva (plural: gingivae), consist of the mucosal tissue that lies over the mandible and maxilla inside the mouth. Gum health and disease can have an effect on general health.

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 alveolar arch formed by the alveolar process that holds the upper teeth (when these are developed).

Incisive foramen

In the human mouth, the incisive foramen, also called anterior palatine foramen, or nasopalatine foramen is a funnel-shaped opening in the bone of the oral hard palate immediately behind the incisor teeth where blood vessels and nerves pass. The incisive foramen is continuous with the incisive canal, this foramen or group of foramina is located behind the central incisor teeth in the incisive fossa of the maxilla.

The incisive foramen receives the nasopalatine nerves from the floor of the nasal cavity along with the sphenopalatine artery supplying the mucous membrane covering the hard palate of the mouth.

In many other species, the incisive foramina allow for passage of ducts to the vomeronasal organ.

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 an erogenous zone when used in kissing and other acts of intimacy.

Mandibular central incisor

The mandibular central incisor is the tooth located on the jaw, adjacent to the midline of the face. It is mesial (toward the midline of the face) from both mandibular lateral incisors. As with all incisors, its function includes shearing or cutting food during mastication, commonly known as chewing. There are no cusps on the tooth. Instead, the surface area of the tooth used in eating is called an incisal ridge or incisal edge. Though the two are similar, there are some minor differences between the deciduous (baby) mandibular central incisor and that of the permanent mandibular central incisor. The mandibular central incisors are usually the first teeth to appear in the mouth, typically around the age of 6-8 months.

Neonatal teeth

Natal teeth are teeth that are present above the gumline (have already erupted) at birth, and neonatal teeth are teeth that emerge through the gingiva during the first month of life (the neonatal period).The incidence of neonatal teeth varies considerably, between 1:700 and 1:30,000 depending on the type of study; the highest prevalence is found in the only study that relies on personal examination of patients.Natal teeth, and neonatal teeth, can be the baby's normal deciduous teeth, sprouting prematurely. These should be preserved, if possible. Alternately, they could be supernumary teeth, extra teeth, not part of the normal allotment of teeth.

Periodontium

The periodontium is the specialized tissues that both surround and support the teeth, maintaining them in the maxillary and mandibular bones. The word comes from the Greek terms περί peri-, meaning "around" and -odont, meaning "tooth". Literally taken, it means that which is "around the tooth". Periodontics is the dental specialty that relates specifically to the care and maintenance of these tissues. It provides the support necessary to maintain teeth in function. It consists of four principal components, namely:

Gingiva

Periodontal ligament (PDL)

Cementum

Alveolar bone properEach of these components is distinct in location, architecture, and biochemical properties, which adapt during the life of the structure. For example, as teeth respond to forces or migrate medially, bone resorbs on the pressure side and is added on the tension side. Cementum similarly adapts to wear on the occlusal surfaces of the teeth by apical deposition. The periodontal ligament in itself is an area of high turnover that allows the tooth not only to be suspended in the alveolar bone but also to respond to the forces. Thus, although seemingly static and having functions of their own, all of these components function as a single unit.

The Wnt signaling antagonist Sfrp3/Frzb has been recently discovered as an early developmental marker of the periodontium.

Retromolar space

The retromolar space or retromolar gap is a space at the rear of the mandible, between the back of the last molar and the anterior edge of the ascending ramus where it crosses the alveolar margin.

This gap is generally small or absent in modern humans, but it was more often present in Neanderthals, and it was common among some prehistoric Amerindians, such as Arikara and Mandan.

Root canal

A root canal is the naturally occurring anatomic space within the root of a tooth. It consists of the pulp chamber (within the coronal part of the tooth), the main canal(s), and more intricate anatomical branches that may connect the root canals to each other or to the surface of the root.

Soft palate

The soft palate (also known as the velum, palatal velum, or muscular palate) is, in mammals, the soft 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 the hard palate. The soft palate is distinguished from the hard palate at the front of the mouth in that it does not contain bone.

Universal Numbering System

The Universal Numbering System also called the "American System", is a dental notation system for associating information to a specific tooth used in the United States.

In the rest of the world, a different International Standard (DIN EN) ISO 3950:2016 is used.

White roll

White roll is the white line that borders the top of the upper lip. It's an adnexal mass of specialized glands and fat. White roll occurs naturally for nearly everyone, although it can be not white and less visible for dark skinned individuals. Well defined white roll indicates youthfulness and is considered aesthetically pleasing.With age, white roll often becomes less defined. This is due to sun damage, changes in facial fat, and decreasing collagen in the area right above the lip. White roll can also be accentuated using injectable fillers.Sometimes white roll is absent or damaged, due to trauma or cleft lip, in which case it could be reconstructed with plastic surgery. However, it is difficult to achieve satisfactory results using surgery, because malalignment of even a milimeter is noticable and unattractive. It is therefore sometimes tattood instead.

Wisdom tooth

A wisdom tooth or third molar is one of the three molars per quadrant of the human dentition. It is the most posterior of the three. The age at which wisdom teeth come through (erupt) is variable, but generally occurs between late teens and early twenties. Most adults have four wisdom teeth, one in each of the four quadrants, but it is possible to have none, fewer, or more, in which case the extras are called supernumerary teeth. Wisdom teeth may get stuck (impacted) against other teeth if there is not enough space for them to come through normally. While this does not cause movement of other teeth, it can cause tooth decay if the impaction makes oral hygiene difficult. Wisdom teeth which are partially erupted through the gum may also cause inflammation and infection in the surrounding gum tissues, termed pericoronitis. Wisdom teeth are often extracted when or even before these problems occur. However some recommend against the prophylactic extraction of disease-free impacted wisdom teeth.

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