mouth

mouth

[n. mouth; v. mouth]
mouth, entrance to the digestive and respiratory tracts. The mouth, or oral cavity, is ordinarily a simple opening in lower animals; in vertebrates it is a more complex structure. In humans, the mouth is defined in front and at the sides by the lips, jawbone, teeth, and gums; in the rear it merges with the throat. The roof of the mouth is composed of the hard and soft palates and the floor of the mouth is formed by the tongue, a muscular structure that contains the organs of taste (taste buds). The lips, palates, tongue, and teeth are the major components in speech formation, using the "raw sound" formed in the larynx. The process of digestion begins in the mouth; the chewing and grinding action of the teeth reduces the food to a readily digestible substance. The enzymatic process of converting starch to sugar is initiated by salivary amylase (ptyalin) excreted by the three salivary glands located at the angle of the jawbone and under the tongue. Saliva produced in these glands moistens food, preparing it for processing in the digestive system.
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 solid food particles into smaller pieces and mixing them with saliva. It is lined with a mucous membrane (as opposed to the exterior of the body, which is lined with skin. The lips mark the transition from mucous membrane to skin.

In humans

Mouth cavity

The first space of the mouth is the mouth cavity, bounded laterally and in front by the alveolar arches (containing the teeth), and posteriorily by the isthmus of the fauces. The oral cavity is also known as the mouth which it swallows food and drinks and goes down to the person's stomach.

Function

The mouth plays an important role in speech (it is part of the vocal apparatus), facial expression, kissing, eating, drinking (especially with a straw) & breathing.

Infants are born with a sucking reflex, by which they instinctively know to suck for nourishment using their lips and jaw.

Cultural aspects

According to western etiquette, the mouth is kept closed, especially when chewing.

Lips can be adorned with lipstick or lip gloss, although in most cultures this is typically only practised by females.

Piercings have been made popular by the younger generations. Lip, tongue, and the 'Monroe' (Monroe piercing is a stud piercing placed on one's face in the same area as Marilyn Monroe's well known and prominent birthmark was) are piercings seen in many varieties. Piercings of any sort besides two subtle earrings are seen as rebellious to the norm in many western cultures.

Development

The philtrum is the vertical groove in the upper lip, formed where the nasomedial and maxillary processes meet during embryo development. When these processes fail to fuse fully, a hare lip and/or cleft palate 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.

In animals

Some animal phyla, including vertebrates, have a complete digestive system, with a mouth at one end and an anus at the other. Which end forms first in ontogeny is a criterion used to classify animals into protostome and deuterostome. The first space of the mouth is the mouth cavity, bounded laterally and in front by the alveolar arches (containing the teeth), and posteriorly by the isthmus of the fauces.

See also

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References

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