|Head and neck.|
|A closed human mouth|
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. 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. Another non-digestive function of the mouth is its role in secondary social and/or sexual activity, such as kissing. The physical appearance of the mouth and lips play a part in defining sexual attractiveness.
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 swallows food and drinks that then go down the esophagus and into the stomach.
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 practiced by females. Both men and women, however, apply lip balm in order to soothe chapped or dry lips.
Piercings in or around the mouth have been made popular by the younger generations. Piercings on the lip or tongue are not uncommon. The uvula piercing is also making a greater appearance, though it still remains a relatively rare piercing and there are still many piercers who refuse to do it.
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.
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.
The mouth is the entry point for our nutrition. The most obvious function is to masticate, or chew, food to a size and texture able to pass through the esophagus to the stomach. Many more things happen in the mouth. Saliva contains enzymes that begin to break down food. The nerves of the brain send signals to the rest of the digestive tract to prepare for digestion. Both fluids and chewed foods have to be passed to the back of the throat and into the esophagus without blocking the breathing tube (the trachea).
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