| This contest is fueled by the following news: |
| |
Mouth, or oral cavity, front part of digestive tract, starts from oral fissure and ends at pharynx (if it is absent – ends straight at esophagus). Mouth in animals develops wholly or partially by invaginating ectoderm - from foregut.
Oral cavities of invertebrates are often associated with special attachments: splitting and cutting formations in free-living nemathelminthes, jaws of gasteropodas and squids (cephalopodas) and oral parts in arthropoda. mouth of vertebrates is paved with multilayered, sometimes cornified epithelial tissue. Fish and terrestrial vertebrates have jaws (teeth) at front and sides, muscular bed from below where hyoid arch is hidden in its depths, and plays role of tongue many animals. Roof of mouth in fish and amphibians is strengthened by bones of basis cranii which form so called primary palate and postnaris which open immediately in mouth. Amniotes have their mouth divided into upper (breathing) and lower (secondary mouth) parts by means of extended hard palate. From its backend in mammals goes soft palate, which divides oral cavity and pharynx. Bird’s palate and also very often mammals have papilla, cross cushions or palatine scutes covered with keratinous coating and they help in grinding food. Keratinous layer of these cushions in edentate whales grows rapidly and later takes shape of baleen.
Mammals, because of growth in soft flexible labia between jaws and teeth, have a cavity, so called threshold of oral cavity. Threshold of mouth of several mammals form side projections – cheek pouches. Mammals and humans have tongue, teeth and mouth glands located in their mouth.
Human’s mouth topographically divided into front part, or entrance of mouth derivative of oscular bay, and back part, or cavity of mouth itself (pic.). Lips at front, cheeks at sides, alveolar appendages of upper and lower jaws and teeth are boundaries of mouth. Oral cavity itself is limited by fornix of upper and lower palate at the top, below located is mucous membrane covering muscles and root of tongue, fundus of mouth, at front and sides civered by internal surface of alveolar oppendages of upper and lower jaws and teeth. mouth at front is connected with outdoor environment by means of oral opening, fauces at the back is connected with pharynx. Here located are lymphoepithelioma organs – tonsils. In depths of mucous membrane there are many small salivary glands. Emunctory canals of big salivary glands (parotid, hyoid, submandibular) are also opened in mouth. Blood circulation, chyle efflux and innervation of walls of mouth is closely linked with vascular and nervous systems of jaws. Gustatory organs and receptors are located in mucous membrane. Constant bacteria population is maintained in mouth which serves as biological barrier for microbes, and also located there is flora. mouth takes participation in the processes of: digesting food, breathing, formation of voice and acts of speech. See. also mastication, suction.
Diseases of mouth: Gingivitis, stomatitis, dental deceases, deceases of jaws, tongue, lips, salivary glands (see. Sialolthiasis) smokers patch, papilloma and others. |
|
When it comes to horror images, one of the most disturbing depictions of human face is with mouths in the place of eyes - such illustrations are favorite of many horror books.
