Functions and structure of the oral cavity
The mouth of any living being is the most complicatedbiomechanical system, providing him with food, and hence, existence. In higher organisms, the mouth, or, to put it scientifically, the oral cavity, carries an additional important burden - sound production. The structure of the human oral cavity is the most complex, which was influenced by communication functions and a number of features related to the development of the human body.
Structure and function of the oral cavity
In all living organisms, including humans, the mouthis the first department of the digestive system. This is his most important and common for most creatures function, no matter what form he came up with nature. In humans, it is a gap that can open wide. With the mouth we grab or take food, hold it, crush it, moisten it with plenty of saliva, and push it into the esophagus, which in fact is a hollow tube through which food slips into the stomach for processing. But the beginning of digestion begins already in the mouth. That is why the ancient philosophers said how many times you will spend, you will live for so many years.
The second function of the mouth is the pronunciation of sounds. Man not only publishes them, but also unites them in complex combinations. Therefore, the structure of the mouth cavity in humans is much more complicated than that of our smaller brothers.
The third function of the mouth is participation in the process of breathing. Here it is his job to only take portions of air and transmit them to the respiratory tract, when for some reason this can not be handled by the nose and partly during the conversation.
We daily use all parts of the mouth, and some of them even repeatedly contemplate. In science, the structure of the oral cavity is more or less concretized. The photo clearly shows what it is.
Physicians in this body distinguish two departments, called the vestibule of the mouth and actually its cavity.
In the run-up, there are external organs (cheeks, lips) and internal (gums, teeth). So to speak, the entrance to the mouth is called the oral slit.
The oral cavity itself is a certainspace, on all sides limited by the organs and their parts. Bottom is the bottom of our mouth, the top of the palate, the front of the gums, and also the teeth, behind the tonsils, which are the border between the mouth and throat, from the sides of the cheek, in the center of the tongue. All internal parts of the oral cavity are covered with a mucous membrane.
This body, which pays so much attention tothe weak sex to rule the strong sex, in fact, is the twin muscular folds surrounding the mouth slit. In humans, they participate in the retention of food entering the mouth, in sound formation, in mimic movements. Isolate the upper and lower lips, the structure of which is approximately the same and includes three parts:
- Outer - covered with keratinous planar multilayered epithelium.
- Intermediate - has several layers, the outerof which also horny. It is very thin and transparent. Through it the capillaries perfectly permeate, which causes the pink-red color of the lips. Where the horny skin layer passes into the mucosa, many nerve endings are concentrated (several dozen times larger than at the fingertips), so the lips of the person are unusually sensitive.
- Mucous, occupying the back of the lips. It has many ducts of the salivary glands (labial). It covers its nonkeratinous epithelium.
The mucous lips go into the mucous gum to form two longitudinal folds, called the bridles of the upper lip and the lower one.
The border of the lower lip and chin is the horizontal chin-labial furrow.
The border of the upper lip and cheeks are nasolabial folds.
Between themselves, lips are joined at the corners of the mouth by lip adhesions.
The structure of the oral cavity includes a paired organ, to allknown as cheeks. They are divided into the right and left, each has an external and internal parts. The outer is covered with a delicate, delicate skin, an inner non-coronary mucosa, which passes into the gingival mucosa. Also in the cheeks is a fat body. In infants, it plays an important role in the sucking process, so it is developed significantly. In adults, the fatty body flattenes and shifts back. In medicine he is called the fatty lump of Bish. Cheek muscles are the basis of the cheeks. The gland in the submucosa is small. Their ducts open in the mucous membrane.
This part of the mouth is inherently a septumbetween the oral cavity and the nasal, as well as between the nasal part of the pharynx. The functions of the palate are basically just the formation of sounds. In chewing food it participates slightly, as it has lost clear expression of transverse folds (in infants they are more noticeable). In addition, the palate enters the articulatory apparatus, which provides the bite. Distinguish between the palate and soft.
On a solid accounted for 2/3 of the part. It is formed by the plates of the palatines and the processes of the maxillary bones fused together. If for some reason the splice does not occur, the baby is born with an abnormality called the wolf's mouth. In this case, the nasal and oral cavities are not separated. Without specialized care, such a child dies.
Mucous in normal development should fuse with the upper palate and gently move to the soft palate, and then onto the alveolar processes in the upper jaw, forming the upper gums.
On the soft palate is only 1/3 of the part, but ithas a significant effect on the structure of the oral cavity and pharynx. In fact, the soft palate is a specific fold of the mucous, like a curtain hanging over the root of the tongue. It separates the mouth from the pharynx. In the center of this "curtain" is a small outgrowth called a tongue. It helps to form sounds.
From the edges of the "curtain"(palate-lingual) and posterior (palate-pharyngeal). Between them there is a fossa where the accumulation of cells of lymphoid tissue (palatine tonsil) is formed. At 1 cm from it is located carotid artery.
This body performs many functions:
- chewing (in infants sucking);
- perceiving taste.
The shape of a person's tongue is influenced not bystructure of the oral cavity, and its functional state. In the language, a root and a body with a back are selected (the side facing the palate). The body of the tongue crosses the longitudinal groove, and in the place of its connection with the root lies a transverse groove. Under the tongue is a special fold, called a bridle. Near it are the ducts of the salivary glands.
The lining of the tongue is covered by multilayer epithelium,in which taste receptors, glands and lymphomas are located. Upper, tip and lateral parts of the tongue are covered with dozens of papillae, divided into mushroom-shaped, filiform, conical, leaf-shaped, grooved. At the root of the tongue there are no papillae, but there are clumps of lymphatic cells that form lingual tonsils.
Teeth and gums
These two interrelated partsinfluence on the features of the structure of the oral cavity. Teeth in a person begin to develop at the embryo stage. The newborn in each jaw has 18 follicles (10 milk teeth and 8 molars). They are arranged in two rows: labial and lingual. The rule is the appearance of baby teeth, when the baby was 6 to 12 months old. Age, when the norm of the milk teeth fall, even more stretched - from 6 years to 12. Adults should have 28 to 32 teeth. The smaller number negatively affects the processing of food and, as a consequence, the work of the digestive tract, since it is the teeth that play the main role in chewing food. In addition, they participate in the correct sound formation. The structure of any of the teeth (indigenous or dairy) is the same and includes the root, crown and neck. The root is in the dental alveolus, at the end has a tiny hole through which the veins, arteries and nerves pass through the tooth. A person has formed 4 varieties of teeth, each of which has a certain shape of the crown:
- incisors (in the form of a bit with a cutting surface);
- fangs (cone-shaped);
- premolars (oval, has a small chewing surface with two tubercles);
- large root (cubic with 3-5 tubercles).
The cervical teeth occupy a small area between the crown and the root and are covered by the gums. At its core gums are mucous membranes. Their structure includes:
- the interdental papilla;
- Gingival margin;
- alveolar area;
- a mobile gum.
Gum consist of multilayered epithelium and lamina.
They are based on a specific stroma, consisting of a variety of collagen fibers, which ensure a tight fit of the mucosa to the teeth and the proper chewing process.
The structure of the mouth and oral cavity will not be disclosedcompletely, if you do not mention the billions of microorganisms for which, during evolution, the human mouth has become not just a house, but an entire universe. Our oral cavity is attractive for the smallest bioforms, thanks to its following features:
- stable, moreover, the optimum temperature;
- constantly high humidity;
- slightly alkaline medium;
- practically constant availability of nutrients in free access.
Infants are born on light already with microbes inmouth, which there move from the birth canal of women in childbirth for the shortest time, while the newborns pass them. Further colonization moves with astonishing speed, and after a month of germs in the mouth of the child there are several dozen species and millions of individuals. In adults, the number of microbial species in the mouth varies from 160 to 500, and their number reaches billions. Not the least role in such a large-scale settlement is played by the structure of the oral cavity. Only teeth (especially sick and unclean) and almost constantly present on them dental plaque contain millions of microorganisms.
Among them, the prevalence of bacteria, the leader among which are streptococci (up to 60%).
In addition to them, fungi (mainly candida) and viruses live in the mouth.
Structure and function of the oral mucosa
The penetration of pathogenic microbes into the tissues of the oral cavity is protected by the mucous membrane. This is one of its main functions - the first to take on the impact of viruses and bacteria.
It also covers the tissues of the mouth from the effects of unfavorable temperatures, harmful substances and mechanical injuries.
In addition to protective, the mucosa performs another very important function - the secretory one.
Features of the structure of the mucosa of the cavityof the mouth are such that glandular cells are located in its submucosa. Their accumulations form small salivary glands. They continuously and regularly moisturize the mucous membrane, ensuring that it performs protective functions.
Depending on which parts the mucous membrane covers, it can be with a keratinized surface layer or epithelium (25%), with non-keratinizing (60%) and with mixed (15%).
The horny epithelium covers only the solid palate and gums, because they participate in chewing and interact with solid food fragments.
The non-cornificating epithelium covers the cheeks, soft palate, its outgrowth is the tongue, that is those parts of the mouth that need flexibility.
The structure of both of these epithelia includes 4 layers. The first two of them, basal and prickly, are in both.
In cornified the third place is occupied by a granular layer, and the fourth horny (there are cells without nuclei and practically no leukocytes).
In the non-keratinous, the third layer is intermediate, and the fourth layer is superficial. There is an accumulation of leukocyte cells, which also affects the protective functions of the mucosa.
Mixed epithelium covers the tongue.
The structure of the oral mucosa has other features:
- Absence of a muscular plate in it.
- Absence in some parts of the oralcavities of the submucosa base, that is, the mucosa lies directly on the muscles (observed, for example, in the tongue), or directly on the bone (for example, on the hard palate) and firmly fuses with the underlying tissues.
- The presence of multiple capillaries (this gives the mucous characteristic reddish color).
Structure of the oral cavity in children
During the life of a person the arrangement of his organschanges. Thus, the structure of the oral cavity of children up to a year differs significantly from its structure in adults, and not only by the absence of teeth, as mentioned above.
The primary mouth of the embryo is formed on the secondweek after conception. In newborns, as everyone knows, there are no teeth. But this is not the same as the absence of teeth in the elderly. The fact is that in the oral cavity of babies teeth are in the state of rudiments, and, simultaneously, both dairy and permanent. At some point they will appear on the surface of the gums. In the oral cavity of the elderly, the alveolar processes themselves are already atrophied, that is, there are no teeth and will not.
- Soft lips with a specific lip pillow.
- A relatively well developed circular muscle in the mouth.
- The gingival membrane with a lot of tubercles.
- Transverse folds in the solid palate are clearly defined.
- The position of the lower jaw is distal (the baby pushes his lower jaw, and makes it back and forth, not to the sides or in a circular manner, as in chewing).
An important feature of babies is that they can swallow and simultaneously breathe.
Structure of the oral mucosa of infantsalso different from adults. Epithelium in children under one year consists only of basal and spine-like layers, and the epithelial papillae are very poorly developed. In the connective layer of the mucosa there are protein structures transmitted from the mother along with immunity. Adulthood, the baby loses its immune properties. This also applies to the tissues of the oral mucosa. Later, the epithelium thickens in it, the amount of glycogen on the hard palate and gums decreases.
By the age of three, the oral mucosa has moreclear regional differences, the epithelium acquires the ability to coronate. But in the connective layer of the mucosa and near the blood vessels there are still many cellular elements. This promotes increased permeability and, as a consequence, the occurrence of herpetic stomatitis.
By age 14, the structure of the oral mucosaadolescents are not much different from adults, but against the background of hormonal changes in the body they can have mucosal diseases: mild leukopenia and juvenile gingivitis.