Anatomy of the upper and lower jaws of a person. Their structure and functions.
Content
Jaws are part of a person’s facial skeleton. Between themselves, the upper and lower jaws, at the level of the skeleton, are not connected and they are connected only by soft tissues.
Schoolchildren are often mistaken, claiming that the upper and lower jaw unites the joint. But in reality The lower jaw is connected by a joint with the temporal boneand this joint is called landing-nomadol.
The lower jaw of a person - The only mobile bone in the skull of man. And the joint that provides this mobility is special, it provides movement at once in three directions: vertical movements (opening and closing the mouth), horizontal movements (moving the lower jaw from side to side), and extending the lower jaw forward.
The upper jaw of a person, from the point of view of anatomy, much larger in the area where the upper teeth grow. The upper jaw ends only in the area of \u200b\u200bthe bridge of the nose, where it is motionless with the frontal bone. It turns out that the bones of the face that surround the nose to the nose and the inner corners of the eyes, all this is the upper jaw. In the scientific language, the upper jaw has four processes: alveolar (where the teeth grow), frontal, zygomatic and non -tone, forming our solid sky.
The upper jaw of a person is considered an air bone, since it is located in it the sinuses, anatomically, these cavities in the bones are lined with epithelium. This epithelium is ciliated, that is, it provides the movement of air inside the sinus, also in it there are glands releasing mucus.
It is interesting that scientists are still not completely clear why a person needs the sinus sinus, some say that they are needed to warm and moisturize air, others express a hypothesis, that they have an entire internal laboratory of the body where he studies microbes that fall into them From the environment.
Blood circulation and sensitivity in human jaws
In the lower jaw of a person there is a jaw canal, an elongated narrow cavity along which the mandibular artery, vein and the mandibular nerve pass. In the upper jaw there is also the maxillary artery, vein and nerve, but their structure, as can be seen in the figure below, is more branched.
These vessels and nerves provide nutrition and sensitivity to the teeth, but not only them, they also are responsible for the sensitivity of the soft tissues of the face and partially provide blood circulation in them.
If you look at the drawing, it becomes clear why half of the jaw, and sometimes the floor of the face, can hurt at once due to one sore tooth. All these areas unites trigeminal nerve.
Nature took care that the facial nerve reliably protect bone tissues. But its damage is dangerous, because they can lead to loss of sensitivity and immobilization of part of the face.
Through the chin hole A bunch of nerves and blood vessels comes out of the body of the jaw into soft tissue. As a rule, the chin hole is located between 4 and 5 tooth, but in different people its location may vary slightly.
About blood circulation in the human jaws can be said that the upper and lower jaw arteries are branches of the carotid artery. And venous blood from the jaws subsequently finds himself in a jugular vein.
Functions of the upper and lower jaw of a person
- Support function. The upper and lower jaw of a person serve as a support for facial and chewing muscles. And there are many muscles, according to some reference books only on the face of a person of 57 individual muscles.
- Protective function. The bones of the jaws are protected by the senses and the upper parts of the digestive system.
- Digestion. Jaws are necessary to bite and chew food. In addition, some muscles necessary for the implementation of sucking and swallowing movements are attached to them.
- Breath. The jaws serve as a container and a support for the upper respiratory tract, in which the air is filtered, moistened and heats up.
- Speech. The jaws are involved in the process of articulation. Regulation of the opening of the mouth with a temporous-nominal joint, the presence of teeth, the work of muscles attached to the jaws-all this is necessary to make our speech intelligible.
- Facial expressions and communication. The mobile lower jaw and facial muscles are necessary in order to reproduce emotions understandable to other people and communicate with the outside world.
Interesting: mouth is the most developed part of the baby's body. It is there that the most sensitive nerve endings are located and therefore small children, to explore the subject, pull it into their mouths.
The structure and functions of the upper and lower jaw: how many teeth in humans?
How many teeth do a person have? From nature, an adult should have from 28 to 32 teeth (with wisdom teeth). It is interesting that 8 teeth or teeth of wisdom have not everyone, some people grow only 3 or 2 wisdom teeth, and the rest do not grow at all. In addition, wisdom teeth are often incompletely developed, with one root, with weak enamel.
Scientists consider the teeth of wisdom atavism, they say that their presence is not necessary, and over time, wisdom teeth grow in less and fewer people. There is also a tendency to reduce the size of the human jaws. For example, the Neanderthal's brain was much smaller, and the jaw is much larger than that of a modern person, the tendency to change the size of these organs is maintained now.
By nature, a person should have 28 teeth, but sad statistics are such that the presence of such a number of teeth is rather an exception than the rule.
Interesting: according to statistics, 14% of the population of Russia is completely toothless. And the average resident of the Russian Federation, who has only 12 teeth over 65 years old.
Statistics proves a direct relationship between the income level of citizens and the number of teeth in their old age. Over time and the development of dentistry, people are increasingly managing to keep their teeth until old age. So, according to Danish sociologists in 1975, in their country, there were 25% of the adult population completely toothless, and now this figure is 5 times lower.
Video: Anatomy of the lower jaw
