Anatomy of the lower jaw of a person. Topographic anatomy of the upper and lower jaw teeth

Among the most important organs of the human body are teeth. Each of them has a certain structure and performs a specific function. What teeth is the upper dentition? What is the anatomy of the lower jaw? In these and other issues related to the structure of the teeth, we have to figure it out.

General information about teeth

An adult in the oral cavity can normally have 28 to 32 teeth. They are special formations with a complex structure. The visible part of each tooth is called the crown. One of its layers is dentin - a solid calcified material that does not have blood vessels. Above it is covered with tooth enamel. It functions as an external protective shell.

The latent part of the tooth is the root. It is placed in the recess of the jawbone, called the alveolus. In the root, too, is dentin. It is covered by a layer of cement, due to which the tooth is held in the recess of the jaw. Inside the bone formation there is a pulpar cavity consisting of nerves, vessels and soft connective tissue.

Types and functions of teeth

The anatomy of the lower jaw and upper jaw subdivides the bone formations located in the oral cavity into several varieties:

• Large molars (molars);
• Front (incisors);
• Conical (fangs);
• Small indigenous (premolars).

Teeth perform several important functions. First, they provide mechanical processing of food. Thanks to the teeth people can fully eat food. Secondly, these bone structures participate in the formation of speech. With their help, different sounds are formed. Third, teeth are part of a smile. They play an important aesthetic role.

Also it is possible to allocate the functions peculiar to each concrete tooth. Cutters located in the frontal part of the oral cavity provide cutting of food. This is facilitated by their flat chisel-shaped crown. Fangs perform the function of crushing and grasping food, since they have a pointed conical shape. Molars and premolars participate in the grinding of food, because their surface is wide enough.

Location of teeth on jaws

The anatomy of the lower jaw and upper dentition shows that the bony formations are arranged in the form of arches, each of which can be divided into 2 sides (quadrant). One quadrant in an adult consists of 8 teeth:

• 3 molars;
• 2 incisors;
• 1 canine;
• 2 premolars.

In some people, the molars, which are last in the dentition and are called "wisdom teeth," are absent. In each quadrant, not 8, but 7 bone formations are obtained. The absence of "wisdom teeth" is absolutely normal. In some people, they erupt to 24-26 years and require removal due to growth at the wrong angle, while others do not appear at all.

Upper molars

As the anatomy of the upper and lower jaw shows, the most complex morphological units of the dentoalveolar system of man are molars. They are in the dental arch behind small molars. On the upper jaw there are 6 molars - 3 teeth each on one side and the other. Specialists distinguish the first, second and third large molars.

The largest tooth among large molars is the first upper molar. He is three-rooted. The surface of the molar, facing the teeth of the opposite row, can be square or diamond-shaped in shape. There are 4 hillocks on it (all the following elevations are divided by furrows):

• Distal-palatine;
• Distal-buccal;
• Medial-buccal;
• Medial-palatine.

The second upper molar differs from the first by the chewing surface. On it, 30-40% of people have 3 tubercles. In 5% of cases, there is a two-tubercular upper molar. As a rule, the tooth has 3 roots. Sometimes 2 of them grow together.

The third upper molar has the shortest crown. The chewing surface may be three-tubercular. In some people this tooth has 4 tubercles. Two-tubercular form is extremely rare. A molar can have 2 and 3 roots. Sometimes their fusion occurs.

Lower molars

The difference between the lower large molars and the upper molars is primarily in the form of a crown. It can be rectangular or pentagonal. Another distinguishing feature of the lower molars from the upper molars is the number of roots. Bony formations located below, there are 2 roots.

The anatomy of the molars of the lower jaw is as follows:

1. On the first molar there is distal, distal-lingual, distal-buccal, medial-lingual and medial-buccal tubercles.
2. The next large molar tooth does not have a distal tubercle. Crown has a four-tubercular appearance.
3. The third molar, which is the smallest of the large molars of the lower jaw, in 50% of people has 4 tubercles, 40% - 5. Much less common is a three- or six-tubercular chewing surface.

Upper incisors

Bony formations that are in the anterior part of the upper jaw and have one root are called upper incisors. Normally there should be 4 teeth - 2 central and 2 laterals. However, more and more often doctors face the primary adentia (absence) of the upper lateral incisors. In ancient times people were eating solid food. In the biting off of the meal, both the central and lateral incisors took part. Currently, people eat more soft foods. Now for biting off food, the strength of the central incisors is sufficient. Lateral teeth bear minimal load. In connection with this, their reduction is observed.

Crown at the central incisors wide. In the medio-distal direction, its width is about 8-9 mm. As for the vestibular surface, it should be noted that it has different types of upper incisors. The anatomy of the lower jaw and upper dentition indicates that:

• The central upper teeth may have the form of a rectangle, a triangle;
• In some people the appearance of the upper incisors is barrel-shaped;
• The upper lateral teeth, as a rule, have a triangular or barrel shape.

The palate surface of the upper incisors can be flat, uniformly concave, shovel-shaped (scoopy). Its appearance depends on the degree of development of the medial and distal marginal ridges extending from the base of the crown to the corners of the cutting edge of the teeth. The incisal edge of unbroken incisors has bends - denticles and tubercles. This waviness disappears as the teeth function in the oral cavity.

Lower incisors

The smallest teeth in the mouth, as shown by the topographic anatomy of the lower jaw, are the lower incisors. They are much inferior in size to incisors, located in the upper dentition. This is due to the fact that in the process of eating food the lower teeth perform auxiliary functions.

On the lower jaw are 4 incisors - 2 central and 2 lateral. Central teeth can have an ovoid or rectangular vestibular surface. In lateral incisors, it has the form of an isosceles triangle, which has a base in the region of the cutting edge and a vertex where the tooth's neck is located.

The lingual surface of the lower incisors is smooth, concave. The form is triangular. On the edges of the lingual surface of the lower teeth pass the distal and medial marginal ridges. They are less developed than on the upper incisors. In recently cut teeth, the incisal edge is tortuous. Bumps are clearly visible. Gradually they disappear. The cutting edge becomes even.

Upper canines

Topographical anatomy of the teeth of the upper and lower jaws includes the study of the structure of canine teeth. These are large bone formations of the dentoalveolar system, having one powerful and long root and a single-hump crown. This structure of the upper teeth is due to the functions performed by them.

The upper canines are located at the points of the bend of the upper dental arch from front to back. The vestibular surface of the crown is characterized by a rhomboid shape. It is the median cushion, also called the central mamelon. In some people it is well marked, and in others it is barely expressed. The middle roller terminates in a tearing mound, which is a distinctive feature of the canine teeth. On the edges of the crown also pass the lateral mamelons - medial and distal. They form the lateral edges of the hillock.

The palatal surface of the canines is slightly convex and relief. In the cervical region a small tubercle is visible. From it in the direction of the main hill there is a medial crest. On the sides, you can distinguish between the distal and medial marginal ridges. They stretch from the corners of the crown to the palatal tubercle.

Lower fangs

A narrower and elongated crown, a smaller massiveness are characteristics that distinguish the lower canines from the upper ones. However, the structure of the teeth is similar. If you compare the canines of the lower and upper jaws, you can see that the crown has a rhomboid shape. Only here in the lower teeth, the top of the rhombus in the region of the torn bump is more flattened, truncated.

Most people seem to have a convex canine of the lower jaw. Anatomy explains this by the fact that the median cushion passing through the vestibular surface is well expressed. Lateral rollers, as a rule, are less noticeable. However, in some people the vestibular surface of the teeth has a flattened shape. In such cases, the median cushion is less pronounced.

The relief of the lingual surface of the lower canine teeth is rather scarce. On it in the cervical region there is a lingual tubercle. It fuses seamlessly with the main crest, terminating in the middle third of the lingual surface. On the edges of the crown are visible marginal ridges.

Top premolars

On the upper jaw, a person has 4 premolars - 2 small molars on each side. They are located in the middle part of the dental arch, occupying the 4th and 5th positions. Premolary, as evidenced by the anatomy of the teeth of the upper and lower jaw, perform an auxiliary function in the process of mechanical processing of food. They crush and crush the food they eat.

Distinguish between the first and second upper premolars. The first small molars, having a crown of a prismatic shape, can be two-or one-root. On the chewing surface there are 2 tubercles - buccal and palatine. The first of these is, as a rule, larger and taller. Between them there is a mezhbugorkovaya furrow. There are edge ridges along the edges of the crown.

The second upper premolar has almost the same structure. There are only a few distinguishing characteristics:

• The tooth, as a rule, has one root canal and one root;
• The relief of the crown is more smooth;
• Chewing tubercles have practically the same height;
• Lateral ridges are underdeveloped.

Lower premolars

Lower small molars, in contrast to the upper molars, are smaller, have a longer solitary root and a rounded crown in a horizontal section. People who know the anatomy of the teeth of the lower jaw, distinguish between the first and second lower premolars, slightly different in structure.

The first one has similarities to the canine. These teeth have similar crowns. However, in the small molar, unlike the canine, there are 2 tubercles on the masticatory surface. The first of these is called the buccal, and the second is called lingual. Separate the tubercles between the tubercle groove. In many people it is interrupted by a medial transverse comb.

The second small molar, as evidenced by the anatomy of the man's lower jaw, is slightly larger than the first. Chewing surface is two-tubercular. Sometimes 3 or even 4 tubercles come to light. On the surface of the small molar there is a deep transverse furrow with terminal branches. The root of the second premolar is longer than the first.

Thus, the teeth that make up the upper and lower jaw, the structure, the anatomy of these elements is a complex but interesting topic. Each bone formation is constructed from special tissues, has its own blood vessels and a nervous apparatus. The structure of the teeth is rather difficult, because it depends on the functions they perform.