home Consultations What is the method of connecting bones in a joint. Types of bone connections - joints, ligaments, cartilage. General information about the human skeletal system

What is the method of connecting bones in a joint. Types of bone connections - joints, ligaments, cartilage. General information about the human skeletal system

There are three types of bone joints.

Continuous joints in which there is a layer of connective tissue or cartilage between the bones. There is no gap or cavity between the connecting bones.

Discontinuous joints, or joints (synovial joints), are characterized by the presence of a cavity between the bones and a synovial membrane lining the inside of the joint capsule.

Symphyses, or semi-joints, have a small gap in the cartilaginous or connective tissue layer between the connecting bones (a transitional form from continuous to discontinuous joints).

Continuous bone connections

Continuous connections have greater elasticity, strength and, as a rule, limited mobility. Depending on the type of tissue connecting the bones, three types of continuous connections are distinguished: 1) fibrous connections, 2) synchondrosis (cartilaginous connections) and 3) bone connections.

Fibrous joints are strong connections between bones using dense fibrous connective tissue. Three types of fibrous joints have been identified: syndesmoses, sutures and impactions.

Syndesmosis is formed by connective tissue, the collagen fibers of which grow together with the periosteum of the connecting bones and pass into it without a clear boundary. Syndesmoses include ligaments and interosseous membranes. Ligaments are thick bundles or sheets of dense fibrous connective tissue. For the most part, ligaments spread from one bone to another and reinforce discontinuous joints (joints) or act as a brake that limits their movement. In the spinal column there are ligaments formed by elastic connective tissue that has a yellowish color. Therefore, such ligaments are called yellow. The yellow ligaments are stretched between the vertebral arches. They stretch when the spinal column flexes (flexion of the spine) and, due to their elastic properties, shorten again, promoting extension of the spinal column.

Interosseous membranes, stretched between the diaphyses of long tubular bones. Often, interosseous membranes and ligaments serve as the origin of muscles.

A suture is a type of fibrous joint in which there is a narrow connective tissue layer between the edges of the connecting bones. The connection of bones by sutures occurs only in the skull. Depending on the configuration of the edges of the connecting bones, they are divided into serrated seam, scaly seam, And flat seam. In a serrated suture, the jagged edges of one bone fit into the spaces between the teeth of the edge of another bone, and the layer between them is connective tissue. If the connecting edges of flat bones have obliquely cut surfaces and overlap each other in the form of scales, then a scaly suture is formed. In flat sutures, the smooth edges of two bones are connected to each other using a thin connective tissue layer.

A special type of fibrous connection is impaction . This term refers to the connection of the tooth with the bone tissue of the dental alveolus. Between the tooth and the bone there is a thin layer of connective tissue - periodontium .

Synchondroses , They are connections between bones and cartilage. Such connections are characterized by strength, low mobility, and elasticity due to the elastic properties of cartilage. The degree of bone mobility and the amplitude of springing movements in such a joint depend on the thickness and structure of the cartilaginous layer between the bones. If the cartilage between the connecting bones exists throughout life, then such synchondrosis is permanent. In cases where the cartilaginous layer between the bones persists until a certain age (for example, sphenoid-occipital synchondrosis), this is a temporary connection, the cartilage of which is replaced by bone tissue. Such a joint replaced by bone tissue is called a bone joint - synostosis.

Discontinuous, or synovial, connections of bones (joints)

Synovial joints (joints) are the most advanced types of bone connections. They are distinguished by great mobility and a variety of movements. Each joint includes articular surfaces of bones covered with cartilage, an articular capsule, and an articular cavity with a small amount of synovial fluid. Some joints also have auxiliary formations in the form of articular discs, menisci and articular labrum.

The articular surfaces, in most cases, of articulating bones correspond to each other - they are congruent (from the Latin congruens - corresponding, coinciding). If one articular surface is convex (articular head), then the second, articulating with it, is equally concave (glenoid cavity). In some joints these surfaces do not correspond to each other either in shape or size (incongruent).

Articular cartilage is usually hyaline; in individual joints (temporomandibular) it is fibrous and has a thickness of 0.2-6.0 mm. It consists of three layers (zones): superficial; intermediate, And deep. Cartilage smoothes out unevenness of the articular surfaces of bones and absorbs shocks during movement. The greater the load a joint experiences under the influence of gravity, the greater the thickness of the articular cartilage on the articulating surfaces. Articular cartilage is usually even and smooth; constantly moisturized with synovial fluid, which facilitates movement in the joints. Articular cartilage does not have blood or lymphatic vessels; it is nourished by synovial fluid.

The articular capsule is attached to the articulating bones near the edges of the articular surfaces or at some distance from them; it firmly fuses with the periosteum, forming a closed articular cavity. The capsule has two layers: the outer - fibrous membrane and the inner - synovial membrane. The fibrous membrane is thicker and stronger than the synovial membrane and consists of dense fibrous connective tissue with a predominant longitudinal direction of the fibers. In some places, the fibrous membrane forms thickenings - ligaments that strengthen the joint capsule. These are capsular ligaments if they are located in the thickness of the fibrous membrane of the capsule. Ligaments can be located outside the capsule (without merging with it), then these are extracapsular ligaments. There are also ligaments located in the thickness of the joint capsule between its fibrous and synovial membranes. - intracapsular ligaments. The intracapsular ligaments on the side of the joint cavity are always covered with a synovial membrane. The thickness and shape of the ligaments/depends on the structural features of the joint and the force of gravity acting on it. Ligaments also serve as passive brakes, limiting movement in the joint.

The synovial membrane is thin, covered with flat cells. It lines the inside of the fibrous membrane and continues to the surface of the bone, not covered with articular cartilage. The synovial membrane has small outgrowths facing the joint cavity - synovial villi, which are very rich in blood vessels. These villi significantly increase the surface of the membrane. In places where the articulating surfaces are incogruent, the synovial membrane usually forms synovial folds of greater or lesser size. The largest synovial folds (for example, in the knee joint) have pronounced accumulations of adipose tissue. The inner surface of the articular capsule (synovial membrane) is always moistened with synovial fluid, which is secreted by the synovial membrane and, together with exfoliating cartilage and flat connective tissue cells, forms a mucus-like substance that wets the articular surfaces covered with cartilage and eliminates their friction against each other.

The articular cavity is a slit-like space between the articular surfaces covered with cartilage. It is limited by the synovial membrane of the joint capsule and contains a small amount of synovial fluid. The shape of the articular cavity depends on the shape of the articulating surfaces, the presence or absence of auxiliary formations inside the joint (articular disc or meniscus) or intracapsular ligaments.

Articular discs and menisci are cartilaginous plates of various shapes that are located between articular surfaces that do not fully correspond to each other (incongruent). The disc is usually a solid plate, fused along the outer edge with the articular capsule, and, as a rule, divides the articular cavity into two chambers (two floors). Menisci are non-continuous semilunar-shaped cartilaginous or connective tissue plates that are wedged between the articular surfaces (see “Knee Joint”).

Discs and menisci can shift with movement. They seem to smooth out the unevenness of the articulating surfaces, make them congruent, and absorb shocks and jolts during movement.

The articular lip, located along the edge of the concave articular surface, complements and deepens it (for example, in the shoulder joint). It is attached with its base to the edge of the articular surface, and with its inner concave surface facing the joint cavity.

Synovial bursae are protrusions of the synovial membrane in thinned areas of the fibrous membrane of the joint (see “Knee joint”). The sizes and shapes of synovial bursae vary. As a rule, synovial bursae are located between the surface of the bone and the tendons of individual muscles moving near it. The bags eliminate friction between the touching tendons and bones.

Connection of bones. All the bones in the human body are connected to each other in various ways into a harmonious system - the skeleton. But all the variety of bone connections in the skeleton can be reduced to two main types: continuous connections(fibrous) - synarthrosis And discontinuous connections(cartilaginous and synovial) or joints - diarthrosis.

In continuous joints, bones can be connected to each other by: bone substance ( synostoses), which occurs between the vertebrae forming the sacrum, between some bones of the skull: between the sphenoid and occipital, when the sutures of the bones of the cranial vault heal; cartilage ( synchondrosis) - connections of the vertebrae with each other; fibrous connective tissue ( syndesmoses), for example, open sutures of the cranial vault, connections of the lower ends of both tibia bones. The last type of connection is very common.

Continuous connections of the bones of the cranial vault - sutures - come in several types. When the serrations and teeth of one bone fit into the spaces between the teeth of another, we have serrated seam, when the edge of one bone is somewhat thinned, as if cut obliquely and overlaps the edge of another bone like fish scales - scaly seam. If the edges of the connecting bones are smooth and just adjacent to each other, such a seam is called harmonic. When one of the bones is driven or hammered into the recess of another like a wedge or nail, such a connection is called driven in. The teeth are connected to the jaw bones in this way.

There are also transitional forms of bone joints from fixed to mobile - these are semi-joints or, in other words, hemiarthrosis. In appearance, these are cartilaginous compounds with only a small slit-like cavity inside. An example of such a semi-joint is the pubic fusion between two pelvic bones - the so-called symphysis of the pubic bones.

The most common and perfect form of bone connection is a discontinuous connection (diarthrosis), when the end surfaces of two or more bones are just adjacent to each other, separated by a slit-like cavity, and firmly held together by a connective tissue bag. This connection is called joint(articulatio) or articulation. A person has up to 230 joints.

Types of bone joints(diagram), a - joint; b - syndesmosis (suture); c - synchondrosis; 1 - periosteum; 2 - bone; 3 - fibrous connective tissue; 4 - cartilage; 5 - synovial membrane of the joint capsule; 6 - fibrous membrane of the joint capsule; 7 - articular cartilage; 8 - articular cavity

Joint structure. Joints are the most common type of bone connection in the human body. Each joint necessarily has three main elements: articular surfaces, joint capsule And articular cavity.

Articular surfaces in most joints they are covered with hyaline cartilage and only in some, for example in the temporomandibular joint, with fibrous cartilage.

Bursa(capsule) is stretched between the articulating bones, attached to the edges of the articular surfaces and passes into the periosteum. There are two layers in the articular capsule: the outer - fibrous and the inner - synovial. The articular capsule in some joints has protrusions - synovial bursae (bursae). Synovial bursae are located between the joints and tendons of the muscles located around the joint, and reduce the friction of the tendon on the joint capsule. The joint capsule on the outside of most joints is strengthened by ligaments.

Articular cavity has a slit-like shape, is limited by articular cartilage and the articular capsule and is hermetically closed. The joint cavity contains a small amount of viscous fluid - synovium, which is secreted by the synovial layer of the joint capsule. Synovia lubricates articular cartilage, thereby reducing friction in the joints during movement. The articular cartilages of the articulating bones fit tightly to each other, which is facilitated by negative pressure in the joint cavity. Some joints have auxiliary structures: intra-articular ligaments And intra-articular cartilage(discs and menisci).

1. Fixed connection– this is a connection due to the fusion of bones (pelvic bones) or the formation of sutures (skull bones).

2. Semi-moving connection– bones are connected to each other using cartilage, which provides a certain level of mobility relative to each other (for example, ribs with the sternum, vertebrae with each other).

3. Movable connection- characteristic of most bones and is achieved with the help of a special formation - a joint. There are many types of joints, they generally look like this. The end of one of the bones is convex (the head of the joint), and the other bone is concave (the glenoid cavity). The head of the joint is congruent with the socket, the surfaces of both are covered with a layer of smooth cartilage (to reduce friction). The bones of the joint are covered with a common durable shell of connective tissue - articular capsule. It contains fluid to lubricate and reduce friction. In addition, in the cavity of the joint capsule there is low pressure - 5 - 10 mm Hg (i.e. the bones seem to stick to each other). Outside, the bursa is surrounded by ligaments and muscles attached to it, and passes into the periosteum.

Scull.

One of the most important parts of the skeleton. It protects the brain and sensory organs from external influences and serves as a support for the initial parts of the digestive and respiratory systems, and facial muscles. The skull is conventionally divided into the brain and facial sections, consisting of 23 bones - 8 paired and 7 unpaired.

1. Brain department- a container for the brain. Consists of paired bones – parietal and temporal(the auditory canal passes here); and unpaired bones - frontal, occipital etc. In the occipital bone there is foramen magnum, through which the brain connects to the spinal cord. Also, the occipital bone is connected to the first vertebra of the spine using an ellipsoidal joint, which ensures that the head tilts forward and backward - upward. The floor of the skull is formed by the main bone with numerous openings for nerves and blood vessels.

2. Facial department. Comprises maxillary, nasal, zygomatic,orbital, mandibular sublingual and other bones. Mandibular bone movably connected to temporal bones. Both jaws have cells (alveoli) for teeth.

The bones of the skull are mostly flat, connected to each other by serrated and scaly sutures, except for the mandibular (it is connected by a joint).

Features of the human skull - the ratio of the brain and facial parts is three to one (this is only in humans, which ensures the appropriate size of the brain); The shape of the lower jaw is U-shaped, which ensures the formation of articulate speech.

Skeleton of the torso .

Represented by the skeleton of the spine and chest.

I . Spine consists of 33 – 34 vertebrae, between which there are cartilage pads - discs, this provides the spine with flexibility. Each vertebrae consists of a body, an arch and several processes. There is an opening between the body and the arch; the openings of all vertebrae form the spinal canal, in which the spinal cord. The bodies of the vertebrae are connected to each other. The processes perform a protective function (from mechanical damage), while lightening the mass of the vertebra. I distinguish 5 sections of the spine; the vertebrae of different sections have differences in structure.

1. Cervical region– 7 vertebrae (by the way, like all mammals). First vertebra - atlas, has no body, connected to the skull. Second vertebra - epistropheus, has a tooth-like process on the body that allows the head to turn.

2. Thoracic region– 12 vertebrae. There are pits on the lateral surfaces of their bodies for connection with the heads of the ribs.

3. Lumbar– 5 vertebrae, differing from others in large size. The spinal cord ends at the second lumbar vertebra.

4. Sacral section– 5 vertebrae, which in an adult are fused with each other and with the pelvic bones. This occurs due to the increased load when walking upright.

5. Coccygeal region– 5 (usually 4) vertebrae fused together, which are short bones.

Thus, the bones of the spine are mixed and semi-movably connected.

Features of the human spine. It has an S-shape, i.e. 2 forward bends ( lordosis) – cervical and lumbar, and 2 bends back (kyphosis) – thoracic and sacral. Thanks to them, the center of gravity of the body is moved slightly back, which ensures upright posture and, in addition, shock absorption when walking. The vertebral bodies increase in size from top to bottom.

II . Rib cage.

Consists of 12 thoracic vertebrae, 12 pairs of ribs and sternum. The chest covers and protects from mechanical damage heart, lungs,large blood vessels and esophagus.

Sternum is a flat bone located in front. Ribs They are movably connected to the vertebrae and semi-movably connected to the sternum with the help of cartilage and therefore can move. This is of great importance for breathing. The ribs are curved bony plates and are anatomically divided into three groups:

A ) True ribs– from 1 to 7 pairs, each of them connects directly to the vertebra and sternum.

b) False ribs- from the 8th to the 10th pair, they are connected to the vertebrae, like true ones, but their other ends are not attached to the sternum, but are fused with cartilage to each other and to the cartilage of the lower ribs, forming a costal arch. This arch is semi-movably connected to the sternum.

V) Oscillating ribs– 11 and 12 pairs, their anterior ends do not reach the sternum and end, remaining free in the upper parts of the abdominal cavity.

Features of the human chest: it is laterally compressed and flat (unlike that of mammals), which is an adaptation to upright walking - the center of gravity.

Upper limbs.

They are divided into a girdle of limbs and a free limb.

I . Limb belt located in the torso and consists of two bones:

1. Collarbone– a paired, S-shaped curved bone, anatomically part of the chest (located above the first rib). The function of the clavicle is that it keeps the shoulder joint at some distance from the chest, providing adductive movements of the arm. The joints connect to the scapula and sternum.

2. Spatula– a paired flat bone of a triangular shape adjacent to the posterior surface of the chest, connected to collarbone, provides mobility of the shoulder girdle.

II. Upper free limb(hand), anatomically consists of three sections.

1. Shoulder- part of the arm from the shoulder joint to the elbow. Represented by one long tubular bone - brachial.

2. Forearm- part of the arm from the elbow joint to the wrist joint. In this part of the hand there are two parallel bones - ulnar and radial.

3. Brush, is in turn divided into three sections:

A ) Wrist, consists of 8 short dice (2 rows of 4 dice).

b ) Metacarpus– 5 short tubular bones.

V ) Phalanges of fingers– 14 short tubular bones.

Features of the human hand– greater freedom of movement in the shoulder joint (than in animals); arms are noticeably shorter and weaker than legs; the thumb of the hand is opposed to the other four fingers - it is this anatomical detail that allows the human hand to perform numerous and varied movements in all forms of human labor.

Skeleton of the lower limbs .

Similar to the upper limbs, it also consists of limb belts And free limb (leg).

I . Lower limb girdle (pelvic girdle). Presented pelvis, which consists of three pairs of bones:

A) Ilium- forms, as it were, a bowl - a container for the organs of the abdominal cavity and the pelvic cavity.

b) Ischium.

V) Pubic bone.

The hip joint connects the pelvis to the leg. The pelvic bones finally fuse at 12–14 years in girls and 13–16 years in boys. In women, the pelvis is wider and lower, and all its dimensions are larger than in men. These gender differences are due to the fact that in women the pelvis is the container for the fetus developing in the uterus. Due to the upright posture of humans, the outlet from the pelvis is narrower than that of animals, which worsens the conditions for childbirth.

II. Free lower limb (leg). Just like the hand consists of three sections:

1. Hip– from the hip joint to the knee joint. There's one bone here – femoral, the longest tubular bone in the body. The knee joint in front is covered patella (kneecap) - flat bone.

2. Shin– from the knee to the ankle joint. There are 2 bones here - the tibia in front and the fibula in back.

3.Foot. In turn, it consists of three departments:

A) Tarsus– 7 short bones arranged in 2 rows.

b) Metatarsus – 5 short tubular bones.

V) Phalanges of fingers– 14 short tubular bones.

Features of the human lower extremities: accordingly they are longer and stronger than the arms; The foot has an arch, it provides shock absorption when walking. Impaired arches of the feet – flat feet – have a negative impact on human health.

Age-related features of the formation of the human skeletal system.

During the process of prenatal and postnatal development, the child’s skeleton undergoes complex transformations. The formation of the skeleton begins in the middle of the 2nd month of embryogenesis and continues until 18–25 years of postnatal life. At first, the entire skeleton of the embryo is cartilaginous; ossification is not completed at the time of birth, so there is a lot of cartilage in the skeleton of a newborn, and the chemical composition of the bones is different from the bones of an adult. At this time, the bone contains a lot of organic substances, therefore, it does not have strength and is easily bent under the influence of unfavorable external influences. Intensive thickening of the walls of bones and an increase in their mechanical strength occurs up to 6–7 years. Then until the age of 14 there is no change, and after 14 to 18 years there is an increase again.

Final ossification of the skeleton is completed in women at 17–21 years, in men at 19–25 years, and the bones ossify at different times. For example, vertebrae - by 20 - 25 years, and coccygeal vertebrae even by 30 years; hands – at 6–7 years old, and wrists – at 16–17 years old; lower limbs - by approximately 20 years.

The spine of a newborn is characterized by the absence of any bends. At 3 months, cervical lordosis is formed, at 6 months, thoracic kyphosis, and by the 1st year, lumbar kyphosis. However, until the age of 12, the child’s spine remains elastic and the curves are poorly fixed, which easily leads to curvatures (scoliosis). By the age of 12–13 years, the chest already significantly resembles the chest of an adult

Significant changes occur in the skull. Closing of the fontanelles occurs at 1–2 years, and fusion of the cranial sutures occurs by 4 years. The facial region grows rapidly until puberty.

Thus, in general, the skeleton of children and adolescents is characterized by high elasticity, which is always a threat to its deformation if hygiene standards are violated.

Muscular system.

The main tissue of the muscular system is muscle tissue. In the human body it is represented by three types – striated (skeletal))muscle tissue, smooth muscle tissue and cardiac muscle tissue. The differences between them are as follows:

signs	skeletal		Heart

1.location	Attached to the bones, tongue, 1/3 of the esophagus, anal sphincter.	Walls of internal organs - stomach, intestines	Walls of the heart.

2. fiber shape	Elongated, cylindrical, with blunt ends	Elongated, fusiform, with pointed ends.	Elongated, cylindrical, the fibers branch and merge with each other.
3. number and position of nuclei.	Many cores, all on the periphery.	One, in the center.	Plenty, in the center.
4. Transverse striping.		Absent
5. Speed of contraction			Intermediate
6. Ability to remain in a contracted state.			Intermediate
7. Regulation of contractions	Voluntary, regulated by the somatic nervous system	Involuntary, regulated by the autonomic nervous system	Involuntary, has an autonomous control center.

Structure of skeletal muscles.

They consist of bundles of striated muscle fibers. The muscle is covered with a connective tissue membrane – fascia. Muscles are attached to bones by tendons(only facial muscles with one end to the facial skin). Muscles are capable of contracting and relaxing; the signal for these actions is sent via nerves from the central nervous system. The following muscle groups exist:

1. Synergists– different muscles involved in the same movement, for example, the masseter and temporal muscles are involved in clenching the teeth.

2. Antagonists– muscles involved in opposite movements. For example, when reducing biceps(flexor) the elbow joint bends when triceps(extensor) relaxed and vice versa.

Source of muscle energy– decomposition and oxidation of organic substances.

Age-related features of the development of the muscular system.

In the process of development, the motor qualities of muscles change - speed, strength, agility and endurance, and development is uneven.

1. Speed and agility from 4–5 years old to 13–14 years old they reach adult level, and when playing sports 2 times faster. Thus, until the age of 6–7 years, children are not able to make precise movements in an extremely short time. This improves until age 17.

2. Force Maximum growth occurs from 10–12 years in girls and up to 13–15 years in boys.

3. Endurance develops later than everyone else. For example, if at 7 years old we take this indicator as 100%, then at 10 years old – 150%, at 14 – 15 years old – 400%. In general, by the age of 17–19, it reaches 85% of the endurance of an adult. The maximum level is reached between 25 and 30 years of age.

4. Development of motor coordination. It is caused not only by the maturation of the musculoskeletal system, but also depends on the conditions of upbringing.

Coordination of basic natural movements is formed before 3–5 years of age. The development of movements and mechanisms of their coordination occurs most intensively in the first years of life until adolescence. In adolescence, coordination of movements is somewhat impaired due to hormonal changes. However, this is a temporary phenomenon that disappears after 15 years. By the age of 18–25, it fully corresponds to the level of an adult (the so-called “golden period” of motor skills).

Blood .

Blood together with lymph And tissue fluid is internal environmentbody. This is liquid connective tissue. The volume of blood in the body is approximately 5 liters (from 5.2 liters in men to 3.9 liters in women).

Blood functions.

Human blood performs many important functions:

1. Transfer of organic substances from the small intestine to various organs and tissues, where they are used or stored in reserve. As well as the delivery of nutrients from places of storage to places of use.

2. Transport of waste from tissues to places of excretion.

3. Transport of hormones from the glands, where they are formed, to organs and tissues to transmit information.

4. Transfer of heat from deep-lying organs to organs that give off heat ( skin, intestines, lungs, bladder) – this prevents overheating.

All these are functions of plasma only. Shaped elements perform the following functions:

5. Delivery of oxygen from the lungs to all tissues and transfer of carbon dioxide in the opposite direction.

6. Protective: blood clotting, phagocytosis - capture and destruction of microbes, immune defense - antibodies.

7. Maintaining constant osmotic pressure and pH (plasma proteins are involved). Normal pH = 7.35 – 7.45.

Of great importance in maintaining the relative constancy of the composition and quantity of blood in the body is its “reservation” in special blood depots. This function is performed by several organs: spleen,liver, lungs, skin(subcutaneous layers), in which up to 50% of the blood is reserved.

Blood composition.

Consists of 2 parts : plasma And shaped elements.

Plasma – 55% (90% - water, 7% - proteins, 0.8% - fats, 0.1 - 0.12% glucose, 0.9% - salts.) pH = 7.3.

The plasma composition is maintained at the same level. Usually changes in composition lead to diseases.

a) Changes in glucose concentration (hyper- and hypoglycemia) cause fainting and death.

b) Changes in plasma pH (acidosis and alkalosis) accompany all major inflammatory processes: diabetes, poisoning, fasting, diseases of the gastrointestinal tract.

c) 0.9% NaCl solution is a physiological solution, at 0.3% it is hemolysis.

Formed elements – 45%, these are erythrocytes, leukocytes and platelets.

Shaped elements.

I . Erythrocytes (red blood cells)

Highly specialized, anucleate cells, shape - biconcave disk, diameter - 7-8 microns, 1 mm 3 = 4.5-6 million, total area = 3.5-3.8 thousand m 2. Life expectancy is 100-120 days, up to 15 million red blood cells are destroyed daily in the liver and spleen. New ones are formed in red bone marrow(hereinafter referred to as KKM), stock - in spleen. 90% of the red blood cell is made up of a hemoglobin molecule (iron + 4 protein molecules), which easily combines with gases and releases them easily.

Hemoglobin + 4 oxygen atoms = oxyhemoglobin(blood color is scarlet).

Hemoglobin + carbon dioxide atom = carboxyhemoglobin(blood color is dark cherry). Up to 80% of carbon dioxide is dissolved in the plasma and transferred. The combination of hemoglobin with carbon monoxide (CO) forms a very stable compound.

Used in diagnosing various diseases settling reactionerythrocytes (ROE). In a healthy person, the norm is 7-12 mm per hour (women), 3-9 mm per hour (men).

Anemia (anemia)– a decrease in the number of red blood cells in the blood or a decrease in hemoglobin. Causes: poor nutrition, infectious diseases, blood loss, vitamin deficiencies, cancer, iron deficiency.

II. Leukocytes (white blood cells).

Cells are of variable shape, have a nucleus, 6-8 thousand per mm 3. Based on their structure, they are divided into several groups (granular and non-granular), live from 1 day to several years, and are capable of independent movement. Formed in CMC, lymph nodes, spleen. Destroyed in liver And spleen, as well as in places of contact with microbes (nasal cavity, wounds).

Leukocyte function– protective ( phagocytosis), in certain cases this property causes undesirable consequences, for example, rejection during transplantations. By absorbing microbes, they die - pus (phagocytosis was discovered by I.I. Mechnikov in 1863). In addition, leukocytes provide immunity.

Immunity.

Immunity(" liberation, getting rid of something") is immunity to infectious diseases that occurs after an illness or vaccination. However, this concept is much broader.

According to McFarlane Burnet (one of the authors of the theory of immunity): “Immunity is the ability to recognize the invasion of foreign material into the body, to mobilize cells and the substances they produce to more quickly and effectively remove this material.”

Special leukocytes (lymphocytes) form substances - antibodies that participate in the neutralization of foreign substances.

Penetrates into the body antigen (foreign material). The T-lymphocyte (“helper”) recognizes it and transmits information about it to the B-lymphocyte, which synthesizes in large quantities antibodies (gamma globulins). Antibodies are specific, do not persist for a long time, but are quickly synthesized when necessary. An antibody + antigen reaction occurs, as a result of which a clot is formed (i.e., the antigen is no longer dangerous). These clots are removed by T lymphocytes (“killer cells”). Upon secondary exposure to the antigen, corresponding antibodies are instantly formed - immune memory. Vaccinations are based on this principle.

Types of immunity.

1. Congenital– inherited from parents (antibodies in the blood from birth).

2. Acquired– produced after microbes enter the bloodstream, after an illness.

3. Natural– congenital and acquired.

4. Artificial– appears after vaccination (introduction of weakened or killed pathogens into the body). The author of the method is L. Pasteur.

5. Serums– for quick help, the necessary antibodies are obtained from blood plasma, but immunity does not arise.

III. Platelets (blood platelets)

Colorless, nuclear-free, fragile cells, diameter 2-4 microns, 200-400 thousand per mm 3. Formed in KKM, are destroyed in spleen and wounds, live 8-11 days. They are easily destroyed when blood vessels are damaged or come into contact with air, starting a blood clotting reaction.

The mechanism of blood clotting.

Blood groups.

If during a blood transfusion the groups are not compatible, then the red blood cells stick together (agglutination) and death occurs.

There are 2 agglutinogens A and B in erythrocytes, and agglutinogens ά and β in plasma. Agglutination when the same name meets - A with ά, B with β.

Group 1 (0) – ά and β + 0, accepts your blood type, suits everyone.

Group 2 (A) – ά +A, accepts its group and 1, gives 4 to its group

Group 3 (B) – β +B, accepts its group and 1, gives 4 to its group.

Group 4 (AB) – 0 + AB, accepts everything, gives only to its group.

40% of people - group 1, 39% - group 2, 15% - group 3, 6% - group 4.

Rh factor, first discovered in rhesus monkeys, is a specific protein substance. It has been established that 86% of people have it (Rh factor is positive, designated as Rh+), and 14% do not have it (Rh factor is negative, Rh–).

Age-related characteristics of blood.

Changes are clearly expressed only in the first years of postnatal development. When comparing the blood of a newborn and an adult, the following picture is observed:

2. The number of red blood cells from 4.5 - 7.5 million in newborns to 4 - 5 million in adults.

3. ROE changes from 2-3 mm/h to 3-9 mm/h

4. The number of leukocytes changes from 10-30 thousand to 6-8 thousand.

5. The platelet count remains unchanged. Their number is the same in both newborns and adults.

Circulatory system .

Carries out the movement of blood, distributes it throughout the body and ensures that the blood performs its functions. Consists of the heart and blood vessels. The heart periodically contracts and pushes blood into the arteries, which, branching out, decrease to capillaries, capillaries merge to form veins. Veins flow into heart.Circulatory system–closed, blood flows only through vessels. Between the cells of the body and the blood there is an “intermediary” - tissue (intercellular) fluid.

Heart. (cor)

Located in the chest cavity, behind the breastbone. Most of it is to the left of the midline, with only the right atrium to the right. (Tilt approximately 40º). The weight of the heart is 300 g in men and 250 g in women, weight and size depend on body size and metabolic rate.

The heart is a hollow muscular organ, divided internally into four cavities: the right ventricle and atrium, left ventricle andatrium(maximum wall thickness in the left ventricle, minimum in the right atrium). The right and left sides of the heart are separated by a solid septum. The ventricles and atria are connected through leaflet valves (left - bicuspid, right - tricuspid), the valve leaflets are attached to the walls by tendon threads atria. When the atria contract, the valves open, then the ventricles contract, and the valves close (the tension of the tendon threads prevents them from opening). Heart consists of 3 layers: epicardium(outer layer) – myocardium(muscle layer) – endocardium(inner layer). In addition, the heart is surrounded by a connective tissue “bag” - pericardium(or pericardial sac).

Work of the heart.

Automaticity of the heart muscle– the ability of the heart to contract rhythmically under the influence of impulses arising in special cells in the right atrium (the center of automation). Excitation is transmitted to all muscle fibers. This ensures the independence of the heart from the nervous system (100 thousand times / day).

Cardiac cycle.

Carried out at 70-75 beats per minute.

A) Systole(contraction) of the atria – 0.1 sec.

b) Systole(contraction) of the ventricles – 0.3 sec.

V ) Diastole(relaxation of all chambers of the heart) – 0.4 sec.

Regulation of the heart: carried out by the nervous and humoral systems.

Parasympathetic nerves increase, sympathetic nerves decrease heart rate.

Adrenalin, calcium increases heart rate.

Both systems normally ensure the adaptation of cardiac activity to environmental conditions (exam, physical work, sleep).

Blood vessels .

I . Arteries:

a) They carry blood from the heart.

b) The middle layer of the wall is thick and consists of elastic and muscle fibers. Due to this, the arteries are elastic and flexible.

c) There are no semilunar valves.

d) Blood pressure is high and pulsating.

d) Blood flows quickly. (5 – 10 m/s).

f) The blood is oxygenated (i.e. enriched with oxygen, it is scarlet in color), with the exception of the pulmonary arteries.

II. Vienna:

a) They carry blood to the heart.

b) The middle layer is relatively thin and contains few muscle and elastic fibers.

c) Along its entire length there are semilunar valves that prevent the reverse flow of blood.

d) Blood pressure is low, not pulsating.

d) Blood flows slowly.

f) The blood is deoxygenated (i.e., containing carbon dioxide and depleted of oxygen, it is dark cherry in color), with the exception of the pulmonary veins.

III. Capillaries:

Connect arteries with veins. Serve as a site of exchange of substances between blood and tissues. (diameter = 5 -10 microns; 150 billion; 100 thousand km; per 1 mm 2 - from 100 to 2000 capillaries)

a) There is no middle layer, like arteries and veins. The walls consist of only one layer of epithelial cells.

b) There are no semilunar valves.

c) Blood pressure is decreasing, not pulsating.

d) Blood flow slows down.

e) Mixed; oxygenated and deoxygenated blood.

There are 2 veins per artery. Arteries are located relatively deep in the body (closed by muscles and bones), veins lie on the surface, just under the skin.

Circulation circles .

I . Small circle– from the right ventricle through the vessels of the lungs to the left atrium, blood passes through it in 4 seconds.

a) In the arteries there is venous blood.

b) At the border of the right ventricle and the pulmonary artery there are semilunar valves.

c) 2 pulmonary arteries enter the lungs, 4 pulmonary veins exit (with arterial blood).

d) Gas exchange occurs in the capillaries of the alveoli of the lungs - the blood is enriched with oxygen and releases carbon dioxide.

e) 4 pulmonary veins flow into the left atrium.

II. Big circle– from the left ventricle through the blood vessels of the whole body to the right atrium, blood passes through it in 23 seconds.

a) The left ventricle (the myocardium is 3 times thicker) ejects blood into the aorta (the largest human artery), and at the border between the ventricle and the aorta there are semilunar valves.

b) Arteries branch from the aorta, branching into many capillaries in the organs.

c) In the capillaries there is an exchange with tissue fluid.

d) Blood collects in the upper (from the head) and lower (from the torso) hollow veins.

d) The vena cava drains into right atrium.

Movement of blood through vessels.

Blood pressure (BP) – when the ventricles contract, pressure is created in the vessels (max – aorta, min – vena cava). 120 mmHg Art. – ventricular systole, 70 mm Hg. Art. – diastole. High blood pressure - hypertension, low pressure - hypotension.

Pulse- rhythmic oscillations of the walls of blood vessels that occur during the hydrodynamic impact of a wave of blood on the walls of the arteries during cardiac ejection. The normal pulse rate is 60-80 beats per minute. 70 – 72 beats for men, 78 – 82 for women. Minimum – 28, maximum – 200 strokes. Pulse rate is not related to blood speed and heart rate, but depends on the elasticity of the artery walls.

Blood speed:

a) The blood circulation is equal to: 23 seconds in a large circle and 4 seconds in a small circle, therefore, a complete circulation takes place in 27 seconds.

b) In the aorta, the maximum speed is 0.5 m/s (up to 5 l/min.)

c) The minimum velocity in the capillaries is 0.5 - 1.2 mm/sec, because the total lumen of the capillaries is 500 times greater than the lumen of the arteries.

d) In the veins – 0.25 m/sec.

The movement of blood in the veins is carried out due to:

a) Operation of the semilunar valves.

b) Contractions of skeletal muscles.

c) The suction action of the chest as it expands.

Redistribution of blood.

Depending on the organ’s need for oxygen and nutrients, the blood supply changes due to contraction or relaxation of the muscles of the vessel walls. This is regulated by the autonomic nervous system; hormones - adrenaline, acetylcholine.

The control center for the operation of the circulatory system is located in medulla oblongata.

Lymph circulation.

As blood passes through the network of capillaries, part of the plasma is filtered through the walls of the capillaries into the smallest spaces, forming between the cells - tissue fluid(20 l). It is with its help that the exchange of substances between blood and tissues occurs. Naturally, the blood cannot constantly lose so much fluid, and a significant part of it returns to the bloodstream. Some returns directly back to the capillaries, while the other goes through the lymph circulation system.

All tissues have blind ending lymphatic capillaries.

Tissue fluid is pumped into them, turning into lymph(3 l/day).

Lymph moves in the vessels (their structure is similar to veins) due to the semilunar valves, the pressure of tissue fluid, muscle contraction, and the suction effect of tissue fluid.

Lymphatic vessels merge to form lymph nodes. 460 knots, diameter 2 – 30 mm. Lymphocytes accumulate in them, microorganisms are retained here (the lymph nodes swell).

Congestion of lymph nodes: in the armpit; in the popliteal and elbow bends; in the chest and abdominal cavity; in the groin area; on the neck; in the mucous membrane of the pharynx – tonsils.

From the lymph nodes, lymph moves through the vessels to right(collects lymph from the right chest and arm) and left(from the rest of the body) infantlymphatic ducts, which flow into inferior vena cava.

Bone connections(Fig. No. 49) combine the bones of the skeleton into a single whole, hold them next to each other and provide them with greater or lesser mobility, spring function, as well as growth of the skeleton and the human body as a whole.

There are 3 types of bone connections (Fig. No. 24):

- continuous(synarthrosis) – ligaments, membranes, sutures (skull bones), impaction (dental-alveolar joints), cartilaginous synchondrosis(temporary, permanent), bone - synostosis;

- intermittent(joints, diarthrosis);

- transitional form(half-joints, symphyses, hemiarthrosis).

Continuous connections between bones using dense fibrous connective tissue are syndesmoses, with the help of cartilage - synchondrosis, with the help of bone tissue - synostoses. The most advanced types of bone connections in the human body are discontinuous connections - joints (diarthrosis). These are movable connections of bones with each other, in which the function of movement comes to the fore. There are many joints in the human body. There are about 120 of them in one spinal column. But the structure of all joints is the same.

The joint is divided into main and auxiliary elements.

The main elements of the joint include:

1) articular surfaces;

2) articular cartilage;

3) joint capsule;

4) articular cavity;

5) synovial fluid.

Accessory elements of the joint include:

1) ligaments;

2) articular discs;

3) articular menisci;

4) articular lips;

5) synovial bursae.

Articular surfaces- these are the areas of contact of articulating bones. They have different shapes: spherical, cup-shaped, ellipsoidal, saddle-shaped, condylar, cylindrical, block-shaped, helical. If the articulating surfaces of bones correspond to each other in size and shape, then these are congruent (lat. congruens - corresponding, coinciding) articular surfaces. If the articular surfaces do not correspond to each other in shape and size, then these are incongruent articular surfaces. Articular cartilage, 0.2 to 6 mm thick, covers the articular surfaces and thus smoothes out bone irregularities and cushions movement. Most articular surfaces are covered with hyaline cartilage. The joint capsule hermetically seals the articular surfaces from the environment. It consists of two layers: the outer one - a fibrous membrane, very dense and strong, and the inner one - the synovial membrane, which produces fluid - synovium. Articular cavity- this is a narrow gap limited by the articular surfaces and the synovial membrane, hermetically isolated from the surrounding tissues. Always has negative pressure. Synovial fluid- This is a viscous transparent liquid, reminiscent of egg white, which is located in the joint cavity. It is a product of the exchange of the synovial membrane of the capsule and articular cartilage. Acts as a lubricant and buffer cushion.

Ligaments- extra-articular (extra-capsular and capsular) and intra-articular - strengthen the joint and capsule. Articular discs and menisci- these are solid and non-continuous cartilaginous plates that are located between articular surfaces that do not fully correspond to each other (incongruent). They smooth out the unevenness of the articulating surfaces and make them congruent. Articular labrum- a cartilage cushion around the articular cavity to increase its size (shoulder, hip joints). Synovial bursa- this is a protrusion of the synovial membrane in thinned areas of the fibrous membrane of the joint capsule (knee joint).

Joints differ from each other in structure, shape of articulating surfaces, range of motion (biomechanics). A joint formed by only two articular surfaces is simple joint; three or more articular surfaces, - complex joint. A joint characterized by the presence of an articular disc (meniscus) between the articulating surfaces, which divides the joint cavity into two floors, is complex joint. Two anatomically isolated joints acting together constitute combined joint.

Hemiarthrosis (half-joint, symphysis)- This is a cartilaginous connection of bones, in which there is a narrow gap in the center of the cartilage. Such a connection is not covered with a capsule on the outside, and the inner surface of the gap is not lined with synovial membrane. In these joints, slight displacements of the bones relative to each other are possible. These include the symphysis of the manubrium of the sternum, the intervertebral symphysis and the pubic symphysis.

3. Spinal column(Fig. No. 25 and 26)

The spinal column, thorax and skull are classified as axial skeleton, the bones of the upper and lower extremities are called accessory skeleton.

Spinal column(Fig. No. 27), or the spine, is located on the back side of the body. It performs the following functions:

1) supporting, being a rigid rod that holds the weight of the body;

2) protective, forming a cavity for the spinal cord, as well as the organs of the thoracic, abdominal and pelvic cavities;

3) locomotor, participating in the movements of the torso and head;

4) spring, or springy, softening the shocks and shocks received by the body when jumping, running, etc.

The spinal column contains 33-34 vertebrae, of which 24 are free - true (cervical, thoracic, lumbar), and the rest are fused - false (sacral, coccygeal). There are 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4-5 coccygeal vertebrae. True vertebrae have a number of common features. In each of them, a thickened part is distinguished - the body facing forward, and an arc extending from the body backward, limiting the vertebral foramen. When the vertebrae connect, these openings form the spinal canal, which houses the spinal cord. 7 processes extend from the arch: one is unpaired - the spinous one is directed backward; the rest are paired: the transverse processes are directed to the sides of the vertebrae, the upper articular processes go up and the lower articular processes go down. At the junction of the vertebral arch with the body, on each side there are two vertebral notches: superior and inferior, which, when connecting the vertebrae, form intervertebral foramina. Spinal nerves and blood vessels pass through these openings.

Cervical vertebrae(Fig. No. 28) have characteristic features that distinguish them from the vertebrae of other sections. The main difference is the presence of an opening in the transverse processes and bifurcation at the end of the spinous processes. The spinous process of the VII cervical vertebra is not split, it is longer than the others and can be easily felt under the skin (protruding vertebra). On the anterior surface of the transverse processes of the VI cervical vertebra there is a well-developed carotid tubercle - a place where the common carotid artery can easily be compressed to temporarily stop bleeding. I cervical vertebra - atlas has no body and spinous process, but contains only two arches and lateral masses on which the articular fossae are located: the upper ones for articulation with the occipital bone, the lower ones for articulation with the II cervical vertebra. II cervical vertebra - axial(epistropheus) - has an odontoid process on the upper surface of the body - a tooth around which the head rotates (together with the atlas).

U thoracic vertebrae(Fig. No. 29) the spinous processes are the longest and are directed downward, in the lumbar ones they are wide in the form of quadrangular plates and directed straight back. On the body and transverse processes of the thoracic vertebrae there are costal fossae for articulation with the heads and tubercles of the ribs.

Sacrum bone, or sacrum, consists of five sacral vertebrae (Fig. No. 30 and 31), which by the age of 20 grow together into one monolithic bone, which gives this part of the spine the necessary strength.

Coccygeal bone, or coccyx, consists of 4-5 small underdeveloped vertebrae.

The human spinal column has several bends. Curves that are convex forward are called lordoses, convex backwards are called kyphosis, and curves that are convex to the right or left are called scoliosis. The following physiological curves are distinguished: cervical and lumbar lordosis, thoracic and sacral kyphosis, thoracic (aortic) scoliosis. The latter occurs in 1/3 of cases, is located at the level of the III-V thoracic vertebrae in the form of a small convexity to the right and is caused by the passage of the thoracic aorta at this level.

Rib cage

Rib cage(Fig. No. 32), is formed by 12 pairs of ribs, the sternum and the thoracic spine. It is the skeleton of the walls of the chest cavity, which contains important internal organs (heart, lungs, trachea, esophagus, etc.).

Sternum, the sternum, is a flat bone consisting of three parts: the upper - the manubrium, the middle - the body and the lower - the xiphoid process. In newborns, all 3 parts of the sternum are built of cartilage, which contains ossification nuclei. In adults, only the handle and body are connected to each other using cartilage. By the age of 30-40, the ossification of cartilage is completed, and the sternum becomes a monolithic bone. On the upper edge of the manubrium there is a jugular notch, and on the sides of it there are clavicular notches. There are seven notches for ribs on the outer edges of the body and handle.

Ribs- These are long, flat bones. There are 12 pairs of them. Each rib has a large posterior bony part and a smaller anterior cartilaginous part, which are fused together. A rib has a head, a neck and a body. Between the neck and body of the upper 10 pairs there is a tubercle of the rib, which has an articular surface for articulation with the transverse process of the vertebra. On the head of the rib there are two articular platforms for articulation with the costal fossae of two adjacent vertebrae. The rib has outer and inner surfaces, upper and lower edges. On the inner surface along the lower edge, a rib groove is visible - a trace of the location of blood vessels and nerves.

The ribs are divided into three groups. The upper 7 pairs of ribs, reaching the sternum with their cartilages, are called true. The next 3 pairs, connected to each other by their cartilages and forming the costal arch, are called false. The last 2 pairs lie freely in soft tissues with their ends, they are called hesitant ribs.

The chest as a whole is shaped like a truncated cone. The upper opening of the chest, limited by the body of the first thoracic vertebra, the first pair of ribs and the upper edge of the manubrium of the sternum, is free. The apexes of the lungs protrude through it into the neck area, as well as the trachea, esophagus, blood vessels and nerves. The lower opening of the chest is limited by the body of the XII thoracic vertebra, the ribs of the XI and XII pairs, the costal arches and the xiphoid process. This hole is hermetically sealed with a diaphragm. Since the first rib moves very little during breathing, therefore ventilation of the apices of the lungs during breathing is minimal. This creates favorable conditions for the development of inflammatory processes in the apexes of the lungs.

Numerous present in the human body bone connections It is advisable to present it in the form of a classification. In accordance with this classification, there are two main types of bone connections - continuous and discontinuous, each of which in turn is divided into several groups (Gayvoronsky I.V., Nichiporuk G.I., 2005).

Types of bone joints

Continuous connections (synarthrosis, synarthrosis)

Discontinuous joints (diarthrosis, diarthrosis; synovial joints or joints, articulationes synoviales)

I. Fibrous compounds (articulationes librosae): ligaments (ligamenta); membranes (membranae); fontanelles (fonticuli); sutures (suturae); gomphosis

II. Cartilaginous connections (articulationes cartilagineae): connections using hyaline cartilage (temporary); connections with fibrocartilage (permanent)

III. Connections with bone tissue (synostosis)

According to the axes of rotation and the shape of the articular surfaces:

By the number of articular surfaces: simple (art. simplex); complex (art. composite)

According to one-stage joint function: combined (art. combinatoria)

It should be noted that the relief of bones often reflects the specific type of joint. Continuous joints on bones are characterized by tuberosities, ridges, lines, pits and roughness, while discontinuous joints are characterized by smooth articular surfaces of various shapes.

Continuous bone connections

There are three groups of continuous bone connections: fibrous, cartilaginous and osseous.

I. Fibrous joints of bones, or connections using connective tissue - syndesmoses. These include ligaments, membranes, fontanels, sutures and impactions.

Ligaments are connections made by connective tissue that look like bundles of collagen and elastic fibers. By their structure, ligaments with a predominance of collagen fibers are called fibrous, and ligaments containing predominantly elastic fibers are called elastic. Unlike fibrous ligaments, elastic ligaments are able to shorten and return to their original shape after the load is removed.

According to the length of the fibers, ligaments can be long (posterior and anterior longitudinal ligaments of the spinal column, supraspinous ligament), connecting several bones over a long distance, and short, connecting adjacent bones (interspinous, intertransverse ligaments and most ligaments of the bones of the extremities).

In relation to the joint capsule, intra-articular and extra-articular ligaments are distinguished. The latter are considered as extracapsular and capsular. Ligaments, as an independent type of bone connection, can perform various functions:

retaining or fixing (sacrotuberous ligament, sacrospinous, interspinous, intertransverse ligaments, etc.);
the role of the soft skeleton, as they are the place of origin and attachment of muscles (most ligaments of the limbs, ligaments of the spinal column, etc.);
formative, when they, together with the bones, form vaults or openings for the passage of blood vessels and nerves (superior transverse ligament of the scapula, pelvic ligaments, etc.).

Membranes are connections made by connective tissue that look like interosseous membranes that, unlike ligaments, fill large spaces between bones. The connective tissue fibers in the membranes, mainly collagen, are located in a direction that does not interfere with movement. Their role is in many ways similar to ligaments. They also hold bones relative to each other (intercostal membranes, interosseous membranes of the forearm and lower leg), serve as the origin of muscles (the same membranes) and form openings for the passage of blood vessels and nerves (obturator membrane).

Fontanas are connective tissue formations with a large amount of intermediate substance and sparsely located collagen fibers. Fontana create conditions for displacement of the skull bones during childbirth and promote intensive bone growth after birth. The anterior fontanel reaches the largest size (30 x 25 mm). It closes in the second year of life. The posterior fontanel measures 10 x 10 mm and completely disappears by the end of the second month after birth. Paired wedge-shaped and mastoid fontanelles are even smaller. They heal before birth or in the first two weeks after birth. The fontanelles are eliminated due to the proliferation of the skull bones and the formation of suture connective tissue between them.

Sutures are thin layers of connective tissue located between the bones of the skull, containing a large number of collagen fibers. The shape of the sutures is jagged, scaly and flat; they serve as a growth zone for the bones of the skull and have a shock-absorbing effect during movements, protecting the brain, organs of vision, hearing and balance from damage.

Impactions are connections of teeth with the cells of the alveolar processes of the jaws using dense connective tissue, which has a special name - periodontium. Although this is a very strong connection, it also has pronounced shock-absorbing properties when the tooth is loaded. The thickness of the periodontium is 0.14–0.28 mm. It consists of collagen and elastic fibers oriented along the entire length perpendicularly from the walls of the alveoli to the root of the tooth. Between the fibers lies loose connective tissue containing a large number of vessels and nerve fibers. When the jaws are strongly clenched due to the pressure of the antagonist tooth, the periodontium is strongly compressed, and the tooth is immersed in the cell up to 0.2 mm.

With age, the number of elastic fibers decreases, and when stressed, the periodontium is damaged, its blood supply and innervation are disrupted, teeth become loose and fall out.

II. Cartilaginous joints of bones- synchondrosis. These compounds are represented by hyaline or fibrous cartilage. Comparing these cartilages with each other, it can be noted that hyaline cartilage is more elastic, but less durable. With the help of hyaline cartilage, the metaphyses and epiphyses of the tubular bones and individual parts of the pelvic bone are connected. Fibrous cartilage mainly consists of collagen fibers, therefore it is more durable and less elastic. This cartilage connects the vertebral bodies. The strength of cartilage joints also increases due to the fact that the periosteum from one bone passes to another without interruption. In the area of cartilage, it turns into perichondrium, which in turn firmly fuses with cartilage and is supported by ligaments.

According to the duration of their existence, synchondrosis can be permanent or temporary, that is, existing until a certain age, and then replaced by bone tissue. Under normal physiological conditions, metaepiphyseal cartilages, cartilages between individual parts of flat bones, and cartilage between the main part of the occipital and the body of the sphenoid bones are temporary. These compounds are mainly represented by hyaline cartilage. The cartilages that form the intervertebral discs are called permanent; cartilage located between the bones of the base of the skull (sphenoid-petrosal and sphenoid-occipital), and cartilage between the first rib and sternum. These compounds are mainly represented by fibrous cartilage.

The main purpose of synchondrosis is to soften shocks and stresses under heavy loads on the bone (shock absorption) and ensure a strong connection between the bones. Cartilage joints at the same time have great mobility. The range of movements depends on the thickness of the cartilage layer: the thicker it is, the greater the range of movements. As an example, we can cite various movements in the spinal column: bending forward, backward, to the sides, twisting, springing movements, which are especially developed in gymnasts, acrobats and swimmers.

III. Connections using bone tissue- synostosis. These are the strongest connections from the group of continuous ones, but have completely lost their elasticity and shock-absorbing properties. Under normal conditions, temporary synchondroses undergo synostosis. In some diseases (bechterew's disease, osteochondrosis, etc.), ossification can occur not only in all synchondroses, but also in all syndesmoses.

Discontinuous bone connections

Discontinuous joints are joints or synovial joints. A joint is a discontinuous cavity joint formed by articulating articular surfaces covered with cartilage, enclosed in an articular capsule (capsule), which contains synovial fluid.

The joint must necessarily include three main elements: the articular surface covered with cartilage; joint capsule; joint cavity.

1. Articular surfaces- These are areas of bone covered with articular cartilage. In long tubular bones they are located on the epiphyses, in short ones - on the heads and bases, in flat bones - on the processes and body. The shapes of the articular surfaces are strictly determined: more often there is a head on one bone, a fossa on the other, less often they are flat. The articular surfaces on the articulating bones must correspond in shape to each other, that is, be congruent. More often, the articular surfaces are lined with hyaline (vitreous) cartilage. Fibrous cartilage covers, for example, the articular surfaces of the temporomandibular joint. The thickness of the cartilage on the articular surfaces is 0.2-0.5 cm, and in the articular fossa it is thicker at the edge, and on the articular head - in the center.

In the deep layers, the cartilage is calcified and firmly connected to the bone. This layer is called mistleted, or impregnated with calcium carbonate. Chondrocytes (cartilage cells) in this layer are surrounded by connective tissue fibers located perpendicular to the surface, i.e., in rows or columns. They are adapted to resist pressure forces on the articular surface. In the superficial layers, connective tissue fibers predominate in the form of arcs, starting and ending in the deep layers of cartilage. These fibers are oriented parallel to the surface of the cartilage. In addition, this layer contains a large amount of intermediate substance, so the surface of the cartilage is smooth, as if polished. The surface layer of cartilage is adapted to resist frictional forces (tangential forces). With age, cartilage undergoes desalination, its thickness decreases, and it becomes less smooth.

The role of articular cartilage is that it smoothes out the unevenness and roughness of the articular surface of the bone, giving it greater congruence. Due to its elasticity, it softens shocks and shocks, so in joints that bear a large load, the articular cartilage is thicker.

2. Joint capsule- this is a hermetic capsule surrounding the articular cavity, growing along the edge of the articular surfaces or at a slight distance from them. It consists of an outer (fibrous) membrane and an inner (synovial) membrane. The fibrous membrane, in turn, consists of two layers of dense connective tissue (outer longitudinal and inner circular), in which blood vessels are located. It is strengthened by extra-articular ligaments, which form local thickenings and are located in areas of greatest load. The ligaments are usually closely connected to the capsule, and they can only be separated artificially. Rarely there are ligaments isolated from the joint capsule, for example, the lateral tibiofibular and fibular. In sedentary joints, the fibrous membrane is thickened. In moving joints it is thin, weakly stretched, and in some places it is so thin that the synovial membrane even protrudes outward. This is how synovial inversions (synovial bursae) are formed, usually located under the tendons.

The synovial membrane faces the joint cavity, is abundantly supplied with blood, and is lined from the inside with synoviocytes capable of secreting synovial fluid. The synovial membrane covers the entire joint cavity from the inside, extends to the bones and intra-articular ligaments. Only the surfaces represented by cartilage remain free from it. The synovial membrane is smooth, shiny, and can form numerous processes - villi. Sometimes these villi break off and become foreign bodies on the interarticular surfaces, causing short-term pain and preventing movement. This condition is called "joint mouse". The synovial membrane can lie directly on the fibrous membrane or be separated from it by a subsynovial layer or a fatty layer, therefore fibrous, areolar and fatty synovial membranes are distinguished.

Synovial fluid in its composition and nature of formation is a transudate - an effusion of blood plasma and lymph from the capillaries adjacent to the synovial membrane. In the joint cavity, this fluid is mixed with detritus of rejected synoviocyte cells and abraded cartilage. In addition, synovial fluid contains mucin, mucopolysaccharides and hyaluronic acid, which give it viscosity. The amount of fluid depends on the size of the joint and ranges from 5 mm3 to 5 cm3. Synovial fluid performs the following functions:

lubricates articular surfaces (reduces friction during movements, increases gliding);
connects articular surfaces, holds them relative to each other;
softens the load;
nourishes articular cartilage;
participates in metabolism.

3. Joint cavity- this is a hermetically sealed space, limited by the articular surfaces and capsule, filled with synovial fluid. It is possible to distinguish a joint cavity on an intact joint only conditionally, since there is no void between the articular surfaces and the capsule; it is filled with synovial fluid. The shape and volume of the cavity depend on the shape of the articular surfaces and the structure of the capsule. In low-moving joints it is small, in highly mobile ones it is large and can have eversion, spreading between bones, muscles and tendons. There is negative pressure in the joint cavity. When the capsule is damaged, air enters the cavity and the articular surfaces diverge.

In addition to the main elements, joints may contain auxiliary elements that ensure optimal joint function. These are intra-articular ligaments and cartilages, articular lips, synovial folds, sesamoid bones and synovial bursae.

Movements in the joints can only occur around three axes of rotation:

frontal (axis corresponding to the frontal plane dividing the body into anterior and posterior surfaces);
sagittal (axis corresponding to the sagittal plane dividing the body into right and left halves);
vertical, or its own axis.

For the upper limb, the vertical axis passes through the center of the head of the humerus, the head of the humeral condyle, the head of the radius and the ulna. For the lower limb - in a straight line connecting the anterior superior iliac spine, the inner edge of the patella and the thumb.

The articular surface of one of the articulating bones, which has the shape of a head, can be presented in the form of a ball, ellipse, saddle, cylinder or block. Each of these surfaces corresponds to an articular fossa. It should be noted that the articular surface can be formed by several bones, which together give it a certain shape (for example, the articular surface formed by the bones of the proximal row of the wrist).

1 - ellipsoidal; 2 - saddle-shaped; 3 - spherical; 4 - block-shaped; 5 - flat

Movements in the joints around the axes of rotation are determined by the geometric shape of the articular surface. For example, the cylinder and block rotate only about one axis; ellipse, oval, saddle - around two axes; a ball or flat surface - around three.

The number and possible types of movements around existing rotation axes are presented in the tables. Thus, two types of movements are noted around the frontal axis (flexion and extension); there are also two types of movements around the sagittal axis (adduction and abduction); when moving from one axis to another, another movement occurs (circular or conical); around the vertical axis there is one movement (rotation), but it can have subtypes: inward or outward rotation (pronation or supination).

Axes of rotation, number and types of possible movements

The maximum number of possible types of movements in the joints, depending on the number of axes of rotation and the shape of the articular surface

Joint alignment	Shape of the articular surface	Implemented rotation axes	Number of movements	Types of movements
Uniaxial	Block-shaped	Frontal	2	Flexion, extension
Uniaxial	Rotary (cylindrical)	Vertical	1	Rotation
Biaxial	Elliptical, saddle-shaped	Sagittal and frontal	5	Flexion, extension, adduction, abduction, circular motion
Biaxial	Condylar	Frontal and vertical	3	Flexion, extension, rotation
Multi-axis	spherical, flat	Frontal, sagittal and vertical	6	Flexion, extension, adduction, abduction, circular motion, rotation

Thus, there are only 6 types of movements. Additional movements are also possible, such as sliding, springing (removing and bringing together articular surfaces during compression and stretching) and twisting. These movements do not relate to individual joints, but to a group of combined ones, for example intervertebral ones.

Based on the classification of joints, it is necessary to characterize each individual group.

I. Classification of joints according to axes of rotation and shape of articular surfaces:

Uniaxial joints- these are joints in which movements are made only around one axis. In practice, such an axis is either frontal or vertical. If the axis is frontal, then movements in these joints are performed in the form of flexion and extension. If the axis is vertical, then only one movement is possible - rotation. Representatives of uniaxial joints according to the shape of the articular surfaces are: cylindrical (articulatio trochoidea) (rotational) and block-shaped (ginglymus). Cylindrical joints carry out movements around a vertical axis, that is, they rotate. Examples of such joints are: the median atlantoaxial joint, the proximal and distal radioulnar joints.

The trochlear joint is similar to a cylindrical joint, only it is located not vertically, but horizontally and has a ridge on the articular head, and a notch on the articular fossa. Due to the scallop and notch, sideways displacement of the articular surfaces is impossible. The capsule of such joints is free in front and behind and is always strengthened by lateral ligaments that do not interfere with movements. Block joints always work around the frontal axis. An example is the interphalangeal joints.

A type of trochlear joint is the cochlear joint (articulatio cochlearis), or screw-shaped joint, in which the notch and ridge are beveled and have a helical motion. An example of a cochlear joint is the ulnohumeral joint, which also operates around the frontal axis. Thus, uniaxial joints have one or two types of movement.

Biaxial joints- joints that work around two of the three available axes of rotation. So, if movements are performed around the frontal and sagittal axes, then such joints realize 5 types of movements: flexion, extension, adduction, abduction and circular movement. According to the shape of the articular surfaces, these joints are ellipsoidal or saddle-shaped (articulatio ellipsoidea, articulatio sellaris). Examples of ellipsoidal joints: atlanto-occipital and radiocarpal; saddle: carpometacarpal joint of the 1st finger.

If movements are carried out around the frontal and vertical axes, then only three types of movements can be realized - flexion, extension and rotation. In shape these are condylar joints (articulatio bicondyllaris), for example the knee and temporomandibular joints.

Condylar joints are a transitional form between uniaxial and biaxial joints. The main axis of rotation in them is the frontal one. Unlike uniaxial joints, they have a larger difference in the areas of the articular surfaces, and therefore the range of movements increases.

Multi-axis joints- these are joints in which movements are carried out around all three axes of rotation. They make the maximum possible number of movements - 6 types. These are spherical joints (articulatio spheroidea), for example the shoulder. A type of spherical joint is cup-shaped (articulatio cotylica), or nut-shaped (articulatio enarthrosis), for example, the hip. It is characterized by a deep articular fossa, a strong capsule reinforced by ligaments, and a lesser range of motion. If the surface of a ball has a very large radius of curvature, then it approaches a flat surface. A joint with such a surface is called flat (articulatio plana). Flat joints are characterized by a small difference in the areas of the articular surfaces, strong ligaments, and movements in them are sharply limited or absent altogether (for example, in the sacroiliac joint). In this regard, these joints are called sedentary (amphiarthrosis).

II. Classification of joints by the number of articular surfaces.

Simple joint (articulatio simplex)- a joint that has only two articular surfaces, each of which can be formed by one or more bones. For example, the articular surfaces of the interphalangeal joints are formed by only two bones, and one of the articular surfaces in the wrist joint is formed by three bones of the proximal row of the wrist.

Compound joint is a joint in one capsule of which there are several articular surfaces, therefore, several simple joints that can function both together and separately. An example of a complex joint is the elbow joint, which has 6 separate articular surfaces that form 3 simple joints: brachioradial, humeroulnar, proximal radioulnar. Some authors also include the knee joint as a complex joint. Considering the articular surfaces on the meniscus and patella, they distinguish such simple joints as the femoral-meniscal, meniscal-tibial and femoral-patellar. We consider the knee joint to be simple, since the menisci and patella are auxiliary elements.

III. Classification of joints according to simultaneous joint function.

Combined joints (articulatio combinatoria)- these are joints that are anatomically separated, that is, located in different articular capsules, but functioning only together. For example, the temporomandibular joint, proximal and distal radioulnar joints. It should be emphasized that in true combined joints it is impossible to make a movement in only one of them, for example, only in one temporomandibular joint. When combining joints with different shapes of articular surfaces, movements are realized along a joint that has a smaller number of axes of rotation.

Factors that determine the range of motion in joints.

There are several methods for determining the range of motion in joints. Traumatologists determine it using a protractor. Each joint has its own initial positions. The starting position for the shoulder joint is the position of the arm hanging freely along the body. For the elbow joint - full extension (180°). Pronation and supination are determined with the elbow joint bent at a right angle and the hand positioned in the sagittal plane.

In anatomical studies, the magnitude of the angle of mobility can be calculated from the difference in the arcs of rotation on each of the articulating articular surfaces. The magnitude of the angle of mobility depends on a number of factors: gender, age, degree of training, individual characteristics.

Joint diseases
IN AND. Mazurov