Bone connections. Types of bones

All the bones of the human body are connected to each other. These compounds differ in their structure and degree of mobility and therefore have different names (see diagram).

All types of bone joints are usually divided into two main groups: 1) continuous joints, i.e., joints that do not have a cavity, and 2) discontinuous joints, or joints in which there is a cavity. In continuous connections, there is little or no movement, discontinuous connections are mobile.

The main types of continuous connections are syndesmosis and synchondrosis (Fig. 16).

Syndesmoses are called connections of bones with the help of fibrous connective tissue. They will lean towards them bundles(for example, ligaments between the spinous processes of the vertebrae) and membranes, or membranes (for example, the interosseous membrane between the two bones of the forearm). A variety of syndesmosis are sutures - connections of the bones of the skull through thin layers of fibrous connective tissue.

Synchondroses are called connections of bones with the help of cartilage tissue. An example of synchondrosis is the connection of the vertebral bodies through intervertebral cartilage (discs). In some parts of the skeleton, during development, the cartilage between the bones is replaced by bone tissue. As a result, bone fusions are formed - synostoses. An example of synostosis is the fusion of the sacral vertebrae.

joints(articulatio) - the most common type of connection of bones in the human body. Each joint must have three main elements: articular surfaces, joint bag And articular cavity(see fig. 16).

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

The articular bag (capsule) is stretched between the articulating bones, attached along the edges of the articular surfaces and passes into the periosteum. Two layers are distinguished in the articular bag: the outer one is fibrous and the inner one is synovial. The joint capsule in some joints has protrusions - synovial bags (bursae). Synovial bags are located between the joints and tendons of the muscles located in the circumference of the joint, and reduce the friction of the tendon on the joint capsule. The articular bag on the outside in most joints is reinforced with ligaments. The articular cavity has a slit-like shape, is limited by the articular cartilage and the articular bag and is hermetically closed. The joint cavity contains a small amount of viscous fluid - synovia, which is secreted by the synovial layer of the articular bag. Synovia lubricates the articular cartilage, thereby reducing friction in the joints during movement. The articular cartilages of the articulating bones are tightly adjacent to each other, which is facilitated by negative pressure in the joint cavity. In some joints there are auxiliary formations: intra-articular ligaments And intra-articular cartilage(discs and menisci).

There is a relationship between the nature of movements in the joints and the shape of the articular surfaces. Articular surfaces are compared with segments of geometric shapes. According to the shape of the articular surfaces, the joints are divided into spherical, ellipsoid, saddle, cylindrical And blocky(Fig. 17). When determining movements in the joints, three main axes are mentally drawn: transverse, anteroposterior, or sagittal, and vertical. There are the following basic movements: around the transverse axis - bending(flexion) and extension(extension); around the sagittal axis - abduction(abduction) and cast(adduction); around the vertical axis - rotation(rotation). In some joints, peripheral, or circular, movement is also possible, when the free end of the bone describes a circle. In some joints, movements around one axis are possible, in others - around two axes, in others - around three axes. Uniaxial joints are cylindrical and block-shaped, biaxial - ellipsoid and saddle-shaped, triaxial or multiaxial - spherical. An example of a uniaxial joint is the interphalangeal joints of the fingers, a biaxial joint is the wrist joint, and a triaxial joint is the shoulder joint. In addition, there are joints with smooth articular surfaces. Such joints are called flat; only slight slip is possible in them. The joint is called simple, if it is formed by two bones, and difficult, if three or more bones are connected in it. Two or more joints, in which movements can occur only simultaneously, together make up the so-called combined joint.

The bones of the human skeleton are combined into a common functional system (the passive part of the musculoskeletal system) using various types of connections. All bone joints are divided into three types: continuous, discontinuous and symphyses. Depending on the type of tissues that connect the bones, the following types of continuous connections are distinguished: fibrous, bone and synchondrosis (cartilaginous connections) (Fig. 9).

Rice. 9. Types of bones connection (diagram):

A - joint; B - fibrous connection; IN - synchondrosis (cartilaginous connection); G- symphysis (hemiarthrosis); 1 - periosteum; 2- bone; 3- fibrous connective tissue; 4 - cartilage; 5 - synovial membrane; 6 - fibrous membrane; 7 - articular cartilage; 8 - articular cavity; 9 - a gap in the interpubic disc; 10- interpubic disc

Fibrous connections have high strength and low mobility. These include syndesmoses (ligaments and interosseous membranes), sutures, and impaction.

Ligaments are thick bundles or plates formed by dense fibrous connective tissue with a large number of collagen fibers. In most cases, ligaments connect two bones and reinforce the joints, limiting their movement, and withstand significant loads.

Interosseous membranes connect the diaphysis of tubular bones, serve as a place of attachment of muscles. There are openings in the interosseous membranes through which blood vessels and nerves pass.

A variety of fibrous compounds are skull sutures, which, depending on the configuration of the connected edges of the bone, are spongy, scaly and flat. In all types of sutures between the connected bones there are thin layers of connective tissue.

Injection - a special type of fibrous connection, which is observed in the connection of the tooth with the bone tissue of the dental alveolus. Between the tooth and the bone wall there is a thin plate of connective tissue - paradont.

Synchondrosis - connecting bones with cartilage. They are characterized by elasticity, strength; they perform a cushioning function.

The replacement of cartilage between bones by bone tissue is called synostosis. Mobility in such compounds disappears, and strength increases.

Discontinuous (synovial or articular) joints are the most mobile joints of bones. They have great mobility and a variety of movements. Characteristic features of the joint are the presence of articular surfaces, articular cavity, synovial fluid and capsule. The articular surfaces of the bones are covered with hyaline cartilage with a thickness of 0.25 to 6 mm, depending on the load on the joint. The articular cavity is a slit-like space between the articular surfaces of the bones, which is surrounded on all sides by the articular capsule and contains a large amount of synovial fluid.

The joint capsule covers the connecting ends of the bones, forms a sealed bag, the walls of which have two layers: the outer one is fibrous and the inner one is the synovial membrane.

Outer fibrous layer consists of a dense fibrous connective tissue with a longitudinal direction of the fibers and provides the articular capsule with significant strength. In some joints, the fibrous layer can form thickenings (capsular ligaments) that strengthen the articular bag.

Inner layer (synovium) has small outgrowths (villi rich in blood vessels), which significantly increase the surface of the layer. The synovial membrane produces a fluid that moisturizes the articulating articular surfaces, eliminating their friction against each other. In addition, this shell absorbs liquid, ensuring a continuous metabolic process.

If the articular surfaces do not match, there are cartilaginous plates of different shapes between them - articular discs and menisci. They are able to shift during movements, smooth out the irregularities of the articulating surfaces and perform a shock-absorbing function.

In some cases (for example, the shoulder joint) along the edge of the articular surface in one of the bones is located articular lip, which deepens it, increases the area of ​​the joint, gives a greater conformity to the shape of the articulating surfaces.

Depending on the structure of the articulating surfaces in the joints, movements can be made around different axes. bending And extension - these are movements around the frontal axis; abduction And cast - around the sagittal axis; rotation - around the longitudinal axis; circular rotation - around all axes. The amplitude and range of movements in the joints depend on the difference in the angular degrees of the articulating surfaces. The greater this difference, the greater the range of motion.

By the number of articulating bones, the shape of their articular surfaces, the joints may differ from each other.

A joint formed by only two articular surfaces is called simple, and a joint of three or more articular surfaces - difficult.

There are complex and combined joints. The former are characterized by the presence of an articular disc or meniscus between the articulating surfaces; the latter are represented by two anatomically isolated joints that act together (temporomandibular joint).

According to the shape of the articular surfaces, the joints are divided into cylindrical, elliptical and spherical (Fig. 10).

Rice. 10. Joint shapes:

1 - block-shaped; 2 - elliptical; 3 - saddle; 4 - globular

There are also variants of the above forms of joints. For example, a type of cylindrical joint is a block-shaped joint, a spherical joint is a bowl-shaped and flat joint. The shape of the articular surfaces determines the axes around which movement occurs in a given joint. With a cylindrical shape of the articular surfaces, the movement is carried out around one axis, with an elliptical shape - around two axes, with a spherical shape - around three or more mutually perpendicular axes. Thus, there is a certain relationship between the shape of the articular surfaces and the number of axes of movement. In this regard, one-, two- and three-axis (multi-axial) joints are distinguished.

TO uniaxial joints are cylindrical and block-shaped. For example, in cylindrical joint rotation occurs around the vertical axis, which coincides with the axis of the bone (rotation of the 1st cervical vertebra together with the skull around the odontoid process of the 2nd vertebra). IN trochlear joints rotation occurs around one transverse axis, for example, flexion and extension in the interphalangeal joints. The screw joint also belongs to the block-shaped joint, where the movement is carried out in a spiral (shoulder-ulnar joint).

TO biaxial joints include elliptical, saddle and condylar joints. IN elliptical joint movements occur around mutually perpendicular axes (for example, the wrist joint) - flexion and extension around the frontal axis, adduction and abduction - around the sagittal axis.

IN saddle joint(carpometacarpal joint of the thumb of the hand) movements occur similar to those in the elliptical joint, that is, not only abduction and adduction, but also opposition of the thumb to the rest.

Condylar joint (knee joint) is a transitional form between block-shaped and elliptical. It has two convex articular heads that resemble the shape of an ellipse and are called condyles. In the condylar joint, movement around the frontal axis is possible - flexion and extension, around the longitudinal axis - rotation.

Triaxial (multi-axial) include spherical, bowl-shaped And flat joints. In the ball-and-socket joint, flexion and extension, adduction and abduction, and rotation occur. As a result of a significant difference in the size of the articular surfaces (the head of the joint and the articular cavity), the spherical (shoulder) joint is the most mobile among all joints.

Cup joint (hip joint) is a type of spherical joint. It differs from the latter by a greater depth of the articular cavity. Due to the small difference in the angular dimensions of the articular surfaces, the range of motion in this joint is small.

In flat joints, movements are carried out around three axes, but the amplitude of rotation is limited due to the slight curvature and size of the articular surfaces. Flat joints include arcuate (intervertebral), tarsal-metatarsal joints.

Separate bones in the human body are connected to each other into a single skeleton by muscles, ligaments, cartilage. They give it shape and strength, and in most cases mobility. Almost all bones in the human body are directly articulated with each other.

Types of bone connection

There are 3 bones: fixed, semi-movable and movable. And the degree of mobility directly depends on the type and structure of the tissue located between the bones. It can bind them quite rigidly, provide limited connection flexibility or a wide range of motion:

1. The fixed connection of bones tends to be formed by their fusion, it is characterized by limited movements, its complete absence or slight mobility.
2. Semi-movable connections exist between fixed and moving connections.
3. The movable joints include joints, they are responsible for the mechanics of movement in the body.

Fixed connection

The fixed connection of bones has a human skull and pelvis. In them, between the joints, there is a thin layer of connecting suture or cartilage. Given the shape of the connection, there are jagged, scaly and flat seams. All of them are the area of ​​development of the bones of the skull and reveal a shock-absorbing effect during movements.

Due to the fact that the fixed connection of the bones has a skull, its bones protect the brain and sensory organs from external influences, and also form facial features. The only exceptions are the movable temporomandibular joints, which connect the lower jaw to the skull.

The structure of the bones of the skull

There are 2 important sections in the skull:

• One of them, the brain, is built from 8 bones that protect the brain and inner ear. All of his bones are interconnected by layers of fibrous tissue - sutures.
• And the facial consists of 14 bones, where the nose, mouth and eyes are located. The bones of the facial region determine the facial features of a person. The nasal cavity is divided into two symmetrical halves by an osteochondral septum. Bone outgrowths called cause the flow of incoming air to warm up and be filtered, leaving dust and microbes on the mucosa. They also open here

The fixed connection of the bones has a thin layer of fibrous tissue, which acts as a glue. It is a dense fibrous formation that makes them immobile. This fixed connection of bones is called synarthrosis. Synarthroses are found in the skull, for example, its sutures, which have connective tissue between them. This is how the bones of the skull and teeth with the sockets of the jaws are combined with each other.

Semi-movable connections

A person has 7 cervical vertebrae, of which two upper ones stand out: atlas and axial. The atlas is a ring vertebra that bears the entire weight of the human skull. Its name, by the way, is dedicated to the mythical titan holding the vault of heaven on his shoulders. It is thanks to the articulation of the atlas with the skull that a person can nod. And the axial vertebra, or epistrophy, forms a tooth on top, around which the atlas rotates along with the skull.

The semi-movable joint of the bones is cartilaginous tissue, but there is a small cavity in the thickness of the cartilage. The limited mobility of these joints arises due to the cartilaginous plates and elastic ligaments.

Synchondroses are semi-movable joints between bones with a very low degree of mobility. Cartilage joints have limited mobility due to the elasticity of the cartilage that binds the bones. For example, a semi-movable connection of bones has a pelvis closing in front, and intervertebral discs. In cartilage tissue, the cells are separated by an intercellular substance, which often forms a strong framework that allows it to perform binding, supporting and protective functions.

cartilage connections

There are several types of cartilage:

1. Hyaline (glassy) - the most common. It is very strong, smooth, bluish tint. It forms the skeleton of the embryo, and in adults - part of the ribs, the support of the respiratory tract and the articular surfaces of the articulated bones. Interestingly, the skeleton of the fetus consists mainly of such flexible cartilage, which gradually develops into bone tissue. Remains of cartilage between the diaphysis and epiphyses ossify only by the age of 25. In addition, not all skeletal cartilage ossifies. It remains on the articular surfaces of bones, in the nose and
2. Fibrous (fibrous) - whitish in color. Contains more collagen fibers and forms joints with limited mobility, such as connecting intervertebral discs. These cartilaginous intervertebral discs can be slightly compressed and twisted, but due to their multiplicity they provide flexibility to the spine.
3. Elastic (mesh) - yellowish in color. It is characterized by a large number of elastin fibers, which gives it flexibility. Forms the skeleton of the auricle and part of the larynx.

Collagen is a very strong and flexible material that forms the basis of most of the connective tissues that bind, separate and protect vital organs. These include bone, cartilage, fibrous tissue.

Fixed connection of bones: examples

Speaking of the immovable connection of bones, one must dwell on synostoses, which are formed from syndesmoses and synchondroses with age. In this case, the connective tissue or cartilage between some bones turns into bone.

So, the bones of the pelvic girdle are an example of which bone joints are immovable. They form something in the form of a bowl that protects and supports the organs of the lower part of the abdominal cavity. This belt can withstand huge loads, the hollow of the hip joint is much deeper than the shoulder joint, so it is much more stable.

For example, the coccyx consists of 3-5 rudimentary vertebrae, which fuse with age into a single triangular bone. Another example of synostosis is overgrown sutures or a fontanel in an infant. These are physiological synostoses.

But with some diseases of the bone apparatus, ossification can occur not only in cartilage tissue, but also in some joints. These are pathological synostoses. Naturally, movements with such ossification are absent.

Introduction

Physiology is the science of functions, i.e. about the vital activity of organs, systems and the organism as a whole. Its ultimate goal is the knowledge of functions, which would provide the possibility of active influence on them in the desired direction.

The value of the musculoskeletal system is very high. The supporting function is that the skeleton supports all other organs, gives the body a certain shape and position in space. The musculoskeletal system is presented in the form of two systems - bone and muscle.

Bones, connected by cartilage, ligaments, as well as muscles attached to them, form cavities (receptacles) in which vital organs are located. This is a protective function of the musculoskeletal skeleton. The motor function is carried out mainly by muscles.

Of no small importance to the musculoskeletal system are exercises for the development of movement. These classes allow us to maintain our body in the right shape, improve and develop various abilities.

Types of bones. Types of bone connection

The bones that make up the skeleton make up approximately 18% of the total body weight.

The classification of bones is currently carried out not only on the basis of their structure, but also on the basis of function and development. As a result, there are tubular, spongy, flat and mixed bones.

Tubular bones carry the function of support, protection and movement. They are shaped like a tube with a medullary canal inside. The relatively thinner middle part of the tubular bones is called the body or diaphysis, and the thickened ends are called the epiphyses. The thickening of the ends of long tubular bones is functionally substantiated. The epiphyses serve as the junction of bones with each other, here muscle attachment occurs. The wider the contact surface of the bones, the stronger; more stable connection. At the same time, the thickened epiphysis moves the muscle away from the long axis of the bone, as a result of which the latter approaches the site of attachment at a large angle. This, according to the rule of parallelogram of forces, increases the efficiency of the muscle. Tubular bones are divided into long and short.

Long bones, the length of which significantly exceeds their other sizes, make up the proximal links of the skeleton of both limbs.

Short bones are located in the metacarpus, metatarsus, phalanges, t. where at the same time greater strength and mobility of the skeleton are needed.

Spongy bones are divided into long, short, sesamoid.

Long spongy bones (ribs, sternum) consist mainly of a spongy substance covered with a compact substance, they have the function of support and protection.

Short spongy bones (vertebrae, bones of the wrist, tarsus) consist mainly of spongy substance, serve as a support.

Sesamoid bones (patella, pisiform bone, sesamoid bones of the fingers and toes) consist of spongy substance, develop in the thickness of the tendons, strengthen the latter and serve as a block through which they are thrown. This increases the leverage of muscle force application and creates more favorable conditions for its work. Sesamoid bones got their name for their resemblance to sesame seeds.

Flat bones form the walls of cavities containing internal organs. Such bones are curved on one side, convex on the other; their width and length significantly predominate over their thickness. These are the pelvic bone, scapula, bones of the brain skull.

Mixed bones lie at the base of the skull, have a different shape and development, the complexity of which corresponds to the variety of functions performed.

Among the flat and mixed bones of the skull, there are air-bearing ones, containing a cavity lined with a mucous membrane and filled with air, which lightens the bones without compromising their strength.

The relief of the bone surface is not the same and is due to the mechanical action of neighboring organs. The vessels and nerves adjacent to the skeleton, the muscles and their tendons leave traces on the bones in the form of grooves, notches, holes, roughness and channels. Areas on the surface of the bone, free from attachment of muscles and ligaments, as well as articular surfaces covered with hyaline cartilage, are completely smooth. The surfaces of the bones in the places of attachment of strong muscles to them are elongated in the form of tuberosities, tubercles and processes, increasing the area of ​​attachment. Therefore, in people whose profession is associated with the implementation of a large physical load, the surfaces of the bones are more uneven.

The bone, with the exception of the connecting surfaces, is covered with periosteum. This is a thin connective tissue sheath, which is rich in nerves and blood vessels that penetrate from here into the bone through special openings.

Through the periosteum, bone nutrition and its innervation are carried out. The value of the periosteum lies in facilitating the attachment of the muscles and ligaments that are woven into its outer layer, as well as in softening the shocks. The inner layer of the periosteum contains bone-forming cells - osteoblasts, which ensure the growth of developing young bones in thickness.

In bone fractures, osteoblasts form a callus that connects the ends of a broken bone, restoring its integrity.

Classification of compounds. The mobility of parts of the skeleton depends on the nature of the joints of the bones. The apparatus connecting the bones develops from the mesenchyme, which lies between the rudiments of these bones in the embryo. There are two main types of bone connections: continuous and discontinuous, or joints. The former are more ancient: they are found in all lower vertebrates and in the embryonic stages of higher ones. When bones are laid in the latter, their original material (connective tissue, cartilage) is preserved between them. With the help of this material, the bones are fused, i.e., a continuous connection is formed. At later ontogenetic stages, more perfect, discontinuous connections appear in terrestrial vertebrates. They develop due to the appearance of a gap in the original material preserved between the bones. Remnants of cartilage cover the articulating surfaces of the bones. There is a third, intermediate type of joints - a semi-joint.

Continuous connections. A continuous connection - synarthrosis, or fusion - occurs when the bones are connected to each other by a continuous layer connecting their tissues. Movement is limited or non-existent. By the nature of the connective tissue, there are connective tissue adhesions, or syndesmoses, cartilaginous adhesions, or synchondrosis, and adhesions with the help of bone tissue - synostoses.

Syndesmoses are of three kinds: 1) interosseous membranes, for example, between the bones of the forearm or lower leg; 2) ligaments connecting bones (but not associated with joints), for example, ligaments between the processes of the vertebrae or their arches; 3) seams between the bones of the skull. Interosseous membranes and ligaments allow some displacement of the bones. In the seams, the layer of connective tissue between the bones is insignificant and movements are impossible.

Synchondrosis is, for example, the connection of the 1st rib with the sternum by means of costal cartilage, the elasticity of which allows some mobility of these bones.

Discontinuous connections - diarthrosis, articulation, or joint, characterized by the presence of a small space (gap) between the ends of the connecting bones. There are simple joints, formed by only two bones (for example, the shoulder joint), complex, when a larger number of bones are included in the joint (for example, the elbow joint), and combined, allowing movement only simultaneously with movement in other, anatomically separate, joints (for example, the proximal and distal radioulnar joints). The obligatory structural formations of the joint include the articular surfaces, the articular bag, or capsule, and the articular cavity.

In addition to the mandatory ones, auxiliary formations can occur in the joint. These include articular ligaments and lips, intra-articular discs and menisci.

There are two types of bone connections - continuous and discontinuous.

1. Continuous connection of bones– synarthrosis -synarthrosis . Depending on what tissue connects the bones, there are five types of synarthrosis: synsarcosis, synelastosis, syndesmosis, synchondrosis, synostosis.

Synsarcosis– synsarcosis - the connection of bones through muscles.

synelastosis– synelastosis - the bones are connected using elastic tissue that can be highly stretched and resist rupture. Synelastoses include the supraspinous and nuchal ligaments.

syndesmosis– syndesmosis bones are connected by dense connective (fibrous) tissue. Its collagen fibers are soldered by loose connective tissue into bundles, strands or membranes. Syndesmoses occur as ligaments, membranes, sutures and impaction.

Bundle – ligamentum- Formed by bundles of collagen fibers moving from one bone to another.

Membrane – membrane- consists of bundles of collagen fibers that form thin plates between the bones (for example, the membrane in the occipito-atlantic joint).

The seam –sutura- a special type of connection of the lamellar bones of the skull. Connective tissue is located in the form of a very thin layer between two connecting bones. According to the structure of the contacting surfaces of the bones, it distinguishes sutures: flat, serrated, foliate, scaly.

flat seam –sutura plana- when the edges of the connecting bones have smooth surfaces. Such a connection is characterized by fragility and therefore, during digestion or maceration, the bones are easily separated from the skeleton (the connection of the nasal bones to each other, especially in ruminants).

notched seam –sutura serrata (from serra- saw)- the jagged edges of the connecting bones enter into each other (the connection of the nasal bones with the frontal or frontal bones with the parietal). The serrated seam is very durable.

Leaf seam –sutura foliata(fromfolia- sheet)- in shape it resembles a dentate, but its individual teeth in the form of a woody leaf are deeply embedded in the edge of the adjacent bone (the connection of the wings of the sphenoid bone with the frontal and parietal bones). This connection is highly durable.

Scale seam –sutura squamosa(from squama – scales ) - when the edges of the bones overlap each other, like the scales of a fish (connection of the parietal bone with the scales of the temporal bone).

Injection – gomphosis ( from gomphos – nail ) - characteristic for the connection of teeth with the incisor, maxillary and mandibular bones, when each tooth, located in the alveolar recess, has a dental ligament ( lig. dentale), which is the periosteum, or periodontium ( periodontum, from peri– around + odontos- tooth) and which is common to both the alveoli and the root of the tooth.

Synchondrosis–synchondrosis - bones are connected by cartilage tissue - hyaline or fibrous. In synchondroses without great mobility, there is hyaline cartilage, for example, in the joints between the epiphyses and the diaphysis of the tubular bones of young animals. In the presence of high mobility in synchondrosis, there is fibrous cartilage in the form of discs, for example, between the vertebrae.

Connections of bones through connective and cartilaginous tissue with age of animals can ossify. This bone connection is called synostosis–synostosis .

Bone mobility in synarthrosis depends primarily on the physical properties of the connective tissue. Thus, maximum mobility is observed in synsarcosis, followed by synelastosis, syndesmosis and synchondrosis in descending order. There is no mobility in synostoses.

2. Discontinuous connection of bones–diarthrosis–diarthrosis or a jointarticulation .

The joint is characterized by the presence of a slit-like cavity between the bones. Joints connect bones that perform the function of movement.

Mandatory structural elements of the joint:

articular surfaces - facies articulares.

Articular cartilage - cortilago articularis.

joint capsule - capsula articularis.

articular cavity - cavum articulare.

joint fluid - sinovia.

Auxiliary joint formations:

Intra-articular ligaments ligamentum interarticulares.

Articular lips (hip joint) - labia articulares.

articular discs - discus articulares.

Articular menisci - meniscus articulares.

Sesamoid bones – ossa articulares.

Articular surfaces – facies articulares - formed by two or more articulating bones. The relief of the articular surfaces to a certain extent affects the volume and functional functions of the joints. Articular surfaces covered with articular cartilage are usually congruent, i.e. congruent (from congruo- converge, coincide) and in rare cases - mismatched, or incongruent. Incongruence is eliminated due to intra-articular inclusions - articular lips, discs, menisci.

articular cartilage – cartilago articularis - covers the articular surfaces of bones. According to the type of structure, it is hyaline, having a smooth surface, reduces friction between the bones.

joint capsule–ca psula articularis - consists of two membranes: outer (fibrous) and inner (synovial). The fibrous membrane of the capsule is a continuation of the periosteum, which passes from one bone to another. The synovial membrane is built of loose connective tissue, it is rich in blood vessels and nerves, and from the side of the articular cavity is lined with one or more layers of connective tissue cells that secrete synovial fluid into the cavity.

Articular cavity – cavum articulare - is a slit-like space between the articular surfaces and the ends of the articulating bones, surrounded by a joint capsule. It is sealed and contains a small amount joint fluid.

Joint fluid, or synovia-si novia - has a yellow color, is transparent and has a significant viscosity. Synovia performs various functions: lubricates the articular surfaces of bones, thereby reducing friction between them; serves as a nutrient medium for articular cartilage; plays a buffering role.

By structure, the joints are of two types:

1. Simple joints -articulation simplex , in the formation of which only two bones participate.

2. Complex joints -articulation composite formed by more than two articulating bones or contain auxiliary formations in their joint (intra-articular ligaments, menisci, discs, sesamoid bones).

It also distinguishes combined joints, when movement is carried out simultaneously in several joints, as, for example, in paired jaw joints, in the occipito-atlantic and atlant-axial joints.

By function, the joints are divided into uniaxial, biaxial and multiaxial.

In uniaxial joints, movement occurs around one axis: bending -f l exi o And extension -extensio . According to the shape of the articular surface, these joints can be block-shaped, helical and rotational.

In biaxial joints, movement occurs along two axes perpendicular to each other: along the segmental axis - flexion and extension, along the sagittal axis - abduction -abductio And cast -adductio . By the nature of the articular surface of the bones, biaxial joints can be ellipsoidal and saddle-shaped.

In multiaxial joints, movement is possible along many axes, since the articular surface on one of the bones represents part of the ball, and on the other, the corresponding fossa. Such a joint is called spherical (for example, the shoulder and hip joints). In this type of joints, movements are possible: along the segmental axis - extension and flexion, along the sagittal axis - abduction and adduction. Along an axis drawn longitudinally through the center of the bone, movements are possible: rotation -rotation ; outward rotation - supination -supinatio ; inward rotation - pronation -pronatio .

Questions to consolidate the studied material.

Types of bone joints and their varieties.

What is typical for continuous connections?

What is syndesmosis, suture, hammering, synchondrosis, symphysis, synsarcosis and their characteristic differences.

What is characteristic of discontinuous connections?

The main structural components of a discontinuous connection.

Classification of joints and their morphological characteristics.

Ligaments of joints and their varieties.

Intra-articular inclusions and their characteristics.

Combined joints and their characteristics.

Types of seams and their characteristics (with examples).

Factors affecting the development, structure and specialization of bone joints.

Practical value of knowledge of artrology for biology, zootechnics, veterinary medicine?