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 joints there is little or no movement; discontinuous joints are movable.

The main types of continuous connections are syndesmoses and synchondroses (Fig. 16).

Syndesmoses are called connections between bones using fibrous connective tissue. They will look at them ligaments(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 type of syndesmosis are sutures - connections of the bones of the skull through thin layers of fibrous connective tissue.

Synchondroses are called connections between bones using cartilage tissue. An example of synchondrosis is the connection of 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) is 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(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 fibrocartilage.

The articular capsule (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. The 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).

There is a relationship between the nature of movements in the joints and the shape of the articular surfaces. Articular surfaces are compared to segments of geometric figures. According to the shape of the articular surfaces, joints are divided into spherical, ellipsoidal, saddle-shaped, cylindrical And block-shaped(Fig. 17). When determining movements in joints, three main axes are mentally drawn: transverse, anteroposterior, or sagittal, and vertical. The following basic movements are distinguished: around the transverse axis - bending(inflection) and extension(extension); around the sagittal axis - lead(abduction) and casting(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 - ellipsoidal 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 sliding is possible in them. The joint is called simple, if it is formed by two bones, and complex, if three or more bones connect in it. Two or more joints, in which movements can only occur simultaneously, together constitute 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 connections are divided into three types: continuous, discontinuous and symphysis. Depending on the type of tissue that connects the bones, the following types of continuous connections are distinguished: fibrous, bone and synchondrosis (cartilaginous connections) (Fig. 9).

Rice. 9. Types of bone connections (diagram):

A - joint; B - fibrous junction; IN - synchondrosis (cartilaginous junction); 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 great strength and low mobility. These include syndesmoses (ligaments and interosseous membranes), sutures and impaction.

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

Interosseous membranes connect the diaphyses of the tubular bones and serve as a place for muscle attachment. The interosseous membranes have holes through which blood vessels and nerves pass.

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

Injection - a special type of fibrous compound that is observed at the connection of the tooth with the bone tissue of the dental alveolus. Between the tooth and the bone wall there is a thin layer of connective tissue - paradont.

Synchondroses - connecting bones with cartilage tissue. They are characterized by elasticity and strength; they perform a shock-absorbing function.

The replacement of the cartilaginous layer between bones with bone tissue is called synostosis. Mobility in such joints disappears, and strength increases.

Discontinuous (synovial or articular) joints are the most mobile joints of bones. They have great mobility and variety of movements. The characteristic features of a joint are the presence of articular surfaces, an articular cavity, synovial fluid and a 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 articular capsule covers the connecting ends of the bones, forms a sealed sac, the walls of which have two layers: the outer - fibrous and the inner - synovial membrane.

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

Inner layer (synovium) has small outgrowths (villi rich in blood vessels), which significantly increase the surface of the layer. The synovium produces fluid that moisturizes the articular surfaces of the joints, eliminating their friction against each other. In addition, this membrane 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 unevenness of 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 there is labrum, which deepens it, increases the area of ​​the joint, and gives greater conformity to the shape of the articulating surfaces.

Depending on the structure of the articulating surfaces, movements in the joints can occur around different axes. Flexion And extension - these are movements around the frontal axis; lead And casting - 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 angular degrees of the articulating surfaces. The greater this difference, the greater the range of movements.

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

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

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, joints are divided into cylindrical, ellipsoidal and spherical (Fig. 10).

Rice. 10. Joint shapes:

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

There are also variants of the above joint forms. For example, a type of cylindrical joint is a trochlear joint, a spherical joint is a cup-shaped and flat joint. The shape of the articular surfaces determines the axes around which movement occurs at a given joint. With a cylindrical shape of the articular surfaces, movement occurs around one axis, with an ellipsoidal 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 motion. In this regard, one-, two- and three-axial (multi-axial) joints are distinguished.

TO uniaxial joints include cylindrical and block-shaped. For example, in cylindrical joint rotation occurs around a vertical axis, which coincides with the axis of the bone (rotation of the first cervical vertebra together with the skull around the odontoid process of the second vertebra). IN trochlear joints rotation occurs around one transverse axis, for example, flexion and extension at the interphalangeal joints. The trochlear joint also includes a screw joint, where movement occurs in a spiral (humeral-ulnar joint).

TO biaxial joints include the ellipsoid, 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) movements occur similar to movements in the ellipsoid joint, i.e. not only abduction and adduction, but also opposition of the thumb to the rest.

Condylar joint (knee joint) It is a transitional shape between block-shaped and ellipsoid. 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 (multiaxial) include spherical, cup-shaped And flat joints. The ball and socket joint undergoes flexion and extension, adduction and abduction, and rotation. As a result of the significant difference in the size of the articular surfaces (the head of the joint and the glenoid cavity), the ball-and-socket joint is the most mobile of all joints.

Cup joint (hip joint) is a type of ball and socket joint. It differs from the latter in the greater depth of the glenoid 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. The flat joints include the facet (intervertebral) and tarsometatarsal joints.

Individual bones in the human body are connected to each other into a single skeleton by muscles, ligaments, and 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 connections

There are 3 types of bones: immobile, 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 completely rigidly, provide limited flexibility of the connection or a wide range of movements:

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

Fixed connection

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

Due to the fact that the skull has a fixed connection of bones, 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 skull bones

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 its bones are connected to each other 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 a person's facial features. The nasal cavity is divided into two symmetrical halves by an osteochondral septum. The so-called bone outgrowths force the flow of incoming air to warm up and filter, leaving dust and microbes on the mucous membrane. They also open here

The fixed joint of the bones has a thin layer of fibrous tissue that acts as glue. It is a dense fibrous formation that makes them immobile. This immobile connection of bones is called synarthrosis. Synarthrosis occurs 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-moving joints

A person has 7 cervical vertebrae, of which the upper two stand out: the atlas and the 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 epistropheus, 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 in the thickness of the cartilage there is a small cavity. The limited mobility of these joints occurs due to 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 connects the bones. For example, a semi-movable joint of bones has a pelvis and intervertebral discs closing in front. In cartilage tissue, cells are separated by an intercellular substance, which often forms a strong framework that allows it to perform binding, supporting and protective functions.

Cartilaginous connections

There are several types of cartilage:

1. Hyaline (vitreous) is the most common. It is very durable, smooth, bluish in color. It forms the skeleton of the embryo, and in adults - part of the ribs, support of the respiratory tract and articular surfaces of the articulated bones. Interestingly, the fetal skeleton consists mainly of such flexible cartilage, which gradually develops into bone tissue. The 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, for example connecting intervertebral discs. These cartilaginous intervertebral discs can be slightly compressed and twisted, but due to their number, they provide flexibility to the spine.
3. Elastic (mesh) - yellowish in color. It is distinguished 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 serves as the basis of most connective tissues that bind, separate and protect vital organs. These include bone, cartilage, and fibrous tissue.

Fixed connection of bones: examples

Speaking about the fixed connection of bones, we need to dwell on synostoses, which are formed from syndesmoses and synchondroses with age. In this process, the connective tissue or cartilage between some bones turns into bone.

So, the bones of the pelvic girdle are an example of which bone connections are immobile. They form something of a cup that protects and supports the organs of the lower abdominal cavity. This belt can withstand enormous loads, the socket 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 grow together 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 skeletal system, ossification may occur not only of cartilage tissue, but also of some joints. These are pathological synostoses. Naturally, there are no movements with such ossification.

Introduction

Physiology is the science of functions, i.e. about the vital functions of organs, systems and the body as a whole. Its ultimate goal is knowledge of functions, which would provide the possibility of actively influencing them in the desired direction.

The importance of the musculoskeletal system is very great. The supporting function is that the skeleton supports all other organs and 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 (containers) in which vital organs are located. This is a protective function of the musculoskeletal skeleton. The motor function is carried out mainly by muscles.

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

Types of bones. Types of bone connections

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

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

Tubular bones have 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 epiphyses. The thickening of the ends of long tubular bones is functionally justified. The epiphyses serve as the junction of bones with each other, and muscle attachment occurs here. The wider the surface of contact between the bones, the stronger it is; 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 attachment site at a large angle. This, according to the rule of parallelogram of forces, increases the force of the beneficial action of the muscle. Tubular bones are divided into long and short.

Long bones, the length of which significantly exceeds their other dimensions, constitute the proximal parts of the skeleton of both limbs.

Short bones are located in the metacarpus, metatarsus, phalanges, etc. where greater strength and mobility of the skeleton are simultaneously required.

Spongy bones are divided into long, short, and sesamoid.

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

Short spongy bones (vertebrae, carpal bones, tarsals) consist mainly of spongy substance and serve as 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 shoulder for applying muscle force and creates more favorable conditions for its work. Sesamoid bones got their name from their resemblance to sesame seeds.

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

Mixed bones lie at the base of the skull, have different shapes 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, which contain a cavity lined with mucous membrane and filled with air, which makes the bones lighter without compromising their strength.

The surface relief of the bone is not the same and is determined by the mechanical influence of neighboring organs. The vessels and nerves adjacent to the skeleton, muscles and their tendons leave marks on the bones in the form of grooves, notches, holes, roughnesses and channels. Areas on the surface of the bone that are 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 places where strong muscles are attached to them are elongated in the form of tubercles, tubercles and processes that increase the area of ​​attachment. Therefore, in people whose profession involves performing heavy physical activity, 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 membrane that is rich in nerves and vessels that penetrate from here into the bone through special openings.

Through the periosteum, the bone is nourished and innervated. The importance of the periosteum is to facilitate the attachment of muscles and ligaments that are woven into its outer layer, as well as to soften shocks. The inner layer of the periosteum contains bone-forming cells - osteoblasts, which ensure the growth of developing young bones in thickness.

When bones are fractured, osteoblasts form a callus that connects the ends of the 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 lying between the rudiments of these bones in the embryo. There are two main types of bone joints: continuous and discontinuous, or joints. The first are more ancient: they are found in all lower vertebrates and in the embryonic stages of higher ones. When bones are formed in the latter, their original material (connective tissue, cartilage) is preserved between them. With the help of this material, bone fusion occurs, i.e., a continuous connection is formed. At later ontogenetic stages, more advanced, discontinuous connections arise 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 bones. There is a third, intermediate type of joint - a semi-joint.

Continuous connections. A continuous connection - synarthrosis, or fusion - occurs when the bones are connected to each other by a continuous layer of tissue connecting them. Movements are limited or completely absent. According to the nature of the connective tissue, connective tissue fusions, or syndesmoses, cartilaginous fusions, or synchondrosis, and fusions with the help of bone tissue - synostoses are distinguished.

Syndesmoses are of three types: 1) interosseous membranes, for example, between the bones of the forearm or lower leg; 2) ligaments connecting bones (but not connected to joints), for example, ligaments between the processes of the vertebrae or their arches; 3) sutures between the bones of the skull. Interosseous membranes and ligaments allow some displacement of the bones. At the sutures, the layer of connective tissue between the bones is insignificant and movement is impossible.

Synchondrosis is, for example, the connection of the first rib with the sternum through the costal cartilage, the elasticity of which allows some mobility of these bones.

Discontinuous joints - diarthrosis, articulation, or joint, is 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 the joint includes a larger number of bones (for example, the elbow joint), and combined, allowing movement only simultaneously with movement in other, anatomically separate joints (for example, proximal and distal radioulnar joints). The obligatory structural formations of the joint include the articular surfaces, the articular capsule, or capsule, and the articular cavity.

In addition to the obligatory ones, auxiliary formations may be found in the joint. These include articular ligaments and lips, intraarticular discs and menisci.

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

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

Synsarcosis– synsarcosis - connection of bones through muscles.

Synelastosis– synelastosis – bones are connected by elastic tissue that can stretch greatly and resist tearing. Synelastosis includes the supraspinous and nuchal ligaments.

Syndesmosis– syndesmosis – bones are connected by dense connective (fibrous) tissue. Its collagen fibers are fused by loose connective tissue into bundles, cords or membranes. Syndesmoses occur in the form ligaments, membranes, sutures and impactions.

Bunch – ligamentum– formed by bundles of collagen fibers running from one bone to another.

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

The seam –sutura- a special type of connection of the lamellar bones of the skull. Between the two connecting bones there is a very thin layer of connective tissue. Based on the structure of the contacting surfaces of bones, it distinguishes sutures: flat, jagged, leafy, scaly.

Flat seam –sutura plana– when the edges of the connecting bones have smooth surfaces. This 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 with each other, especially in ruminants).

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

Leaf seam –sutura foliata(fromfolia– sheet)- in shape it is similar to the dentate, but its individual teeth in the form of a tree 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 very durable.

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

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

Synchondroses–synchondrosis – bones are connected by cartilaginous tissue – hyaline or fibrous. In synchondroses without great mobility there is hyaline cartilage, for example, in the connections between the epiphyses and diaphysis of the tubular bones of young animals. If there is great mobility in the synchondrosis, there is fibrous cartilage in the form of discs, for example, between the vertebrae.

The connections of bones through connective and cartilaginous tissue can ossify as animals age. This bone connection is called synostosis–synostosis .

Bone mobility during synarthrosis depends, first of all, on the physical properties of the connecting tissue. Thus, maximum mobility is observed in synsarcosis, followed in descending order by synelastosis, syndesmosis and synchondrosis. There is complete absence of mobility in synostoses.

2. Discontinuous connection of bones–diarthrosis–diarthrosis or joint -articulatio .

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 formations of joints:

Intra-articular ligaments - ligamentum interarticulares.

Articular labrum (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 influences the volume and functional functions of the joints. The articular surfaces covered with articular cartilage are usually coincident, i.e. congruent (from congruo– I agree, I coincide) and in rare cases – discrepant, or incongruent. Incongruity 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 shell 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 on the side of the articular cavity it is lined with one or several layers of connective tissue cells, which 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 the joint capsule. It is sealed and contains a small amount joint fluid.

Joint fluid, or synovium–si novia – has a yellow color, is transparent and has 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 buffer role during support.

There are two types of joints according to their structure:

1. Simple joints –articulatio simplex , in the formation of which only two bones are involved.

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

There is also a distinction between combined joints, when movement is carried out simultaneously in several joints, such as, for example, in paired joints of the jaws, in the occipito-atlas and atlanto-axial joints.

According to their function, joints are divided into uniaxial, biaxial and multiaxial.

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

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

In multiaxial joints, movement is possible along many axes, since the articular surface on one of the bones represents part of a ball, and on the other, the corresponding fossa. Such a joint is called a ball-and-socket joint (for example, the shoulder and hip joints). In this type of joint, 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 reinforce the material studied.

Types of bone connections and their varieties.

What are the characteristics of continuous connections?

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

What are the characteristics of discontinuous connections?

Main structural components of a discontinuous connection.

Classification of joints and their morphological characteristics.

Joint ligaments and their types.

Intra-articular inclusions and their characteristics.

Combined joints and their characteristics.

Types of seams and their characteristics (with examples).

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

Practical significance of knowledge of arthrology for biology, animal science, veterinary medicine?