Have you ever thought about what joints are? What role do they play in the human body? With their help, we can make any movements: sit, stand, run, dance, play sports, etc. There are a number of them in the human body huge amount and each is responsible for a specific area. To learn more about the structure of the joint, its features and types, we suggest you read our article.

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Anatomical features

Human joints are the basis of every body movement. They are found in all bones of the body (the only exception is hyoid bone). Their structure resembles a hinge, due to which the bones slide smoothly, preventing their friction and destruction. A joint is a movable connection of several bones, and in the body there are more than 180 of them in all parts of the body. They are immobile, partially movable, and the main part is represented by movable joints.

The degree of mobility depends on the following conditions:

• volume of connecting material;
• type of material inside the bag;
• shapes of bones at the point of contact;
• the level of muscle tension, as well as ligaments inside the joint;
• their location in the bag.

How is the joint structured? It looks like a bag of two layers that surrounds the junction of several bones. The bag ensures the tightness of the cavity and promotes the production synovial fluid. It, in turn, acts as a shock absorber for bone movements. Together they perform three main functions of the joints: they help stabilize the body position, are part of the process of movement in space, and ensure the movement of parts of the body in relation to each other.

Basic elements of a joint

The structure of human joints is complex and is divided into the following basic elements: cavity, capsule, surface, synovial fluid, cartilage, ligaments and muscles. We'll talk briefly about each below.

• The joint cavity is a slit-like space, which is hermetically sealed and filled with synovial fluid.
• Joint capsule - consists of connective tissue, which envelops the connecting ends of the bones. The capsule is formed on the outside from a fibrous membrane, but inside it has a thin synovial membrane (a source of synovial fluid).
• Articular surfaces have special form, one of them is convex (also called the head), and the second is pit-shaped.

• Synovial fluid. Its main function is to lubricate and moisturize surfaces; it also plays an important role in fluid exchange. It is a buffer zone during various movements (pushing, jerking, squeezing). Provides both sliding and divergence of bones in the cavity. A reduction in the amount of synovium leads to a number of diseases, bone deformations, and loss of a person’s ability to perform normal functions. physical activity and, as a result, even disability.
• Cartilage tissue (thickness 0.2 - 0.5 mm). The surfaces of the bones are covered with cartilage tissue, the main function of which is shock absorption during walking and sports. The anatomy of cartilage is represented by connective tissue fibers that are filled with fluid. This, in turn, nourishes the cartilage when it is at rest, and during movement it releases fluid to lubricate the bones.
• Ligaments and muscles are auxiliary parts of the structure, but without them the normal functionality of the entire body is impossible. With the help of ligaments, bones are fixed without interfering with movements of any amplitude due to their elasticity.

The inert protrusions around the joints also play an important role. Their main function- limitation of range of motion. As an example, consider the shoulder. IN humerus there is a bony tubercle. Due to its location next to the process of the scapula, it reduces the range of motion of the arm.

Classification and types

In development human body, way of life, mechanisms of human interaction and external environment, the need to perform various physical actions and the result was a variety of types of joints. The classification of joints and its basic principles are divided into three groups: the number of surfaces, the shape of the end of the bones, and functionality. We'll talk about them a little later.

The main type in the human body is the synovial joint. His main feature- connection of bones in the bag. This type includes shoulder, knee, hip and others. There is also a so-called facet joint. Its main characteristic is the limitation of rotation to 5 degrees and tilt to 12 degrees. The function also consists of limiting the mobility of the spine, which helps maintain the balance of the human body.

By structure

In this group, the classification of joints occurs depending on the number of bones that connect:

• A simple joint is a connection between two bones (interphalangeal bones).
• Complex – a connection of more than two bones (elbow). The characteristics of such a connection imply the presence of several simple bones, while the functions can be implemented separately from each other.
• Complex joint - or two-chamber, which contains cartilage that connects several simple joints (lower jaw, radioulnar). Cartilage can separate the joints either completely (disc shape) or partially (meniscus in the knee).
• Combined - combines isolated joints that are placed independently of each other.

According to the shape of the surfaces

The shapes of the joints and the ends of the bones have different shapes geometric shapes(cylinder, ellipse, ball). Depending on this, movements are carried out around one, two, or three axes. There is also a direct relationship between the type of rotation and the shape of the surfaces. Further, a detailed classification of joints according to the shape of their surfaces:

• Cylindrical joint - the surface has the shape of a cylinder, rotates around one vertical axis (parallel to the axis of the connected bones and the vertical axis of the body). This species may have a rotational name.
• Block joint – cylinder-shaped (transverse) with one axis of rotation, but frontal plane, perpendicular to the connected bones. Characteristic movements are flexion and extension.
• Helical is a variation of the previous type, but the axes of rotation of this form are located at an angle other than 90 degrees, forming helical rotations.
• Ellipsoidal - the ends of the bones have the shape of an ellipse, one of them is oval, convex, the second is concave. Movements occur in the direction of two axes: bend-unbend, abduct-addite. The ligaments are perpendicular to the axes of rotation.
• Condylar is a type of ellipsoidal. The main characteristic is the condyle (a rounded process on one of the bones), the second bone is in the shape of a depression, and can differ significantly in size from each other. The main axis of rotation is represented by the frontal one. The main difference from the block-shaped one is the strong difference in the size of the surfaces, from the ellipsoidal one - the number of heads of connecting bones. This type has two condyles, which can be located either in the same capsule (similar to a cylinder, similar in function to the trochlear one) or in different capsules (similar to the ellipsoidal one).

• Saddle-shaped - formed by connecting two surfaces as if “sitting” on each other. One bone moves lengthwise, while the second moves across. Anatomy involves rotation around perpendicular axes: flexion-extension and abduction-adduction.
• Ball-and-socket joint - the surfaces are shaped like balls (one convex, the other concave), due to which people can make circular movements. Basically, rotation occurs along three perpendicular axes, the intersection point being the center of the head. The peculiarity is a very small number of ligaments, which does not interfere with circular rotations.
• Cup-shaped - the anatomical appearance involves a deep depression of one bone that covers most of the area of ​​the head of the second surface. As a result, there is less free mobility compared to the spherical one. Necessary for greater joint stability.
• Flat joint - flat ends of bones of approximately the same size, interaction along three axes, the main characteristic is a small range of motion and surrounded by ligaments.
• Tight (amphiarthrosis) - consists of bones of different sizes and shapes that are closely connected to each other. Anatomy: inactive, surfaces are represented by tight capsules, non-elastic short ligaments.

By nature of movement

In view of their physiological characteristics joints perform many movements along their axes. In total, there are three types in this group:

• Uniaxial - which rotate around one axis.
• Biaxial - rotation around two axes.
• Multi-axis - mainly around three axes.

Axis classification	Species	Examples
Uniaxial	Cylindrical	Atlanto-axial median
	Block-shaped	Interphalangeal joints of the fingers
	Helical	Humeral-ulnar
Biaxial	Ellipsoidal	Radiocarpal
	Condylar	Knee
	Saddle	Carpometacarpal joint thumb
Multi-axis	Globular	Brachial
	Cup-shaped	Hip
	Flat	Intervertebral discs
	Tight	Sacroiliac

In addition, there are also different types of movements in the joints:

• Flexion and extension.
• Rotation in and out.
• Abduction and adduction.
• Circular movements (surfaces move between axes, the end of the bone draws a circle, and the entire surface draws the shape of a cone).
• Sliding movements.
• Removal from one another (for example, peripheral joints, distance of fingers).

The degree of mobility depends on the difference in the size of the surfaces: than larger area one bone over another, the greater the range of motion. Ligaments and muscles can also inhibit range of motion. Their presence in each type is determined by the need to increase or decrease the range of motion of a certain part of the body.

Anatomy Tour Video

In the next video you can visually study the anatomy and see how the joints on the skeleton work.

The basis of the structure of a living organism is the skeleton, which includes movable joints, as well as bone and cartilage tissue. Human joints are important and necessary in order to walk and perform complex and coordinated movements in everyday work and professional activities. Arthrology is a complex science that studies all types of anastomoses with bones, a brief general explanation of which is mandatory for everyone.

Types, their anatomy and structure

A good example of studying the structure of bone anastomoses in the human body is the synovial joint. Clinical anatomy everything divides a person structural components into 2 types:

• Main elements:
  • articular surfaces - areas on the bones with which they come into contact (head and socket);
  • articular cartilage - protects against destruction due to friction;
  • capsule - is a protection, responsible for the production of synovium;
  • cavity - a gap between surfaces filled with liquid;
  • synovium - softens bone friction, nourishes cartilage, supporting metabolism.
• Supporting education:
  • cartilaginous disc - a plate that divides the cavity into two halves.
  • menisci - play the role of a shock absorber, located in the knee;
  • labrum - a border of cartilage around the glenoid cavity;
  • ligamentous connective apparatus - controls movements;
  • large and minor muscles.

The joints and ligaments of the limbs have received the most complete development, since they take on the basic functional abilities of a person in life and adaptation in society. During the process of evolution, the human hand was formed from the forelimb of mammals.

Functions and tasks

The joints provide shock absorption during motor activity person.

Different types human joints, their diverse anatomical design are of fundamental importance for a number of functional duties performed bone joints. All actions are divided into performing functions such as:

• The combination of bones, teeth and cartilage with each other makes them a strong shock absorber of movement.
• Preventing bone destruction.
• Performing axial movements, including:
  • frontal - flexion, extension;
  • sagittal - adduction, abduction;
  • vertical - supination (outward movement), pronation (inward);
  • circular movements - moving the stroke from axis to axis.
• Physical activity of a person, which ensures the correct structure of the joint.
• Maintaining the position of the skeleton.
• Influence on the growth and development of the body.

Classification, its principles

There are many compounds in the body, each has its own characteristics and performs specific functions. Most convenient in clinical practice The classification of joints into types and types is considered, which is successfully depicted in the table. It did not include the continuous intercartilaginous connections of the ribs, starting from the 6th to the 9th.

View	Characteristic	Type	Location Features
Fibrous	Connective tissue with collagen	Suture	Skull sutures
		Syndesmoses	Connects the radius and ulna of the forearm
		Nail-shaped	Teeth
Cartilaginous	The structure contains hyaline cartilage or disc	Synchondrosis	Joint of rib and manubrium of sternum
		Symphyseal or semi-joints	Pubic symphysis, intervertebral joints
Synovial	The joint connects the cavity, capsule, accessory ligaments, synovial fluid, bursa, tendon sheaths	Flat (sliding)	Sacroiliac
		Block-shaped	Elbow, knee, humeroulnar (helical joint)
		Ball	Sternocostal (cup-shaped)
		Hinged (cylindrical joint)	Connects the tooth epistotheus and atlas
		Condylar	Metacarpophalangeal fingers
		Saddle	Metacarpal thumb
		Elliptical	Radiocarpal

It should be noted separately that the combined type includes the joint of the rib head and the costovertebral joints. In the latter, the tubercle of the rib connects to the transverse process of the vertebra and makes it not very mobile.

Connection types

Joints are also divided according to the following criteria:

Joints can be classified according to the degree of mobility.

• Mobility:
  • synarthrosis - immovable;
  • amphiarthrosis - inactive;
  • diarthrosis - mobile.
• Axes of motion:
  • uniaxial joints;
  • biaxial;
  • triaxial.
• Biomechanical properties:
  • simple;
  • difficult;
  • complex.

Major joints in the human body

Hip

The articulation connects the femur to the pelvic bone.

Connects the parts of the pelvis with the head femur which are covered with cartilage and synovial membrane. Ball and socket joint lower limbs. Axes of movement - frontal, sagittal, vertical, circular rotation. The articular capsule is attached in such a way that the acetabular lip and femoral neck are located in the articular cavity. The connecting component element is represented by the ligament of the femoral head, pubofemoral, iliofemoral, ischiofemoral and circular zone.

Knee design diagram

Complex, condylar, most large joint on the limbs of the lower girdle it is arranged with the participation of the patella, the proximal edge of the tibia and the distal edge -. The anatomical ligaments of the knee joint are represented by three groups:

• Lateral - collateral tibial and tibial.
• Extracapsular (posterior) - patellar ligament, arcuate, supporting lateral-medial, popliteal.
• Intracapsular - transverse patellar ligament and cruciform.

Provides rotation and movement in the frontal axis. Has a number bursae, the number and size of which are individual. Folds of the synovial membrane accumulate adipose tissue. The surfaces of the joint are covered with a cartilaginous layer. Distinctive feature is the presence of outer and inner crescent-shaped parts of the cartilage, which are called menisci.

Ankle

The joint is more often injured in people actively involved in sports.

A movable joint in which the distal epiphyses (bottom) of the fibula and tibia are connected to the human foot, namely the talus. Block-shaped, involved in movements of the frontal and sagittal axes. The ligaments are represented by two groups: the lateral, which includes the talofibular and calcaneofibular ligaments, and the medial, or deltoid ligament. - the main area of ​​injury in athletes who move continuously.

Saddle

A type of synovial anastomosis, reminiscent of a rider on a horse - consistent with the name. Another bone is mounted on a bone similar in shape to a saddle. They are flexible compared to others. A striking example The joint that the human musculoskeletal system has is the metacarpal joint of the thumb. Here the saddle is the trapezium bone, and the 1st metacarpal bone. The opposable thumb on the upper extremities is a distinctive feature of humans, which sets them apart from the animal world, and thanks to which it is possible to perform work, including mastering new professions.

Paired elbow

Complex mobile articulation of the humerus with the radius and ulna, which consists of 3 joints surrounded by one capsule. Among them:

• brachioradial - a spherical joint, responsible for movements in two axes along with the elbow;
• humeroulnar - block-shaped, screw-shaped;
• proximal radioulnar - type 1 rotator joint.

The articulation has complex structure and has the most large size in the upper limbs.

The largest joint of the upper half of the body, which provides movement of the upper limbs and corresponds to their number. Anatomically, it is considered block-shaped with helical slides; lateral movements are impossible in it. Auxiliary elements represented by two collateral ligaments - radial and ulnar.

Globular

This includes the hip and shoulder joints of the bones (multi-axial structures), which have the greatest mobility. The name of this group was determined by an obligatory bone element resembling a ball: in the 1st example it is the head of the humerus, in the 2nd example it is the head of the femur. The general structural elements are represented by a spherical head at the end of one bone and a cup-shaped depression on the second. The shoulder joint has the greatest range of free movement in the skeleton; it is simple in structure, while the hip joint is less mobile, but stronger and more resilient.

Block-shaped

Types of joints that are classified as synovial. This includes the knee, elbow, ankle and less complex departments with good mobility - interphalangeal joints arms and legs. These joints, to the extent of their characteristics, are endowed with less force and hold a small mass, which is standard for their structure - small ligaments, hyaline cartilage, a capsule with a synovial membrane.

Elliptical

The wrist joint is of the ellipsoidal type.

The type of joint, also known as planar, is formed by bones with an almost smooth surface. In the joint space, the synovium, which is produced by the membrane, constantly functions. These moving joints contribute to limited range of motion in all directions. Representatives of the group are the intervertebral, carpal, and carpometacarpal joints in the human body.

Condylar

A separate subspecies of the ellipsoid class. It is considered a transitional type from block-shaped. A distinctive feature from the 1st is the discrepancy in the shape and size of the connecting surfaces, from the ellipsoidal one - the number of heads of the structure. There are two examples of such joints in the body - the temporomandibular and the knee, the latter moves around 2 axes.

Common diseases, their causes and symptoms

Diagnosis of joint diseases

Based on the following methods and techniques:

Goniometry allows you to determine how much a person can move a joint.

• Complaints.
• History of the disease.
• General examination, palpation.
• Goniometry is a characteristic of the free range of motion.
• Mandatory laboratory tests:
  • general blood test;
  • blood biochemistry, especially important C-reactive protein, erythrocyte sedimentation reaction, antinuclear antibodies, uric acid;
  • General urine test.
• Radiation research methods:
  • X-ray;
  • arthrography;
• Radionuclide.

Treatment of ailments

Therapy is effective only if the diagnosis is correct and if the diagnosis is not late. The table of main diseases highlights the cause that should be treated. When there are foci of infection, antibiotics are prescribed. At autoimmune process use immunosuppressants - monoclonal antibodies, corticosteroids, cytostatics. Degenerative conditions are corrected with chondroprotectors. Take nonsteroidal anti-inflammatory drugs that affect calcium levels and bone strength. Rehabilitation is provided physical therapy and physiotherapy. Surgical treatment applied after exhaustion conservative methods, but it does not guarantee complete blocking of any pathological process.

The human skeleton consists of more than 200 bones. Half of them are connected to each other through joints. Thus, joints are movable bone connections that unite the skeleton into a single whole. They are covered with cartilage tissue and have cavities (cracks) between the bones that make up them.

The main function of joints is to ensure that bones slide relative to each other during movements. In addition, they help maintain the position of the human body in space. The structure of joints has many common characteristic features: their heads are covered with connective tissue, which is lined from the inside with a mucous membrane that secretes viscous synovial fluid.

So, all joints consist of the following components:

Articular surfaces of connecting bones;
joint capsule (surrounds the ends of the bones that make up the joint);
articular cavity (located inside the capsule between the bones);
synovial membrane filled with synovial fluid, which plays the role of a kind of lubricant and promotes free movement of the articular ends
The knee joint includes a meniscus (cartilaginous formation).

The main reasons for the differences in the structure of the joints located in different parts bodies are anatomical features necessary to perform certain movements (flexion-extension, adduction-abduction, pronation-supination, rotation), as well as for the correct distribution of weight and load during movement.

General characteristics of fabrics

All joints of the human body, with the exception of a few, have a similar structure. They include a certain set of fabrics, each of which performs its own function, but at the same time the constituent elements may have different shapes, sizes and others specific characteristics. There are 5 main types of tissues, which are present to varying degrees in all types of joints.

1. The joint capsule is a fibrous layer that completely envelops the joint, maintaining its integrity under heavy loads. This layer is tightly adjacent to the bones, which gives the entire structure increased stability and prevents excessive displacement of joint fragments.
2. Cartilage is a special dense and at the same time elastic tissue. It consists of chondrocytes, as well as an intercellular substance called the matrix. This tissue covers the ends of bones, which are constituent elements joint Main functions cartilage tissue are protecting bones from damage during physical activity and reducing the intensity of their friction. Without cartilage tissue, bones would grind against each other due to friction during movement.
3. Ligaments are special strong connective tissue that connects bones and organs. Ligaments serve as the main strengthening element of the joint and at the same time perform a restrictive function, as they restrain the amplitude of movement of the bones included in the joint.
4. Synovial layer. This fabric has the appearance of a bag lining the entire inner surface joint, and produces a special intra-articular fluid, which facilitates the sliding of individual elements of the joint during their movement. It is worth noting that the fluid secreted by the synovium is the only means of nourishing the joint, since there are no blood vessels inside it.
5. Menisci are elements of the joint, represented by particularly hard cartilage, which are close in structure to bone tissue. In the knee joints there are 2 menisci in the shape of a crescent. Menisci allow better distribution of body weight and prevent premature wear of the cartilage tissue and bones of the joint.

Each of the articular tissues has its own characteristics of functioning in the joints different types. An important fact is that the structure and functional abilities of different joints are not the same.

In order to understand what exactly ensures the mobility of the human body, it is worth considering how each type of joint is designed.

The structure of the spinal column

The spine can hardly be called a joint in the literal sense of the word, since the spinal column is a complex osteochondral structure containing bone elements(vertebrae) and intervertebral discs. Each vertebra has processes. The articular processes form intervertebral (facet) joints, and ligaments and muscles that move the vertebrae are attached to the transverse and spinous joints.

Explained by the need to maintain the body in vertical position and at the same time provide motor ability to the whole body. The structure of the human spinal column is unique in many ways, which is associated with the peculiarities of upright walking. In addition, the structure of the spinal column is determined by the need to protect the spinal cord from various kinds injuries Violations of the integrity of the spinal column often lead to the most severe consequences up to immobilization of limbs and death.

Considering the structure of the spine, it can be noted that it has a curved S-shape, which gives it greater stability, flexibility, elasticity and helps alleviate pressure on its elements during running and other physical activity. This structure of the spine allows you to maintain an ideal balance of the center of gravity when moving in a vertical position.
In total, the spinal column contains 24 vertebrae, connected to each other by intervertebral discs that ensure their mobility. A number of departments can be distinguished, including a certain number of vertebrae:

1. Cervical region - 7 vertebrae.
2. Thoracic region - 12 vertebrae.
3. Lumbar region - 5 vertebrae.
4. The sacrum is 5 vertebrae fused together.
5. Coccyx.

Of great interest are the intervertebral discs, which serve as a shock absorber between adjacent vertebrae. Intervertebral discs are complemented by ligaments that connect individual bone elements to each other, giving strength to the entire structure. The integrity of the spinal column is also ensured by the longitudinal tendons and muscles of the back.

All vertebrae have openings through which the spinal cord passes. Facet joints prevent the bony structures of the spinal column from pinching the nerves that leave the spine.

Structure of the knee joint

The knee joints are the largest movable structures of the human musculoskeletal system. The anatomy of the knee joint has its own characteristics. The size of this connection is largely due to the need to support body weight during movement. The human knee joint can support up to 300 kg. Consideration of its structure must begin with the identification of its constituent parts. The following elements involved in the formation of the knee joint can be distinguished:

• lateral femoral condyle;
• medial femoral condyle;
• superior articular surfaces of the tibia;
• patella;
• quadriceps tendons;
• patellar ligament;
• hyaline cartilage;
• joint capsule containing synovial membrane;
• lateral tibial and fibular ligaments;
• posterior and anterior transverse ligaments;
• internal and external falciform menisci.

It is worth immediately noting that the ligamentous apparatus of the knee is extremely strong and literally envelops the entire structure of the joint. This structure gives the entire structure additional strength, which makes the knee joint very stable.
The main movements of the knee joint are flexion and extension, but there is also a slight ability to move the lower leg in and out, which helps avoid injury when turning the leg unsuccessfully.

The structure of the knee joint is real natural miracle. Throughout life, this joint bears the maximum load, but if a person leads correct image life, the articulation is preserved perfectly even in old age.

The structure of the shoulder joint

Unlike the knee joint, the shoulder joint has a less massive appearance, which is explained by the lack of need to support the weight of the entire body. However, the shoulder joint has its own characteristics that allow you to avoid injury to the bones when lifting and carrying various weights. Despite its modest size, it is very durable and at the same time provides a significant range of motion. The joint is arranged in a rather complex way, which is explained by the need to move the hand in all directions. The shoulder joint includes the following elements:

• humerus;
• humeral process of the scapula;
• labrum;
• intertubercular synovial membrane;
• tendon of the long head of the biceps muscle.

Detailed structure of the shoulder joint of the musculoskeletal system of a man

The shoulder joint has a spherical shape and is completely enveloped in dense fibrous tissue, forming a joint capsule, which is attached to outside edges of the glenoid cavity of the scapula on one side, and on the other side - to anatomical neck bones.

The joint capsule is reinforced on the outside with ligaments, which provides it with additional strength while maintaining mobility. The head of the humerus is attached to the glenoid cavity with the help of muscles and internal ligaments. In the upper part of the brachial process there is an intertubercular synovial membrane that produces intra-articular fluid.

Elbow joint and its structure

The elbow joint is in many ways similar, but there are still some significant differences. The anatomy of the elbow joint is explained by the need for not only flexion-extension, but also rotational movements of the radius and, accordingly, the wrist. Considering the structure of the elbow joint, we can immediately note that its functioning is ensured by 3 articular elements at once, each of which plays a specific role.

1. Shoulder-ulnar joint. This connection is responsible for ensuring the process of flexion and extension.
2. Brachioradial joint. This joint promotes flexion, extension and rotation.
3. Proximal radioulnar joint. This joint is responsible exclusively for rotational movements, supination and pronation.

All these joints are assembled into one articular capsule, which is why the entire structure functions as a screw-shaped one, that is, it allows not only flexion-extension movements, but also movements around the frontal axis. The joints are connected to each other by ligaments and tendons located inside the joint.

The cavity of the elbow joint is conventionally divided into two chambers: anterior and posterior. At the attachment points of the tendons of the muscles of the shoulder and elbow joint there are mucous bags that secrete intra-articular fluid. Innervation of the elbow joint occurs through the musculocutaneous, ulnar, median and radial nerve endings.

Blood supply to the tissues of this area is achieved due to the radial, brachial and ulnar arteries passing nearby.

Disease of the wrist element

The wrist joint is a rather complex joint of bones. It is worth immediately noting that many anatomists believe that only the spine has a more complex structure of bone connection than the wrist joint. In there is a connection of such bones as the scaphoid, triquetrum and lunate. In addition, this joint contains the connection of the carpal bones, including the metacarpals, capitate, hamate, triquetrum, large and small trapezius bones.
In this joint, the bones do not always have direct contact, but still a powerful ligamentous apparatus binds them together, forming a hand with increased functionality. Given the way the bones are connected, the wrist joint can perform movements aimed at flexion and extension, as well as adduction and abduction, but the movements are sharply limited and in most people their amplitude does not exceed 45 degrees.

The wrist joint capsule is attached top part to the triangular cartilage of the radial joint, while the lower part articulates with the lower row of carpal bones. On the palm side there are synovial membranes through which the main tendons pass, responsible for flexing the fingers, which are arranged in four layers. The tendons responsible for extending the fingers are attached to back side wrist joint in 2 layers. The blood supply to the joint from the palm is provided by the ulnar and radial veins, while the dorsal surface is supplied by the dorsal radial artery. This connection of bones is innervated by the median and ulnar nerves.

Ankle device

The ankle joint is a trochlear joint of bones formed by surfaces distal ends of the fibula and tibia in combination with the articular surface talus. All bone joints in the ankle joint are additionally strengthened by ligaments and tendons. This is due to the need to support the weight of the entire body while maintaining maximum mobility of the limb.
Connection of large and small tibia forms a fork that covers side surfaces talus. All surfaces of the bones that form the joint are covered with hyaline cartilage. The joint is enclosed in joint capsule, reinforced with a strong ligament mesh. The connection of the bones in the ankle joint allows you to maintain an amplitude of motion from 50 to 70 degrees, and in rare cases up to 90 degrees. TO ankle joint tendons responsible for flexion and extension of the fingers are attached. Blood supply is provided by the posterior and anterior tibial arteries.

GENERAL INFORMATION

Arthrology is a branch of anatomy that studies the joints of bones. According to development, structure and function, all bone joints can be divided into 2 large groups: continuous and intermittent. Continuous connections (synarthroses) are formed various types connective tissue. Intermittent joints (diarthrosis) are characterized by the presence of a cavity between the articulating surfaces of bones.

Depending on the type of tissue connecting the bones, three types of continuous connections are distinguished.

1. Syndesmosis, syndesmosis, is a type of continuous connection of bones through connective tissue. Syndesmoses include ligaments, interosseous membranes, sutures, fontanelles, and gomphosis. Fibrous ligaments, ligamenta, are fibrous bundles of connective tissue. Between the vertebral arches, the ligaments consist of elastic connective tissue (synelastosis), these are the yellow ligaments, ligament flava.

Interosseous membranes, membrana interossea, are connective tissue that fills large spaces between bones, for example, between the bones of the forearm and lower leg.

Sutures, suturae, are connective tissue that takes on the character of a thin layer between the bones of the skull.

Based on the shape of the connecting bone edges, the following sutures are distinguished:

A) serrated, sutura serrata, between the frontal and parietal bones, parietal and occipital bones of the skull.

B) scaly, sutura squamosa, between the edges of the temporal and parietal bones.

B) flat, sutura plana, between the bones of the facial skull.

Fontana, fonticuli, are non-ossified connective tissue areas of the cranial vault of a newborn.

Impaction, gomfosis, is the connection of a tooth with the bone tissue of the dental alveolus.

2.Cartilaginous connections, synchondrosis, synchondrosis, are continuous connections of bones through cartilage tissue. Synchondrosis can be temporary or permanent.

Temporary synchondrosis includes epiphyseal cartilages connecting the diaphysis and epiphyses tubular bones; cartilage between the sacral vertebrae. Temporary synchondroses persist in childhood and are then replaced by a bone connection - synostosis.

Permanent synchondrosis is present between the first rib and the manubrium of the sternum. If a narrow gap is formed in the center of the synchondrosis, which does not have the character of an articular cavity with articular surfaces and capsule, then such a connection becomes transitional from continuous to discontinuous and is called a symphysis, symphysis, for example, the pubic symphysis, symphysis pubica.

3. Bone joints, synostoses, synostosis, are formed as a result of the replacement of temporary cartilage with bone tissue or at the site of syndesmosis, for example, during ossification of the sutures between the bones of the skull in old age.

Intermittent, or synovial, connections. These include joints, articulatio. These connections have a more complex structure and, unlike sedentary or completely motionless continuous connections, make possible various movements of parts of the human body.

A joint, articulatio, is an organ in which basic and auxiliary elements are distinguished.

Main elements of the joint:

Articular surfaces, facies articularis, are located on the bones at the points of their articulation with each other. In most joints, one of the articulating surfaces is convex - the articular head, and the other is concave - the articular cavity.

Articular cartilage, cartilago articularis, covers the articular surfaces. Most articular surfaces are covered with hyaline cartilage, and only some joints, such as the temporomandibular and sternoclavicular joints, have fibrocartilage.

Thanks to its elasticity, articular cartilage protects the ends of bones from damage during shocks and shocks.

The articular capsule, capsula articularis, surrounds the parts of the bones that articulate with each other and hermetically closes the joint. In the articular capsule there are: a) an outer fibrous membrane built from dense fibrous connective tissue; b) the internal synovial membrane, which produces intra-articular fluid - synovium.

The articular cavity, cavitas articularis, is a slit-like space between the articular surfaces, which contains synovium.

Synovia is a viscous fluid that is located in the joint cavity. Synovia moistens the articular surfaces, reducing friction during joint movements, provides nutrition to the articular cartilage and metabolism in the joint.

Auxiliary elements of the joint:

The articular disc, discus articularis, is a cartilaginous plate located between the articular surfaces and dividing the articular cavity into two chambers.

Articular menisci, menisci articularis, are curved cartilaginous plates located in the cavity of the knee joint between the condyles of the femur and tibia. Articular discs and menisci increase the contact area of ​​the articular surfaces and act as shock absorbers and also play a role in movement.

The labrum, labrum articulare, is a cartilaginous rim attached to the edge of the articular cavity and increases its area and, consequently, the contact area of ​​the articular surfaces.

Ligaments, ligamenta, form the ligamentous apparatus of the joint, apparatus ligamentosus. Ligaments strengthen the joint, inhibit movement, and can also guide movement.

There are: a) extracapsular ligaments, separated from the articular capsule by connective tissue; b) capsular ligaments woven into the joint capsule; c) intracapsular ligaments located in the joint cavity and covered with a synovial membrane.

Classification of joints

The joints of the human body are very diverse in their structure and function. Classification of joints by structure:

A simple joint, articulatio simplex, is formed by two bones, for example the interphalangeal joints.

A complex joint, articulatio composita, is formed by 3 or more bones, for example the elbow joint, ankle joint.

A complex joint, articulatio complexa, is a joint in which there is a disc or menisci, for example the knee joint, sternoclavicular joint.

A combined joint, articulatio combinata, is a combination of several joints isolated from each other, but functioning together, for example, the temporomandibular joints, the proximal and distal radioulnar joints.

Based on the shape of the articular surfaces, joints are classified as spherical, cup-shaped, flat, ellipsoidal, saddle-shaped, condylar, trochlear, and rotational (cylindrical).

Movements in the joints are possible around the frontal, sagittal and vertical axes. 1) Around the frontal axis, movements are defined as flexion, flexio, and extension, extensio. 2) Around the sagittal axis – abduction, abductio, and adduction, adductio. 3) Movement around the vertical axis is called rotation, rotatio; a distinction is made between outward rotation - supination, supinatio, and inward rotation - pronation, pronatio. Circumduction, circumductio, is a circular movement, a transition from one axis to another. Based on the number of axes of motion, joints are classified into uniaxial, biaxial and multiaxial joints. Ball and socket joints are multiaxial. A typical spherical joint is the shoulder joint, movements in which are possible around 3 axes - frontal (flexion and extension), sagittal (abduction and adduction) and vertical (outward and inward rotation). The hip joint has a cup-shaped shape - it differs from the spherical joint in its deeper articular cavity. In flat joints, movements are sliding in different directions. Ellipsoidal, condylar and saddle joints have 2 axes of movement: flexion and extension occur around the frontal axis, and adduction and abduction occur around the sagittal axis. Block and rotation joints have one axis of rotation. In the trochlear joint, movements occur around the frontal axis - flexion and extension. In a cylindrical joint, movement occurs around a vertical axis - rotation.

Based on their functional characteristics, combined joints are distinguished, articulations combinatae; - these are 2 or more joints that are anatomically separate (that is, have separate capsules), but participate in movements together. For example, two temporomandibular joints, the proximal radioulnar joint and the distal radioulnar joint.

Classification of joints by form and function

Single-spinous joints

Double joints

Condylar, art. condylaris	Frontal, sagittal		Atlanto-occipital joints, art. atlantooccipitalis
Saddle-shaped, art. sellaris	Frontal, sagittal	Flexion, flexio, extension, extension, abduction, abduction, adduction, adductio	Carpometacarpal joint of the thumb, art. Carpometacarpea pollicis
Elliptical, art. ellipsoidea	Frontal, sagittal	Flexion, flexio, extension, extension, abduction, abduction, adduction, adductio	Wrist joint, art. radio-carpea

Triaxial (multi-axial) joints

Globular, art. spheroidea		Flexion, flexio, extension, extension, abduction, abduction, adduction, adductio	Shoulder joint, art. humeri
Flat, art. plana	Frontal, sagittal, vertical	Flexion, flexio, extension, extension, abduction, abduction, adduction, adductio	Facet joints, art. zygapophysialis
Cup-shaped, art. cotylica	Frontal, sagittal, vertical	Flexion, flexio, extension, extension, abduction, abduction, adduction, adductio	Hip joint, art. coxae

Chest joints

Synovial joints of the skull

Joints of the upper limb

Joints of the lower limb

Joints or synovial joints (articulations synoviales) are presented in the form of discontinuous connections of bones. They are among the most common types of articulation of human bones and are necessary to create all the necessary conditions for high mobility of the body. A simple joint (articulation simplex) is such if two bones were involved in its formation. A complex joint (articulation composita) is such if it is formed from three or more bones.

Each joint consists of mandatory structural elements and auxiliary formations. Basic elements allow joints to relate specifically to a number of joints. These include articular cartilage and surfaces, joint capsules and cavities. Accessory structures allow joints to have certain functional and structural differences.

Articular cartilage (cartilage articulares) consists of hyaline cartilage, but sometimes it can be constructed of fibrocartilage. It is necessary to cover bones that articulate and face each other. One surface of such a joint is fused with the surface of the bone, and the second part is freely located in the joint.

The articular capsule (capsula articularis) is presented in the form of a closed case and is necessary for the articulation of bones facing each other. It consists of fibrous connective tissue and has two layers - two membranes. The outer membrane also consists of fibrous tissue and is intended to perform a mechanical role. Inside, the first membrane passes into the second - the synovial membrane. Here it forms synovial folds (stratum synoviale), secretes synovium or synovial fluid into the joint, which nourishes the articular cartilage itself, as well as the surfaces of the bones, plays the role of a shock absorber and significantly changes the mobility of the joint. All this is ensured by the viscosity of the synovial fluid (synovia). Moreover, it is precisely due to the synovial folds and villi (vilii synoviales), which face the articular cavity, that the working surface of the membrane increases significantly.

The articular cavity (cavitas articularis) is a narrow closed gap, which is limited by articulating bones and a fluid-filled capsule. This cavity does not have the ability to communicate with the atmosphere.

The auxiliary parts and formations of the joints are quite diverse. These include ligaments, articular discs, menisci, and labrums. Each of the above entities should be described in more detail.

Joint ligaments (ligamenta) are presented in the form of bundles of dense connective fibrous tissue. They are necessary to strengthen the joint capsule and limit the guiding movements of bones in the joints. There are capsular, extracapsular ligaments and intracapsular ligaments. The first type of ligaments (capsularia) is located in the thickness of the capsule itself, namely between the fibrous and synovial membrane. Extracapsular ligaments are located on the outside of the composite capsule. They are harmoniously woven into the outer part of the fibrous layer. And the intracapsular ligaments are located precisely inside the joint, but are separated from its cavity by the synovial membrane. In general, almost all joints in our body have such ligaments.

Articular discs (disci articulares) are layers of fibrous or hyaline cartilage that are wedged between the articular surfaces. They are attached to the joint capsule and divide it into two floors. Thus, the discs increase the conformity of surfaces, volume and variety of movements. Therefore, the articular discs play the role of shock absorbers and significantly reduce shocks and shocks that occur during movement.

Articular menisci (menisci articulares) are presented in the form of crescent-shaped formations of fibrous cartilage. They are necessary to absorb a variety of movements. For example, in every knee joint There are two menisci, which are attached to the capsule located to the tibia, and the other sharper end is freely located in the joint cavity.

The labrum (labra articularia) is a dense formation of fibrous connective tissue. It is located at the edge of the glenoid cavity and is necessary to deepen it and increase the conformity of the surfaces. The labrum goes directly into the cavity of the joint itself.

Joints can also vary in shape and degree of mobility. According to their shape, we can distinguish spherical or cup-shaped joints, flat, ellipsoidal and saddle-shaped, ovoid and cylindrical, as well as trochlear and condylar joints.

It is important to note that the nature of possible movements in the joint depends on the shape. For example, spherical and flat joints have a generatrix in the form of a segment of a circle, so they allow movement around three axes perpendicular to each other (frontal, sagittal and vertical). Therefore, the shoulder joint, which has spherical shape(articulations spheroideae), allows for flexion and extension relative to the frontal axis, as well as combining this action with the sagittal axis or abducting and adducting the action relative to the frontal plane. Also around the frontal axis, rotation can be carried out relative to the horizontal axis with turns inward or outward. In flat joints, movements are quite limited, because the flat surface looks like a small segment of a circle with a large diameter. Ball-shaped joints allow you to perform actions with a fairly large amplitude of rotation, as well as with the addition of leading actions in a circle. In the latter case, the center of rotation will be the ball-and-socket joint, and the moving bone will describe the so-called cone surface.

Biaxial joints are those joints that can only move around two axes at the same time. These include wrist joints in the form of ellipsoid joints, as well as the carpometacarpal joint of the first finger of the hand in the form of a saddle joint.

TO uniaxial joints These include cylindrical (articulations trochoideae) and block-shaped (ginglymus) types of joints. In the first case, the movement occurs parallel to the axis of rotation. For example, the atlantoaxial median joint with a vertical axis of rotation, which passes through the second tooth cervical vertebra and proximal radioulnar joint. In the second case, the generatrix of the joint is knee or beveled relative to the axis of rotation. An example of this type of joint is the interphalangeal or ulnohumeral joint.

Condylar joints (articulations bicondylares) are slightly modified elliptical joints (articulations ellipsoideae).

In general, there are cases when movements can only be realized with simultaneous movement of adjacent joints. They are anatomically isolated but united common function. This combination should be taken into account when studying the structure of the human skeleton and when analyzing the structure of movements.