Joints are called mobile joints of various bones. A characteristic difference from other forms of combining various elements in the structure of the skeleton of the human body is the presence of a certain cavity filled with liquid. Each joint consists of several parts:
- cartilaginous (hyaline, with the exception of the connection of the lower jaw with the temporal bone) surface;
- capsule;
- cavity;
- synovial fluid.
General concept of human joints
The thickness of the cartilaginous layer can be different: from very thin, about 0.2 mm, to quite thick - about 6 mm. This significant difference is determined by the workload on the joint. The greater the pressure and its mobility, the thicker the hyaline surface.
The classification of human joints implies their division into several independent groups defined by a similar sign. Conventionally, we can distinguish:
- by the number of surfaces - simple, complex, combined, complex;
- along the rotation axes - uniaxial, biaxial, multiaxial;
- in shape - cylindrical, block-shaped, helical, ellipsoidal, condylar, saddle-shaped, spherical, flat;
- by possible movement.
Variety of combinations
Various cartilaginous surfaces that work interconnected determine the simplicity or complexity of the joint structure. The classification of joints (anatomy table) allows them to be divided into simple, complex, combined, complex.
| Classification of the structure of joints | Characteristic | Name of joints |
| Simple | Formed by 2 bones | Interphalangeal |
| Difficult | Formed by 3 or more bones | Elbow |
| Integrated | Have an additional disk or meniscus | Knee |
| Combined | Work in pairs at the same time | Temporomandibular |
Simple - characterized by the presence of two cartilaginous surfaces, and they can be formed by two or more bones. As an example, the joints of the upper limb: phalanx and wrist. The first of them is formed by two bones. The second is more complex. One of the surfaces of the wrist joint has a base immediately of the three bones of the proximal carpal row.
Complex - are formed from three or more surfaces placed in one capsule. In fact, these are a few simple joints that can work both together and separately. For example, the elbow joint has as many as six surfaces. They form three independent compounds in one capsule.
Some joints, in addition to the main ones, have additional devices, such as discs or menisci. The classification of joints calls them complex. Disks divide the joint cavity into two parts, thereby forming a "number of storeys" of the joint. Menisci look like a crescent. Both devices ensure the conformity of the adjacent forms of cartilage in the joint bag relative to each other.
Classification of joints by structure distinguishes such a concept as combination. This means that two separate compounds, being independent, can work exclusively together. A typical example of such synergism is the right and left temporomandibular joints.
Possible rotation
Joint joints provide the nature, amplitude and trajectory of the human skeleton. Rotation occurs around biomechanical axes, of which there may be several. Among them, vertical, sagittal and transverse are distinguished. The classification of joints on this basis distinguishes several types.
- Uniaxial - have a single axis of rotation. For example, interphalangeal joints provide flexion and extension of the fingers, other movements are impossible.
- Biaxial - two axis of rotation. A typical example is the wrist joint.
- Triaxial - movement in all possible planes - the shoulder, hip joints.
Variety of shapes
The classification of joints by shape is quite extensive. Each compound has been evolutionarily adapted to reduce workload and increase labor.
- Cylindrical . It has a single axis of rotation - longitudinal. It is interesting that there are cylindrical joints with a fixed center around which the ring rotates (Atlant-Axis), and vice versa, as in the radiolactic joint.
- Block - a uniaxial joint. The name is directly determining its structure. One surface has a ridge shape, which is combined with the groove of the second cartilage, thus forming a castle (interphalangeal joints).
- Helical . One type of block connection. It has one axis and an additional helical displacement. An example is the elbow joint.
- Ellipsoid - rotates along two axes - vertical and sagittal. Movement in this joint provides flexion, extension, adduction and abduction (wrist joint).
- Condylar . Biaxial joint. Its shape is remarkable for a strongly convex cartilaginous surface on one side and flat on the other. The latter may show a slight indentation. The most striking example is the knee joint. The classification distinguishes other compounds of the condylar form. For example, the temporomandibular joint.
- Saddle-shaped . It is formed by two surfaces - curved and concave. An educated joint is able to move along two axes - the frontal and sagittal. A striking example is the phalanx-metacarpal connection of the thumb.
One of the most massive in the body is the hip joint. The classification calls it spherical. It has a characteristic shape. The movement is carried out in three possible axes. One of the varieties of a spherical shape is a cup-shaped joint. It has a smaller amplitude of possible movements.
Classification of bones and joints distinguishes their division into departments. For example, the belt of the lower or upper limbs, skull, spine. The latter consists of small bones - vertebrae. The joints between them are flat, inactive, but capable of movement along three axes.
Joint of the temporal bone and lower jaw
This joint is combined and complex. Movement occurs simultaneously on the right and left. Any axis is possible. This is ensured by the adaptation of the lower jaw for chewing and speaking. The joint cavity is divided in half by a cartilaginous fibrous disc, which is fused to the joint capsule.
Joints hurt?
Joints in the human body perform an important function - movement. When they are healthy, the amplitude of the action is not violated. Life without a feeling of pain and discomfort is much more pleasant than with them.
There are various diseases of the joints. The classification divides them into groups according to their specific symptoms, the complexity of the process, and the nature of the course (acute, subacute, chronic). Pathologically isolated:
- arthralgia (joint pain of a fixed or volatile nature);
- arthritis (inflammatory processes);
- arthrosis (degenerative irreversible changes);
- congenital diseases.
Arthritis
A large number of diseases affect the supporting apparatus, causing dysfunction of the joints. The classification of arthritis distinguishes infectious, non-infectious, traumatic and concomitant (with other diseases). A detailed list was approved in 1958 by the Congress of Rheumatologists.
Infectious arthritis, which make up an extensive group of diseases, are specific, which are caused by the damaging effect of known types of pathogens, for example, tubercle bacillus, or evolutionary. Joint diseases are especially distinguished by the authors: Sokolsky — Buyo, Ankylosing spondylitis, Still.
Non-infectious arthritis is also called dystrophic. They are found quite often, the etiology is the most diverse. Among the causes may be age-related changes, the negative impact of environmental factors (hypothermia, excessive stress), hormonal and metabolic disorders (gout, thyroid disease, hemophilia, etc.).
Traumatic arthritis develops with blunt injuries, wounds of joints. In addition, they can occur due to prolonged exposure to vibration.
A large number of arthritis accompany other diseases that are not associated with the musculoskeletal system. Chronic forms of psoriasis, systemic lupus erythematosus, dermatoses - all are able to involve joints in the process. In addition, arthritis causes leukemia, some lung diseases (sarcoidosis) and the nervous system. Lead intoxication also often provokes a degenerative process in the joints.
Arthralgia
Pain associated with joint function is called arthralgia. The nature of its manifestation may be superficial or deep, permanent or temporary, affecting one or several cartilage joints at once. The disease most often affects the largest joints in the human body: knee, ulnar, hip. Smaller ones are much less affected.
Arthralgia often becomes an accompanying symptom in various infectious diseases, especially those with febrile conditions. In the diagnosis, various examination methods are used with a mandatory history. Laboratory studies include counting the number of platelets in the blood, as well as other tests and samples.
Arthrosis
The classification of joints affected by arthrosis cannot be limited by their singularity or a specific group. In itself, this disease is quite serious, as it is associated with the destruction of cartilage. This leads to joint deformation. It is proved that a genetic predisposition, heredity, plays a significant role in the development of arthrosis. At risk for this disease are people whose professions are directly related to the constant load on the joints: hairdressers, athletes, drivers, etc. The reason may be long-term hormonal disorders in the body.
Congenital malformations of the joints
The severity of congenital malformations of the joints varies from mild to severe. There are many diseases of newborns. These include: arthrogryposis, pseudarthrosis of the lower leg, congenital dislocation of the thigh or patella, dysplasia of the hip joints, Marfan syndrome (autosomal disease).
Joint disease prevention
In recent years, diseases of the musculoskeletal system have become very young. If earlier the average age of patients was at the level of 55 years, now it is fixed at 40.
In order to avoid serious complications and to live a long life without restricting your movements, it is important to monitor general health and conduct timely prevention. It consists in controlling body weight, proper nutrition, eliminating bad habits and moderate physical activity.