Diarthrosis, Synovial Joint

Diarthrosis, Synovial Joint is a type of joint that allows free movement between bones. It is the most common type of joint in humans and plays a key role in maintaining mobility and flexibility of the body.

The articular ends of the bones, which are connected in diarthrosis, are covered with hyaline cartilage. This cartilage acts as a shock absorber, absorbing shock and providing a smooth surface for movement. The bones are connected to each other by a ligament, which forms a capsule surrounding the joint. This capsule serves to protect the joint from injury and impact.

The inner layer of the joint capsule is formed by a thin synovial membrane. This membrane produces synovial fluid, which lubricates and nourishes the joint. This fluid also plays an important role in lubricating and protecting joint surfaces from friction.

As mentioned, diarthrosis can vary in the type of bone connection and the type of movement it allows. There are several types of diarthrosis, including the pars plana, condylar, ball and socket, trochlear, and saddle joint. They differ in the shape of the articular surfaces and the type of movement they allow.

The hinge joint is one of the most famous types of diarthrosis. It consists of a spherical head, which is connected to a groove. This type of joint allows for a large range of motion, including rotation, flexion, and extension.

In conclusion, Diarthrosis, Synovial Joint is an important type of joint that allows free movement and flexibility of the body. It consists of articular surfaces, hyaline cartilage, ligaments and a synovial membrane that produces synovial fluid. Different types of diarthrosis allow for different types of movement, and they play an important role in our ability to move and function.

Diarthrosis (articular joints)

Diarthrosis or articular joints are a complex of anatomical structures located between the articular surfaces. Thanks to such connections, the bones of the body are able to move relative to each other, which is necessary for various movements and actions. In this context, the synovial joints play a major role.

Synovial type joints

They are also called synovial or free joints. A distinctive feature of such joints is that they are not fixed by “roots” or other tight structures that could limit the range of movement. Instead, the articular surfaces are recessed into one another. The bones are surrounded by periarticular connective tissue in the form of a capsule, or bag. It performs the function of shock absorption, while the edges of the surfaces remain sufficiently free. In the inner layer of this bursa there is a thin synovial membrane that moisturizes the joints - it produces and secretes synovial fluid. This type of joint is divided into: * *uniaxial* (with one active movement); * *multi-axis*.

Among multi-axial joints, the most common is the circulatory joint. These joints have two different movable elements (eg the humerus), making them multi-axis.

Types of joints:

> * Threaded Joints: Allow one joint to rotate around another at a certain angular distance. These are predominantly flat joints made from the same bone, an example is the wrist joint. They are characterized by a fixed connection of surfaces and very flexible fibers connecting them. For example, a hollow joint inside a double-cylinder joint determines the range of motion of the wrist. For this reason, such joints can only rotate. This type of joint requires very little tension, as well as to make the cartilage layers of cartilage thinner.*

The **Hingle-and-trochlear joint** connects bones as a single unit, such as the big toe and its finger bones, the human thumb and little finger, the metacarpal bones and the ankle bones. Here, the distal phalanx of the limb rotates around the block of bone of the large phalanx with a fixed proximal phalanx, to which the muscle bundles are attached. The atlantoaxial joint is similar to the hinge-trochlear joint - it connects the temporal bones of the skull with the first vertebra (Atlanta). This movement provides flexibility to the human neck when extending and rotating the head - this is possible due to

**Diarthrosis** are elements of the joint that ensure its functional mobility. Described by A.S. Zimnitsky 1837–1840. Consist of hyaline or fibrous zones. The first is constantly supported by cartilage or tissue forming a capsule. In some cases, diarthrosis plays a stabilizing role. For example, this happens with a trochlear joint. Due to a pathology similar to ankylosing spondylitis, the range of movements in the wrist joint and interphalangeal joints of the hand is sharply limited. When examined under a microscope, the joints reveal the presence of hyaline nodules, which explains the impairment of mobility, indicating the degree of impairment). If fibrous changes occur in the capsule of the radiocarpal joint, then its thickness increases greatly; it protrudes into the joint cavity. This leads to the development of subluxation of the wrist joint due to indirect injury or when working in a gentle mode (for example, “sedentary work”). Characteristic are nodules and thickening of the capsule. Other movement disorders (lack of range of motion) are also accompanied by the presence of nodules and focal changes in the joint capsule, clearly visible under a microscope.

Thus, the diagnosis of damage to the articular ends depends on a number of factors: 1) description of the configuration of the joint and its