We may say that a joint is a point where two or more things are connected. In this joint of the human body, it is the place where two bones connect. Joint means a junction or in other words, a strong connection that connects the bones, cartilage and together. Joint is necessary for all time movement in the body involving bones. Muscles generate force used to carry out movements through various joints. The ease and degree of movement at different joints vary with a lot of different factors. They can be classified based on two things.
Classification of Joints
A joint which does not allow any kind of movement is known as Synarthrosis. The suture of the skull and gomphosis connecting teeth to the skull are some examples of synarthrosis.
The slightly movable joint is called amphiarthrosis, which usually allows very little movement at one of the joints.
Examples of this amphiarthrosis are some of the intervertebral disks present in the spine and also pubic symphysis located in the hip and lower portion of the body.
These kinds of freely movable joints are known as diarthrosis joints. Diarthrosis is said to have the highest degree of moving of any kind of joint and also includes the elbow, the wrist, shoulder, and knee.
These joints, also classified based on the structure of the material present in the body, are as follows:-
A fibrous joint
This is the most usable and most common kind of joint, which is found between bones that move against each other. A synovial joint is called diarthrosis, joins cartilage or bones with a fibrous joint. These joints allow bones to rotate around each other and to slide past each other. The synovial joint has a joint cavity filled with fluid, together with muscles, ligaments, tendons, the capsule keeps the bones of the joint in place. This arrangement allows movements. The membrane that lines up the capsule produces oily synovial fluid and lubricates the joints, reducing friction and wear and tear.
Structural Features of Synovial Joints
These joints are explained by the presence of a joint cavity and their walls are formed by articular capsules. Synovial joints are more complex than the other types of joint and their structural components include
Joint cavity or capsules
Types of Synovial Joints
Synovial joints are also called diarthrosis joints and almost all the joints present in our body are synovial joints. There are almost six different kinds of synovial joint and mainly classified based on their shapes of the articulating surface of bones that form each other.
Plane joints are also known as gliding joints or arthrodial joints. Plane joints allow sliding and gliding movements that the articular surfaces of the bones are flat meaning they only allow movement to occur in uniaxial joints.
Plane joints present between ankle joints and carpals of the wrist that produce different types of movements are:-
Hinge joints are the types of joints with cylindrical projections, which hardly resemble the hinge of a door or a window. These are uniaxial joints with a single plane motion that permit extension.
The hinge joints are located in the elbow.
Pivot joints are known as a trochoid joint, rotary joint, in vertebrate anatomy, a freely movable joint that allows only rotational movement around a single axis. The moving bones rotate within a ring that is formed from an adjoining ligament and second bone.
Examples of pivot joints are the first and second bones of the neck which allows the head to move back and forth. Joint of the wrist, that allows the palm to move.