What is a Joint?
A joint generally means a point where two or more things are connected together. In this scenario, it is the point where two bones intersect. Joint means an articulation or in other words, a strong connection that joins the bones, teeth, and cartilage together. It is necessary for all types of movement in the body involving bones. The force generated by muscles is used to carry out movement through various joints. The degree and ease of movement at different joints vary with a lot of different factors. They could be classified based on two different things.
Classification of Joints
A joint is classified based on functionality as to how much movement it allows:
- Immovable: A joint which permits no kind of movement is called as a synarthrosis. The sutures of the skull and also the gomphosis connecting teeth to that of the skull are some of the examples of synarthrosis.
- Slightly movable: An amphiarthrosis usually allows a very little amount of the movement at one of the joints. Examples of this amphiarthrosis include some of the intervertebral disks present in the spine and also the pubic symphysis present in the hips.
- Freely movable: The third class of functional joints is said to be freely moving kind of diarthrosis joints. Diarthrosis are said to have the highest range of the motion of any kind of joint and also includes the knee, elbow, shoulder and also the wrist.
Joints are also classified based on the structure of the material present in them.
- A fibrous joint is made up of tough collagen fibre, which does not allow any type of movement and also includes the sutures of the skull along with the syndesmosis holding together the ulna in addition to the radius of the forearm.
- Cartilaginous joints are said to be made up of bones that are joined together with the help of cartilage. Some examples include the joints present between the ribs and the costal cartilage and also the intervertebral discs present in the spine of the body.
- The most common kind of the joint, the synovial joint is said to be characterized by the presence of fluid-filled space between the smooth cartilage pads present at the ends of the articulating bones. Such an arrangement allows movement. The Synovial membrane that lines up the capsule produces oily synovial fluid and lubricates joints, reducing the friction and wear & tear.
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