What are joints?
Anatomically, a joint is a movable connection of at least two bones. A distinction is made between genuine joints (diarthroses) and non-genuine joints (synarthroses). One speaks of a real joint when there is a gap between the ends of the bones - the so-called joint space - when the joint surfaces are covered by articular cartilage and there is a joint capsule around the joint. The non-genuine joints are cartilaginous bone joints or connective tissue bone joints. The most familiar cartilaginous bone joints are found, for example, in the rib cartilage but also in the intervertebral discs (fibrocartilage).
Which joints are there?
There are different types of joints. The best known are the ball joint, the ellipsoidal joint, the saddle joint and the cylindrical joint. As the name suggests, the ball and socket joint is recognised by the fact that a spherical joint head fits into the counterpart of the second bone, which is shaped like a shell. One also speaks of a triaxial joint, such as shoulder joint or hip joint.
The ellipsoidal joint is a biaxial joint. Here, the ball is elliptically shaped, like the wrist joint between the radius and the carpal bone, for example. Another biaxial joint is the saddle joint, which actually looks a bit like a saddle and can be moved around two spatial axes (e.g. between the carpal bone and the metacarpal bone).
Finally, the cylindrical joint is very reminiscent of a hinge, which is why it is also called a hinge joint (e.g. elbow joint). Another cylindrical joint is the mortise and tenon joint, which works a bit like the mortise and tenon hinge of a door - we find this in humans between the radius and the ulna.
Why do joints crack?
Many people know it and find it a bit scary: cracking joints. The reason for this is only half explained. It may be that the surfaces of the knuckles are not flat, and if these bumps rub against each other, it could crack. But it could also be small gas bubbles in the synovial fluid (synovia) that are responsible for the noise.
How do joints stay healthy?
Bones and joints have a hard life and really have to go along with everything a person wants. Walking, running, sitting, lying down. The knee joint and hip joint are subjected to the most stress, but so are the unreal joints, the intervertebral discs. Depending on the load, joints or the joint cartilage can wear out, limiting mobility or range of motion and causing pain, as in the case of arthrosis or Osteochondrosis. Of course, you can never completely rule out arthrosis or a herniated disc, but you can do a lot to ensure that your joints stay pain-free for as long as possible.
It is known that - especially in the case of arthrosis - you can also achieve something with a change in diet. It is also not advisable to expose oneself to extreme physical stress, such as running a marathon, when there is a certain amount of recognisable wear and tear on the joints. But in principle, movement is better than immobility, because movement produces synovial fluid, which of course is good for the hinges - the joints! - are good. Exercise can be gymnastics, moderate walking, cycling or swimming. And you can even move while sitting, if you have a chair or office chair that allows movement while sitting, such as an ergonomic chair from Aeris.
Joints can remain healthy and naturally pain-free for a very long time if they are treated with care and given regular, healthy, natural exercise.