A joint is a relationship between body parts

Disclaimer : This information is not guaranteed to be accurate and I am not liable if you make any decisions or take any actions, in terms of medical treatment, health decisions, exercise, behavior or anything else based on the information presented.  I am not telling you any decisions to make even if I use terms like "you" but am using the word "you" as part of a writing style to simplify writing.  Any suggestions for what "you" should do are not for you personally to do but what someone might do as part of a exercise or nutrition program which might help some people's health and make other people's health worse.  You should not do any activity that will make your health worse even if "you" should do it according to the program described.  If the information is wrong and you believe it is true, act on it and it causes you problems, I am not responsible because I have warned you the information is not guaranteed to be accurate.

A joint is a relationship between, bones, cartilages, muscles, nerves, blood vessels, tendons and ligaments

When you flex your elbow your elbow joint is not rotating, your humerus is staying approximately still but your radius and ulna are rotating around an axis close to the proximal end of the radius and proximal end of the ulna

There is no single bone, cartilage, muscle, nerve, blood vessel, tendon or ligament called an elbow or an elbow joint but the elbow joint is a relationship between bones, cartilages, muscles, nerves, blood vessels, tendons and ligaments that enables movement of the radius and ulna relative to the humerus.  That is why the elbow joint does not technically rotate because part of the elbow joint stays still and the other part rotates.  The elbow joint instead flexex or extends, bends or straightens as two bones rotate and the other remaining bone stays still.

It is sometimes more ambigous than someone thinks to say an action occurs at a joint or what a joint is composed of

One might ask are 100% of each of the bones, cartilages, muscles, nerves, tendons and ligaments that make up a joint part of the joint or only a fractional portion of each bone, cartilage, muscle, nerve, blood vessel, tendon or ligament.

For example if the elbow joint is made of the humerus, radius and ulna then one could argue that when someone is said to pronate or supinate their wrist they are pronating or supinating their elbow.  Because when they pronate or supinate their wrist the distal end of the radius a bone in their elbow rotates around the axis of their ulna another bone in their elbow.  But, the proximal end of the radius which common people might call part of the elbow and not part of the wrist does not move as much as the distal end of the radius which common people do not usually call part of the elbow but call part of the wrist so one might say the pronation or supination occurs at the wrist.  Where does the elbow end and the wrist begin?  Is part of the elbow also part of the wrist or is there no overlap between the wrist and the elbow? If only the proximal part of the radius is part of the elbow but not the distal part of the radius near the wrist, then at what point does the radius stop being part of the elbow?  If the entire radius is part of the elbow then it would be just as legitimate to call pronation of the wrist, pronation of the elbow.   If the entire radius is part of the elbow and also the entire radius and the nerves that go through the radius are part of the wrist then someone could experience pain in their wrist at the distal end of their radius at a location closer to their thumb than their humerus and call it elbow pain and be technically correct.

In the same way that a individual tree is a real thing but a forest is a social construction, bones, cartilage, muscles, nerves, tendons and ligaments are real things but joints are social constructions.

Copyright Carl Janssen 2022