A present to get your head around- joint coupling.

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All,

A little Christmas present from me to you. Joint "coupling" is something we've discussed a number of times here. It seems that the concept of joint "coupling" is being applied not only to adjacent segments moving in the same direction, but even to non-adjacent segments moving in the same direction, I think Nester has expressed this idea in one of his papers. But consider this: if we have two segments travelling in the same direction, yet travelling at different velocities, then those two segments have to be moving away from one another or toward one another. Viz. How can this be considered as a "coupling"? Just an observation based on my 11 year old daughters physics homework.... surely two segments moving away from one another is an uncoupling?

As you drive your car, another car overtakes you and continues to accelerate away from you- In what way is this car coupled to yours? Now, let's hitch a ride... you breakdown in your car and someone offers to tow you home so they couple a rope twixt their car and yours... what happens when they travelling faster than you? Is this even possible with a physical connection? What happens when they are travelling slower than you?

Merry Christmas and Peace on Earth.

 

I had a little to much free time this am.

From Wikipedia, the free encyclopedia

Look up coupling in Wiktionary, the free dictionary.

Coupling is a connection or joint between two things.
Coupling may also refer to:

• Coupling (physics), when two systems are interacting with each other
  • Rotational–vibrational coupling, occurring when rotation frequency of an object is close to or identical to a natural internal vibration frequency
  • Angular momentum coupling, the combining of quantized angular momentum (e.g., the interaction between two nuclei in nuclear magnetic resonance)
  • Quantum coupling, when quantum states in one of the systems will cause an instantaneous change in all of the bound systems
• Coupling (computer programming), the degree to which each program module relies on each one of the other modules
• Coupling (electronics), the transfer of a signal from one medium or circuit block to another
• Coupling (genetics), a type of genetic linkage
• Coupling (piping), a short length of pipe or tube to connect two pipes or tubes together
• Coupling (probability), a proof technique in probability theory
• Railway coupling, a mechanism for connecting railway rolling stock
• Azo coupling, often called "coupling", an electrophilic substitution reaction
• Coupling reaction, reactions between hydrocarbon fragments in organic chemistry
• Hose coupling, a piece on the end of a hose to connect it to extra hoses or hose appliances
• Coupling track, a term in music recording for a B-side track
• Joint encoding, an audio compression technique in which the redundancy of information between audio channels is reduced; also commonly known as channel coupling or stereo coupling
• Mating or the act of sexual intercourse
• Coupling, the distance formed by the lumbar vertebrae of a horse's back.

For our purposes, in the foot, I think we are using the "Coupling (physics), when two systems are interacting with each other" definition. For example one system could be the tibia and talus and another system could be the calcaneus and rest of the foot. They are coupled in that some of the motions of one will tend to cause motion in the other. The classic mitered hinge concept would be a way to think of coupling here. It is interesting to think of the free body diagrams of how motion of one part will create forces on the other part to create motions in the second part. And that is what I believe is the importance of the idea of coupling. Understanding how the forces on anatomical structures are created.

Eric