Hi everyone! I couldnt find anything that answered this question, so here goes: Im doing osteology right now and I came across this phrase on Wikipedia:
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“Sesamoids act like pulleys, providing a smooth surface for tendons to slide over, increasing the tendon’s ability to transmit muscular forces.”
I think I kind of understand how pulleys work: You use less force over a longer distance, yet the amount of work is the same.
Im confused as to how this is applied on sesamoid bones. I understood they are “simply” embedded into our tendons. How exactly would they be creating a larger distance, as seen by the mechanism of pulleys? And how would that put less strain on the tendons?
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If I got it wrong please let me know! (Will flair this under physics since I believe my problem is understanding its biomechanics.) Thank you so much in advance!
In: Physics
The ability for pulleys to multiply force is when you chain them together in a “block and tackle” arrangement. That’s useful, but not the only reason to use pulleys and it’s not what those bones are doing.
The *other* reason to use pulleys is to reduce friction when a “cable” would otherwise rub on something, typically when it changes direction or has a long unsupported span. This doesn’t do the force multiplying thing but, by reducing friction, let’s more force get to the end of the “cable” where it’s needed. If I want 100N at the end of the cable, with good pulleys, I might only need to pull with 101N of force. With no pulleys I might need to pull with 150N to overcome
friction going around corners.
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