Physiology of going from chest to head voice

Hi 1st post here! does any one know what actually happens when you go from chest to head voice and the opposite? is it just a change of resonance are or is there an actual changing of physical parts. i know we only have one set of vocal cords so that can't be exchanged for something else. thanks!
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welcome to these Forums, Singer. That is a very good question. Without getting to technical: it is both. The vocal muscle (https://en.wikipedia.org/wiki/Thyroarytenoid_muscle) changes also the shape of the vocal ligaments and makes them thinner as we sing in falsetto. This is a very complex procedure. To make it easy: the larynx can make our vocal ligaments like a string of a bass guitar as well as string of a regular guitar.
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