下巴和TMJ(囓顎關節)息息相關，不論是講話或吃飯(speech or swallow)都離不開它，而現代人有此問題的也不佔少數。
The TMJ will be mbile only if the muscles that attach the lower jaw to the skull are elastic and not overly constricted. The most important means of enabling the lower jaw to drop dwon is the force of gracity, and we want to be able to take advantgae of that force.
有三塊肌肉是打開下巴: masseter and underlying medical pterygoid work to close the jaw, as does the temporalis.(這些肌肉一般處於過度工作的狀態，如果無法放鬆他們，則vocal , TMJ都會產生問題)
只需一塊肌肉去幫助重力來打開下巴: lateral pterygoid msucle，很有意思地是，它的位置近乎是和重力垂直的方向, across the cheek
古人常說的舌抵上顎，可能便是要把下巴放鬆，而且這是非常重要的，否則頸椎也必然會產生症狀。
練習: talking sloppy
Exaggerate far beyond any normal mode of speech but without forcing. Ask yourself for a loose floppy lowr jaw and a loose floppy tongue- so much so that you can hardly be understood. Saying or singing "blah.balh.balh? often achieves this sloppiness quite automatically. Real-life teelphone conversations can provide a good ooportunity to practice this loose-jawed speech. Important reminder: loose and sloppy speech does not mean a collapsed chest or slumping posture.
