Im going to explain this quick and simple. Also I am not for training the jaw whatsoever because youll have a high risk of developing TMJ. So my advice as always would be to get relatively lean, improve posture and just start fucking saving money for jaw surgery or implants you coping lazy procrastinating fuck.
So your jaw is made up by different muscles. The main muscles are the masseter, temporalis and the medial/lateral pterygoid.
Your jaw muscles have different functions:
So how can you train these functions? You cant add external resistance so you will do isometrics for them. For the masseter you will train jaw elevation by doing a max effort isometric jaw clench, to train the temporalis you will train jaw depression by doing a max effort isometric jaw opening:
To train the medial and lateral pterygoid you will do a max effort jaw protraction and retraction. For protraction you will do a max effort isometric jaw push forward and for retraction you will do a max effort isometric jaw pull they also lateral excursion which you can do a max isometric jaw push to each side:
Now will this be effective??? Probably not i dont even know lol. But physiologically speaking its the only possible way. I am making this post to kinda shit on all the stupid retarded methods out there and show something that could potentially work. Do I recommend this? Hell no. Youll probably end up with TMJ. So just get lean and start saving money if you so desperately want a wider jaw
So your jaw is made up by different muscles. The main muscles are the masseter, temporalis and the medial/lateral pterygoid.
Your jaw muscles have different functions:

So how can you train these functions? You cant add external resistance so you will do isometrics for them. For the masseter you will train jaw elevation by doing a max effort isometric jaw clench, to train the temporalis you will train jaw depression by doing a max effort isometric jaw opening:

To train the medial and lateral pterygoid you will do a max effort jaw protraction and retraction. For protraction you will do a max effort isometric jaw push forward and for retraction you will do a max effort isometric jaw pull they also lateral excursion which you can do a max isometric jaw push to each side:

Now will this be effective??? Probably not i dont even know lol. But physiologically speaking its the only possible way. I am making this post to kinda shit on all the stupid retarded methods out there and show something that could potentially work. Do I recommend this? Hell no. Youll probably end up with TMJ. So just get lean and start saving money if you so desperately want a wider jaw