Intra-oral stretching jaw muscles (Masseter stretch, intra-oral, sitting)

Sit upright with your feet flat on the floor.
Place your thumb on the inside of your cheek and your index and middle finger on the outside of your cheek over the muscle
Start with your thumb at the deep end of the muscle.
Gently stretch the muscle by moving your thumb out towards your fingers without adding pressure from the fingers.
Slide your thumb from the starting position to the front of the cheek.
Keep your jaw relaxed during the exercise.
Perform this exercise on the affected side as instructed by your clinician.