Frenulum
The vestibule of the mouth is the space between the lips and the teeth. If you start in the mid line along the bottom, you can feel the inferior frenulum. Move your finger to the side until it moves up along a ridge, this is the anterior border of the ramus of the mandible. While your finger is on this border, bite down and you will feel the masseter muscle contracting. If you move your finger as far up as you can go, you will feel the coronoid process of the ramus and the tendinous insertion of the temporalis muscle. Now move your finger in the upper recess of the vestibule until you come to the mid line again and you will feel the upper frenulum. Look in your own mouth for the opening of the parotid duct that enters the vestibule opposite the 2nd upper molar tooth.