The strongest muscle based on its weight is the masseter. With all muscles of the jaw working together it can close the teeth with a force as great as 55 pounds on the incisors or 200 pounds on the molars.
The masseter originates at the cheekbone (zygomatic arch) and inserts at the lower jaw (mandible).
Chronically tight, hyperactive masseter may be responsible for teeth grinding at night, chronic jaw tension, and TMJ Syndrome.
Massage is a surprisingly effective way to release tension in the masseter. Both attachments at the origin and insertion are easily accessible by hand, and a skillful massage therapist is able to treat this muscle within a single massage session, although a series of massages are often required to relieve chronic tension.
Massage is not a guaranteed fix for this muscle issues, and should simply be included in the overall strategy of dealing with TMJ, and other jaw conditions.