The masseter muscle runs down the rear part of the cheek, from the cheek bone down to the lower jaw on both sides of the face. The muscle is one of the important muscles involved in chewing food and talking, it’s function is to close the jaw. The masseter muscle becomes enlarged if there is frequent clenching or grinding of teeth (bruxism). This results in unequal enlargement of the muscle, causing facial asymmetries, increased muscle bulk, and an overly-square or masculine-looking jawline. Depending on the degree of enlargement, you may consider a surgical reduction of the masseter muscle or a non-surgical treatment such as the use of toxin (same toxin used for anti-wrinkle treatments)