Temporalis is a large, scallop-shaped muscle covering the side of the head above and behind the ear.
Masseter starts at the cheek bone on the side of the face and goes down to the jaw bone and is used mainly when chewing.
People who clench their jaws or grind their teeth will find these muscles quite tender and tight which can led to headaches through the side of the head, and/or above the eyes as well as jaw problems. In some cases it may also cause tinnitus (ringing in the ears).
Massage can help relieve this tightness however, it can be quite painful, so it is important to let your massage therapist know how much pressure to apply. Your masseuse may also recommend gentle jaw stretches to help ease this muscle after your massage treatment.
Basic Clinical Massage Therapy, 2003.