The masseter muscle is an integral part of the oral facial complex and one of 
the muscles of mastication. It functions with the other masticatory muscles in 
moving and posturing the mandible and in verbalizing, eating and swallowing. 
When a patient has temporomandibular dysfunction (TMD) or a myogenic disorder, 
the integrity of the masseter muscle can be compromised resulting in pain, 
malfunction, inflammation and/or swelling. A careful evaluation of the masseter 
muscles is necessary in facial pain patients since the pain can originate from a 
distant site and be referred to this area. One of the little known disorders 
involving the masseter and its tendinous origin is tenomyositis, in which an 
inflammation of the muscle and its tendon occurs. In this retrospective study, 
the charts of 114 consecutive patients (N = 114) were evaluated to determine the 
prevalence of this disorder and the reported etiology.