The diagnosis of functional temporo-mandibular and cervical problems depends to a great extent on subjective information provided by patients. As a result, it is difficult to arrive at a substantiated assessment of the prevalence of these disorders. Based on the data reported from large-scale epidemiological studies, it appears that nearly 50 % of the populations of developed countries have symptoms of musculo-skeletal problems. The over-abundance of diagnostic tests suggested for assessing this problem adds confusion to this murky area. The purpose of this article is to precisely evaluate the pertinence of the various tests used to establish a clinical diagnosis.