This book studies the biomechanics and functional anatomy of temporomandibular joint and disorders related to it. Temporomandibular disorders (TMD) is a collective term that embraces a number of clinical conditions that involve the masticatory musculature and/or temporomandibular (TM) joints and associated structures. Various clinical conditions are characterized by pain in the preauricular area, TM joint, or muscles of mastication; limitation or deviation in mandibular range of motion; and TM joint sounds (clicking, popping, crepitus) during mandibular function. As with other musculoskeletal disorders, pain during function and/or at rest is the primary reason patients seek treatment, and reduction in pain is generally the primary goal of therapy.