exercises aiming to increase the range of mandibular movements are commonly involved. Jaw exercises aim to directly oppose the negative effects of disuse that may occur in TMD, due to pain discouraging people from moving their jaw. After initial instruction, people are able to perform a physical therapy regimen at home. The most simple method is by regular stretching within pain tolerance, using the thumb and a finger in a "scissor" maneuver. Gentle force is applied until pain of resistance is felt, and then the position is held for several seconds. Commercial devices have been developed to carry out this stretching exercise (e.g. the "Therabite" appliance). Over time, the amount of mouth opening possible without pain can be gradually increased. A baseline record of the distance at the start of physical therapy (e.g. the number of fingers that can be placed vertically between the upper and lower incisors), can chart any improvement over time. It has been suggested that massage therapy for TMD improves both the subjective and objective health status. "Friction massage" uses surface pressure to causes temporary ischemia and subsequent hyperemia in the muscles, and this is hypothesized to inactivate trigger points and disrupt small fibrous adhesions within the muscle that have formed following surgery or muscular shortening due to restricted movement. Occasionally physiotherapy for TMD may include the use of transcutaneous electrical nerve stimulation (TENS), which may override pain by stimulation of superficial nerve fibers and lead to pain reduction which extends after the time where the TENS is being actually being applied, possibly due to release of endorphins. Others recommend the use of ultrasound, theorized to produce tissue heating, alter blood flow and metabolic activity at a level that is deeper than possible with surface heat applications. There is tentative evidence that low level laser therapy may help with pain. The goals of a PT in reference to treatment of TMD should be to decrease pain, enable muscle relaxation, reduce muscular hyperactivity, and reestablish muscle function and joint mobility. PT treatment is non-invasive and includes self-care management in an environment to create patient responsibility for their own health. Therapeutic exercise and Manual Therapy (MT) are used to improve strength, coordination and mobility and to reduce pain. Treatment may focus on poor posture, cervical muscle spasms and treatment for referred cervical origin (pain referred from upper levels of the cervical spine) or orofacial pain . MT has