Injection of the temporomandibular joint is indicated as an important component in the management of temporomandibular joint dysfunction, in the palliation of pain secondary to internal derangement of the joint, and in the treatment of pain secondary to arthritis of the joint. Temporomandibular joint dysfunction (also known as myofascial pain dysfunction of the muscles of mastication ) is characterized by pain in the joint itself that radiates into the mandible, ear, neck, and tonsillar pillars. Headache often accompanies the pain of temporomandibular joint dysfunction and is clinically indistinguishable from tension-type headache. Stress is often the precipitating or exacerbating factor in the development of temporomandibular joint dysfunction. Dental malocclusion may also play a role in the evolution of temporomandibular joint dysfunction. Internal derangement and arthritis of the temporomandibular joint may manifest as clicking or grating when the joint is opened and closed and may be easily heard on auscultation of the opening and closing joint ( Figures 1-1 and 1-2 ). Plain radiographs and computerized tomography may help identify arthritic changes, with magnetic resonance imaging useful in identifying articular disk abnormalities ( Figure 1-3 ). If the condition is not promptly treated, the patient may experience increasing pain in the just-mentioned areas and limitation of jaw movement and opening. Recently, the injection of autologous blood and platelet-rich plasma into the temporomandibular joint has gained popularity in the treatment of recurrent temporomandibular joint hypermobility dislocation ( Figure 1-4 ). This injection technique is also useful in the injection of other substances into the temporomandibular joint, such as hyaluronic acid derivatives and tenoxicam.