Structure and Development of the Temporomandibular Joint - Joint capsule - Articular disc - Mandibular condyles - Articular surface of the temporal bone - Temporomandibular ligament - Capsule is a thin, loose envelope attached to mandibular fossa and articular tubercle - Articular disc is composed of dense fibrocartilagenous tissue and divides the joint into upper and lower compartments - Ligaments include the temporomandibular ligament, stylomandibular ligament, and sphenomandibular ligament - Joint formation begins around 12 weeks of gestation - Mesenchyme forms the fibrous joint capsule - The developing lateral pterygoid muscle attaches to the fetal disc - The disc extends posteriorly through the petrotympanic fissure and attaches to the middle ear - The mandibular condyle has a growth center with hyaline cartilage that allows for bone growth

Function and Jaw Movement of the Temporomandibular Joint - Temporomandibular joint is a ginglymoarthrodial joint, combining hinging and sliding movements - Mandibular condyle articulates with the temporal bone in the mandibular fossa - An articular disc divides the joint into two compartments - Rotation occurs in the lower compartment, while translation occurs in the upper compartment - Resting position of the joint allows for a 2-4mm interocclusal clearance - Normal full jaw opening is 40-50 millimeters - Mandible moves during jaw movements, not the maxilla - Excursions include lateral movements, forward (protrusion), and backward (retrusion) movements - Protrusion involves translation of the condyle without significant rotation

Clinical Significance and Pathologic Conditions of the Temporomandibular Joint - Temporomandibular joint pain can be caused by myofascial pain dysfunction syndrome - Internal derangements, such as disc displacement, can also cause pain - Osteoarthritis is a degenerative joint disease affecting the temporomandibular joint - Temporal arteritis can cause pain and is considered a diagnostic criteria - Temporomandibular joint dysfunction (TMD) refers to a group of problems affecting the joint and associated tissues - Chondrosarcoma and osteosarcoma are rare conditions that can affect temporomandibular joint function - Other conditions may cause pain and swelling in the joint - Proper diagnosis and treatment are essential for managing these pathologic conditions - Regular dental and medical check-ups can help detect and address any issues with the temporomandibular joint

Examination and Disc Displacement in the Temporomandibular Joint - Temporomandibular joints can be felt in front of or within the external acoustic meatus during mandibular movements - Auscultation of the joint can be performed - The most common disorder of a temporomandibular joint is disc displacement - Disc displacement occurs when the articular disc moves out from between the condyle and the fossa - Disc displacement is usually very painful - The articular disc is attached anteriorly to the superior head of the lateral pterygoid muscle and posteriorly to the retrodiscal tissue - Disc displacement causes the mandible and temporal bone to make contact on something other than the articular disc - In most instances of disc displacement, the disc is displaced anteriorly upon translation - Disc displacement with reduction is characterised by a pop or click sound upon opening and closing of the mouth

Temporomandibular Disorder (TMD) and Fibromyalgia - TMD is pain and dysfunction of the TMJ and the muscles of mastication - TMD represents a range of distinct disorders with multifactorial etiology - TMD is the second most frequent cause of orofacial pain after dental pain - The pathophysiology of TMD is poorly understood - TMD accounts for the majority of pathology of the TMJ - Fibromyalgia is a condition associated with TMD - Fibromyalgia is characterised by widespread musculoskeletal pain and fatigue - Fibromyalgia is more common in women than in men - The exact cause of fibromyalgia is unknown - Fibromyalgia often coexists with other chronic pain conditions