The temporomandibular joint (TMJ) is classified as a synovial joint that permits gliding, rotation, elevation, and depression and normally functions in mastication, suckling, swallowing, yawning, speaking, and biting. The mandibular fossa, the articular eminence of the temporal bone, and the mandibular condyle all contribute to the TMJ. This joint can be indicated by the eminentia mandibularis, a bony protuberance on the floor of the middle cranial fossa. The articular eminence is a convex bony elevation on the root of the zygomatic process that characterizes the most anterior boundary of the mandibular fossa. Both the fibrous capsule and the lateral ligament attach to the articular eminence, and the capsule also attaches to the articular cartilage of the temporal bone and the neck of the mandible. The articular surfaces of the TMJ are uniquely lined with fibrocartilage rather than the normal hyaline cartilage. Its joint cavity is divided into two (superior and inferior joint spaces) by an articular disc, and this disc attaches to the capsule separating the two joint spaces lined with synovial membranes. The synovial membranes do not extend to cover the disc or the articular surfaces. The joint moves and functions via the lateral, stylomandibular, and sphenomandibular ligaments. The ligamentous muscles that allow for TMJ articulation are the temporalis, masseter, medial, and lateral pterygoids, collectively known as the muscles of mastication. The suprahyoid muscle group (digastric, mylohyoid, geniohyoid, and stylohyoid) is also responsible for mandibular movement. The synovial joints are supplied by sensory nerve endings (mainly proprioceptive) with pain and stretch receptors. The articular capsules and ligaments are highly vascularized, forming capillary networks over the synovial membranes. From a clinical perspective, understanding the anatomy and variations of the TMJ is significant for TMJ surgery, diagnosis of temporomandibular joint disorder, and related diseases and treatments.
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