Liigesketas

Liigesketas, known in English as the articular disc, is a fibrocartilaginous structure found within some synovial joints. It is a dense connective tissue disc that divides the joint cavity into two separate synovial compartments, helping to improve joint congruence, distribute loads, and guide smooth movement between articulating surfaces.

Location and examples

Articular discs occur in a number of joints, with the temporomandibular joint (TMJ) being the best known. In the TMJ, the disc lies between the mandibular condyle and the temporal bone, creating an upper and a lower joint compartment. Other joints that may contain an articular disc include certain shoulder, sternoclavicular, and wrist joints, where the disc aids stability and motion.

Structure and properties

The liigesketas is primarily made of dense fibrous connective tissue with embedded fibrocartilaginous elements. The central region is usually thinner and more fibrous, while the peripheral portions are thicker and more supportive. It is relatively avascular in its inner parts, with vascularization concentrated at the edges, and it contains sensory innervation that contributes to proprioception and pain perception.

Function and clinical relevance

The disc serves to cushion articulating surfaces, reduce friction, and stabilize joint motion. If the disc is displaced or damaged, individuals may experience joint sounds, pain, or restricted movement, particularly in the TMJ. Diagnosis typically involves clinical examination and imaging, and treatment ranges from conservative approaches (rest, physical therapy, splints) to surgical options in some cases.

Etymology and usage

In Estonian, liigesketas directly translates to “articular disc,” emphasizing its role as a joint-associated fibrocartilaginous structure.