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intra‐articular discs, mandibular/jaw muscles and occlusion.

      In the simplest terms, the temporomandibular joint is the articulation between the upper and lower jaws. The teeth form the contacts between the upper and lower jaws, and the muscles are the motors that move the mandible. This system is unique in that the TMJs are paired; any stimulus that affects one joint or any other single part of the articulatory system can have a ‘knock‐on effect’ in the rest of the system.

      It is important to have an understanding of anatomy not only to be able to differentiate between what is physiological and what is pathological but also to understand the objectives of some treatment options.

Photo depicts the temporomandibular joint.

      (M. Ziad Al‐Ani, Robin J.M. Gray.)

      1 The articular zone is dense fibrous connective tissue and forms the outer functional surface of the condyle head. As a result of this fibrous connective tissue layer, it is suggested that it is less susceptible to the effect of ageing and breakdown over time. In addition, despite a poor blood supply, it has a better ability to repair, good adaptation to sliding movement, and the ability to act as a shock absorber when compared with hyaline cartilage.

      2 The proliferative zone is mainly cellular and is the area in which undifferentiated germinative mesenchyme cells are found. This layer is responsible for the proliferation of the articular cartilage and the proliferative zone is capable of regenerative activity and differentiation throughout life.

      3 The cartilagenous zone contains collagen fibres arranged in a criss‐cross pattern of bundles. This offers considerable resistance against compressive and lateral forces but becomes thinner with age.

      4 The calcified zone is the deepest zone and is made up of chondrocytes, chondroblasts, and osteoblasts. This is an active site for remodelling activity as bone growth proceeds.

Photo depicts the four distinct zones described in the articular surface of the condyle and mandibular fossa.

      (M. Ziad Al‐Ani, Robin J.M. Gray.)

Photo depicts the joint capsule.

      (M. Ziad Al‐Ani, Robin J.M. Gray.)

      The function of the synovial membrane is considered to be

       regulatory because it controls electrolyte balance and nutrients

       secretory via the interstitial cells

       phagocytic.

      Synovial fluid is a clear, pale‐yellow, viscous solution secreted by the synovial tissues and consists mainly of an ultrafiltrate of plasma enriched with a proteoglycan‐containing hyaluronic acid synthesised by synovial cells. The high viscosity of this fluid is a result of the presence of sodium hyaluronate which provides lubrication. The synovial fluid also allows removal of degradation products from the joint space, lubrication of the joint surfaces, and nutrition of the vascular parts of the joint.

       The temporomandibular ligament

Photo depicts the position of stylomandibular ligament.

      (M. Ziad Al‐Ani, Robin J.M. Gray.)

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