Capsule

The last tissue to be considered is the articular capsule. The attachment points of the capsule have already been discussed. It is important to realize that this capsule is an incomplete structure. That is, the capsule does not extend posterior of the condyle. In fact, the posterior part of the TMJ is bounded by the tympanic plate on the medial two-thirds of the joint and by external ear cartilage on the lateral third. On the lateral part of the joint, the capsule is a well-defined structure that functionally limits the forward translation of the condyle. This capsule is reinforced more laterally by an external TMJ ligament, which also limits the distraction and the posterior movement of the condyle. Medially and laterally, the capsule blends with the condylodiscal ligaments. Anteriorly, the capsule has an orifice through which the lateral pterygoid tendon must pass. This area of relative weakness in the capsular lining becomes a source for possible herniation of intra-articular tissues, and this in part may allow for forward displacement of the disc.