The relationship between the temporomandibular joint capsule, articular disc and jaw muscles.

The anatomy of the temporomandibular joint capsule and its possible relationships to other structures near the joint are not fully understood. A 3-dimensional analysis based on sagittal, frontal and horizontal serial sections through the human temporomandibular joint region was therefore undertaken. Capsular elements which directly connect the temporal bone with the mandible were seen only on the lateral side of the joint. In the posterior, anterior and medial regions of the joint the upper and lower laminae of the articular disc are attached separately either to the temporal bone or to the mandibular condyle. The shaping of the articular cavities and the texture of the joint capsule permit movements of the articular disc predominantly in the anteromedial direction. On the entire medial side of the joint the articular disc and its capsular attachments are in close contact with the fascia of the lateral pterygoid muscle whereby a small portion of the upper head of this muscle inserts directly into the anteromedial part of the articular disc. Thus both the upper and the lower heads of the lateral pterygoid muscle are likely to influence the position of the articular disc directly during temporomandibular joint movements. Laterally, the articular disc is attached to the fascia of the masseter muscle, and part of the lateral ligament inserts into the temporalis fascia. Since these attachments are relatively weak, neither the temporalis nor the masseter muscles are considered to act directly on the articular disc; instead, via afferents from muscle spindles, they may take part in signalling the position of the temporomandibular joint components, including that of the articular disc.