Anatomy of the human temporomandibular joint. An updated comprehensive review.

This article is an in-depth review of the current knowledge on human temporomandibular joints (TMJ's). All aspects of joint anatomy are described with emphasis on adaptability to biochemical stimuli throughout life. Each TMJ is a pressure-bearing compound double synovial joint. TMJ's are unique in having a movement not only controlled by the morphology of the joint per se but also by the dentition at the other end of the lever system. During life the temporal, condylar and discal articular surfaces undergo remodelling. The synovium is an important joint component which contributes to nourish and lubricate the avascular surfaces and has bactericidal properties. The joint capsule has privileged relationships anteriorly with the lateral pterygoid muscle. This muscle has two heads that show functionally reciprocal activation. The exact insertion and role of the superior head of the lateral pterygoid muscle remains controversial. The disc has a very low coefficient of friction and compensates for the lack of congruence between articular surfaces. Biomechanically it is stabilized between condyle and articular eminence by its thick rim which has special viscoelastic properties. Apart from the viscoelastic deformations the other important mechanism of disc stabilization seems to be related with the structure of some of the disc attachments.