Masticatory and bite forces, when applied to the teeth, generate tremendous 
compressive energy in the temporomandibular joint (TMJ). Excessive 'TMJ 
loading', if left untreated, deteriorates articular functions. Normally, it is 
controlled, to a certain extent, by stomatognathic means. In an attempt to 
clarify this control mechanism, we analyzed the relationship between TMJ loading 
and the activities of the masticatory muscles, by employing a static 
two-dimensional jaw model. This comprises two rigid bodies, the upper and lower 
jaws, including three dominant muscles, i.e. the masseter, the anterior portion 
of the temporalis and the lateral pterygoid. Static equilibrium analyses 
determined that TMJ loading can be minimized, under controlled bite conditions, 
by pointing the loading vector in a direction solely indicated by individual 
morphological factors, such as the position and orientation of the masseter and 
the temporalis. This theoretically optimum direction of TMJ loading was also 
anatomically acceptable, because the load is applied exactly to those portions 
of the articular disk and mandibular head that can most easily sustain it. 
Interestingly, this factor was absolutely independent of both the activities of 
the lateral pterygoid and the direction of bite force. Consequently. TMI loading 
can be minimized, by coordinating the activities of the masseter and the 
anterior portion of the temporalis.