[Role of the lateral pterygoid muscle in mandibular movements]

The two bundles, superior and inferior, of the lateral pterygoid muscle were studied by EMG and integrated EMG during various movements of the mandible in 36 children and 2 adults. At the same time, the EMG of other masticatory muscles was also recorded. The functional specialization of the two bundles is expressed by different levels of recruitment: In the inferior bundle (pterygo-condylian,) electrical activity is stronger in the movements of opening, antepulsion and controlaterality. In the superior bundle (spheno-meniscal), activity is stronger in the movements of occlusion and retraction. Thus the inferior bundle principally has a function of stabilization of the temporomandibular joint.