Morphofunctional changes of orofacial muscles in patients with unilateral or bilateral cleft lip, alveolus and palate.

The facial musculature is part of a biocybernetic feedback system within the stomatognathic system, the continuity of which is disturbed by clefts of the lip, jaw, and palate (cheilognathopalatoschisis). This results in topographic, fine-structural and functional alterations of the facial musculature. In two heads with unilateral clefts and two heads with bilateral clefts, the facial musculature was dissected and the M. orbicularis oris macroscopically and topographically examined. We found changes in the attachment of the M. orbicularis oris. The modiolus, which is coresponsible for the proper topographic relation of the M. obicularis oris to the other facial muscles, was unchanged. Further, we examined the vascular system of the muscle, which likewise adapts to the altered situation. Lip/jaw/palatal clefts result in anatomically functional and fine-structural alterations of the M. orbicularis oris, while the rest of the facial musculature remains unchanged.