Cleft palate velopharyngeal musculature in a five-month-old infant: a three dimensional histological reconstruction.

The structure of the velar muscles in a five-month-old infant with a cleft of the secondary palate was studied using the Plexiglas reconstruction method based on serial histological sections. The right side was sectioned horizontally and the left side in the coronal plane. Sections were projected at a magnification of 18, and muscle fibers and bone and mucosal surfaces were drawn on Plexiglas sheets. Each reconstruction was divided into representative levels which were described in detail. The three-dimensional reconstructions vividly demonstrated the anterior insertion of the levator, palatopharyngeus, and uvular muscles, and the abnormal anterior position of the velar muscles generally. The levator muscle appeared to be in a position to obstruct the auditory tube during muscle contraction. The palatoglossus muscle evidently received a substantial contribution of muscle fibers from levator as well as from some fibers originating from the pterygoid hamulus. A bundle of muscle fibers from the tensor muscle did not pass around the pterygoid hamulus but coursed anteriorly to insert on the maxillary tuberosity. The results provided fresh support for the case of intravelar surgical reorientation of the abnormally inserted muscles.