A Study of the Mechanism of Velopharyngeal Closure

Abstract

In an investigation of the palatal origin of the pterygopharyngeus muscle, detailed dissections of the soft palates and pharynges of 10 cadavers were undertaken. The palatopharyngeus and salpingo-pharyngeus muscles were also studied. In 8 of 10 cases the pterygopharyngeus muscle was of palatal origin. In the majority of cases this bundle consisted of a small strand of fibers which originated near the insertion of the levator palati on the palatal aponeurosis. In all cases this muscle had a hamular origin. The hamular origin was the better developed and was just inferior to the smaller palatal origin. In 8 of 10 cases there were muscle connections between the palatopharyngeus and the pterygopharyngeus muscles. There is considerable variability in general muscular development in the anatomical region. Results of this study suggest that, in addition to their hamular divisions, the pterygopharyngei receive fibers which originate in the soft palate; the palatal fibers of the pterygopharyngei may contribute to mesial movement of the pharyngeal walls during velopharyngeal closure; muscular connections between the palatopharyngeus and the pterygopharyngeus muscles normally exist; because of these connections, the approximation of the palatopharyngei during velopharyngeal closure may contribute to the mesial movement of the lateral pharyngeal walls; in addition to their insertions into the lateral pharyngeal walls, the salpingopharyngeus muscle may occasionally send fibers to the soft palate; the salpingopharyngeus muscle may contribute to velopharyngeal closure by creating an in-bulging of the lateral pharyngeal walls, and this muscle may also contribute slightly to the elevating of the soft palate. Four cleft palate subjects and 1 subject who had a carcinoma of the left maxillary sinus with a radical resection were studied for movement of the velum by x-ray and other methods. General conclusions from both the anatomic and physiologic studies are: Palatal fibers of the superior constrictor typically exist and probably account for a part of the anterior and mesial movement of the pharyngeal walls; muscular connections between the palatopharyngei and pterygopharyngei typically exist and may account for some of the mesial movement of the pharyngeal walls; anatomic relationships of the salpingopharyngeus suggest that this muscle probably acts to raise the velum and to move the lateral walls of the pharynx in a mesial direction; considerable mesial movements of the lateral pharyngeal walls exist; mesial movement occurs over a considerable vertical extent, and movement may be greater at a lower level than at its highest position; the amt. of mesial movement is directly related to the extent of velar elevation; greatest extent of mesial movement appears to occur in the area overlying the salpingopharyngeus muscle; although there are significant differences between certain vowel sounds in regard to velar and mesial pharyngeal movements, these differences are not significant for the anterior movement of the posterior pharyngeal wall; and the velopharyngeal mechanism does not function as a simple sphincter.