Gross anatomical study of the human palatopharyngeus muscle throughout its entire course from origin to insertion

The palatopharyngeus (PP) extends throughout the entire length of the pharynx and probably plays an important role in deglutition, but its spatial distribution remains undefined in some respects. This study was designed to clarify the exact distribution of the PP indispensable for understanding its functions. Using 50 cadavers, the PP and its neighboring muscles were bilaterally exposed in both surfaces of the pharynx. The PP was composed of two divisions: longitudinal and transverse. It is already known that the longitudinal PP is divided into two fasciculi sandwiching the levator veli palatini (LVP) immediately after originating from the palatine aponeurosis. However, we newly discovered a fasciculus originating from the uvula, and further regarded the salpingopharyngeus as another fasciculus of origin. The four fasciculi united to descend through the palatopharyngeal arch and inserted into the thyroid cartilage and beneath the mucosa of the hypopharynx. The transverse PP occupied a location transitional between the PP and superior constrictor (SC), where it originated from the palatine aponeurosis and passed dorsally to encircle the pharyngeal isthmus and reach the pharyngeal raphe. Although whether it belongs to the PP or SC has remained controversial, we regarded it as a portion of the PP from the evolutionary perspective and proposed anatomical criteria for differentiating it from the SC. The wide distribution of the PP suggests that it acts not only to elevate the pharynx or depress the soft palate, but also as a nasopharyngeal sphincter when closing the pharyngeal isthmus.