Spatial relationship between the palatopharyngeus and the superior constrictor of the pharynx

The palatopharyngeus and the superior constrictor act during swallowing. However, because they overlap one another, their morphologies have been controversial. This study examined these muscles to clarify their configuration and interrelationships. The attachments and the fiber arrangement of the superior constrictor and the palatopharyngeus were gross anatomically examined in 28 Japanese cadavers. The most superior fibers of the superior constrictor arose from the palate and interfused with the lateral fibers of the palatopharyngeus. Consequently, their origins and insertions were arranged in a continuous line, respectively, and these flat muscles formed a sheet. The palatopharyngeus rotated 90 degrees, from the origin to the insertion, about its long axis, and its superior and inferior surfaces turned into internal and external, respectively. Its lateral fibers passed on the internal surface of the superior constrictor, and these two muscles were inserted into the pharyngeal raphe with an overlap, indicating that the muscular sheet was folded back. Its medial fibers consisted of two layers at the origin and were interdigitated with the insertion of the levator veli palatini. The superior layer was joined by the salpingopharyngeus and dispersed into the pharyngeal wall. The inferior one was joined by the stylopharyngeus and descended along the palatopharyngeal arch to be inserted into the thyroid cartilage and the epiglottis. These two muscles formed a sheet that was partially folded back. It is suggested that the superior constrictor and the lateral fibers cooperate as sphincters, and the medial fibers and the stylopharyngeus as elevators.