ANATOMICAL SIGNIFICANCE OF THE SPATIAL DISTRIBUTION OF THE PALATOPHARYNGEUS WITH REGARD TO CLOSURE OF THE NASOPHARYNX

Abstract

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Background. Production of nasopharyngeal closure should be accomplished by the coordination of the various soft palate and pharyngeal muscles. However the anatomical basis of the functional roles of these muscles still remains unclear. Aim. In the present study, we macroscopically and microscopically examined these muscles in detail, especially palatopharyngeus (PP) in order to realize whether specific muscle bundles have specific functions during nasopharyngeal closure. Material and Methods. Forty halves of 21 heads from Japanese cadavers (average 83.9 years) were used (37 halves of 19 heads for macroscopic examinations, and three halves of two heads for histological examinations). Results and Discussion. The most superior muscle bundle of the superior constrictor (SC) and most lateral muscle bundle of PP originated from the superior surface of the palatine aponeurosis, initially ran in parallel, and subsequently ran superoposteriorward and inferoposteriorward, respectively. PP spread radially on the internal surfaces of the pharyngeal muscles as a single continuous sheet. A fold of the sheet continuing to the median portion of the palatal muscles roughly established the palatopharyngeal arch, and the stylopharyngeus (StP) attached to the base of the arch. Conclusions. PP as a whole muscle sheet could show various functions: as a sphincter along with SC in some cases and as an elevator along with StP. In addition, PP could also show the function of the medial protrusion by forming the thick palatopharyngeal arch along with StP and SC. It is considered that PP could play a most important role in nasopharyngeal closure.