Morphological study of the superior pharyngeal constrictor muscle

Objectives: To clarify the details morphology of the superior pharyngeal constrictor muscle in humans during ingestion movement, we examined the macroscopic characteristics of the pterygopharyngeal, buccopharyngeal, mylopharyngeal and glossopharyngeal parts of the muscle. Methods: 37 cadavers of Japanese adults that had been fixed in 10% formaldehyde and stored at the Department of Anatomy in Tokyo Dental College were used. The superior pharyngeal constrictor muscle was observed from the facial and oral sides. Results: The superior pharyngeal constrictor muscle at the pterygopharyngeal part originated between the pterygoid hamulus of the sphenoid bone and the posterior margin of the medial pterygoid plate to form the most superior area of the pharyngeal wall. Morphology of the origin of the muscle at the buccopharyngeal part could be divided into three types: type I, membranous morphology from superior to inferior areas; type II, membranous only in superior area; and type III, complete lack of membrane. Morphology of the origin of the muscle at the mylopharyngeal part could be divided into two types: type I, tip of the origin of the muscle on the mylohyoid line; and type II, tip of the origin of the muscle away from the mylohyoid line. The muscle at the glossopharyngeal part originated from the root of the tongue in all cases. Muscles originating from these four parts merged immediately after the origin and were aligned transversely towards the posterior pharyngeal wall. Conclusion: This study clarified that the superior pharyngeal constrictor muscle came into contact with the buccinator muscle without intervention of the bone and originated from the mandible and root of the tongue. These findings suggest that the superior pharyngeal constrictor muscle plays an important role in the expression of smooth coordinated movements associated with ingestion movement from mastication to swallowing.