Anatomy of inferior end of palatopharyngeus: its contribution to upper esophageal sphincter opening
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LARYNGOLOGY
Anatomy of inferior end of palatopharyngeus: its contribution to upper esophageal sphincter opening Keiko Fukino1 · Masahiro Tsutsumi2 · Akimoto Nimura3 · Koh Miwa2 · Takashi Ono1 · Keiichi Akita2 Received: 18 June 2020 / Accepted: 12 October 2020 © The Author(s) 2020
Abstract Purpose The palatopharyngeus is one of the longitudinal pharyngeal muscles which contributes to swallowing. It is reported that the palatopharyngeus has muscle bundles in various directions and with attachment sites, and each muscle bundle has a specific function. Although previous reports suggest that the palatopharyngeus is partly interlaced with some parts of the inferior constrictor, the precise relationship remains unclear. The purpose of this study was to examine the precise manner of the connection between the palatopharyngeus and inferior constrictor, and to examine the histological characteristics of this connection. Methods We examined 15 halves of nine heads from Japanese cadavers (average age: 76.1 years); 12 halves, macroscopi‑ cally, and three halves, histologically. Results Our observation suggests that the palatopharyngeus spreads radially on the inner aspect of the pharyngeal wall. The most inferior portion of the palatopharyngeus extended to the inner surface of the cricopharyngeal part of the inferior constrictor. Histological analysis showed that the inferior end of the palatopharyngeus continued into the dense connective tissue located at the level of the cricoid cartilage. The dense connective tissue not only covered the inner surface of the inferior constrictor but also entered its muscle bundles and enveloped them. Conclusion Therefore, the palatopharyngeus interlaced the cricopharyngeal part of the inferior constrictor through the dense connective tissues. The findings of this study show that the palatopharyngeus may act on the upper esophageal sphincter directly and help in its opening with the aid of the pulling forces in the superolateral direction. Keywords Palatopharyngeus · Inferior constrictor · Upper esophageal sphincter · Swallowing · Deglutition disorder
Introduction The opening of the upper esophageal sphincter (UES), which is located on the cricopharyngeal part of the inferior con‑ strictor and the uppermost part of the esophagus [1–4], is * Keiichi Akita [email protected] 1
Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1‑5‑45 Yushima, Bunkyo‑ku, Tokyo 113‑8549, Japan
2
Department of Clinical Anatomy, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), 1‑5‑45 Yushima, Bunkyo‑ku, Tokyo 113‑8519, Japan
3
Department of Functional Joint Anatomy, Graduate School of Medical and Dental Science, Tokyo Medical and Dental University, Tokyo, Japan
one of the essential events required for proper swallowing [5, 6]. In general, the UES opening occurs as a result of the elevation of the hyolaryngeal complex and the relaxa‑ tion of the cricopharyngeal part of the i
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