title: Fetal anatomy of the upper pharyngeal muscles with special reference to the nerve supply: is it an enteric plexus or simply an intramuscular nerve?
abstract: We examined pharyngeal nerve courses in paraffin-embedded sagittal sections from 10 human fetuses, at 25-35 weeks of gestation, by using S100 protein immunohistochemical analysis. After diverging from the glossopharyngeal and vagus nerves at the level of the hyoid bone, the pharyngeal nerves entered the constrictor pharyngis medius muscle, then turned upward and ran superiorly and medially through the constrictor pharyngis superior muscle, to reach either the levator veli palatini muscle or the palatopharyngeus muscle. None of the nerves showed a tendency to run along the posterior surface of the pharyngeal muscles. Therefore, the pharyngeal nerve plexus in adults may become established by exposure of the fetal intramuscular nerves to the posterior aspect of the pharyngeal wall because of muscle degeneration and the subsequent rearrangement of the topographical relationship between the muscles that occurs after birth.
authors.affiliation: Department of Anatomy, Tokyo Dental College, Chiba, Japan. ; Oral Health Science Center hrc8, Tokyo Dental College, Chiba, Japan.
authors.forename: Shinichi
authors.initials: S
authors.lastname: Abe
authors.forename: Masayuki
authors.initials: M
authors.lastname: Fukuda
authors.forename: Shigeki
authors.initials: S
authors.lastname: Yamane
authors.forename: Hideki
authors.initials: H
authors.lastname: Saka
authors.forename: Yukio
authors.initials: Y
authors.lastname: Katori
authors.forename: Jose Francisco
authors.initials: JF
authors.lastname: Rodríguez-Vázquez
authors.forename: Gen
authors.initials: G
authors.lastname: Murakami
keywords: Constrictor pharyngis superior muscle; Glossopharyngeal nerve; Human fetus; Levator veli palatini muscle; Pharyngeal nerve plexus