The extended bundle of the tensor veli palatini: Anatomic consideration of the dilating mechanism of the Eustachian tube

Objective The aim of this study was to analyze the topographical structures of the muscles surrounding the Eustachian tube. Materials and methods We conducted macroscopic and histological studies of 24 halves of 12 heads from Japanese cadavers. Results The main findings were as follows: 1) the infero-lateral muscle bundles of the tensor veli palatini didn’t turn medially at the pterygoid hamulus but were distributed laterally and continuous with the buccinator; 2) the tensor veli palatini attached laterally to the membranous part of the Eustachian tube; 3) the superior pharyngeal constrictor was not only adjacent to the buccinator at the pterygomandibular raphe but also had muscular continuation with it laterally and 4) some bundles of the superior pharyngeal constrictor adhered with the palatine aponeurosis. Conclusion We believe that the cooperation of the muscles contributes to the dilating mechanism of the Eustachian tube, due to the complex topographical structures of the surrounding muscles: the tensor veli palatini, the levator veli palatini, the superior pharyngeal constrictor and the buccinator.