Vagal communicating branches between the facial and glossopharyngeal nerves, with references to their occurrence from the embryological point of view.

A rare and hitherto not reported case in which a branch of the vagal nerve communicated simultaneously with the facial and the glossopharyngeal nerves was encountered in the body of a Japanese male cadaver in an anatomy class. This vagofacial-vagoglossopharyngeal (X.VII-X.IX) communicating branch was found to issue from the vagal nerve truck in close association with the pharyngeal branches (rami pharyngei nervi vagi), bifurcating soon into a vagofacial (X.VII) and a vagoglossopharyngeal division (X.IX). The X.VII division coursed forward and reached the posterior belly of the digastric muscle; after entering this muscle, this division broke up into filaments to communicate with the ramus digastricus of the facial nerve which was found to play an equivalent role in making the vagofacial ansa. The X.IX division, in contrast, took its course medially to reach the stylopharyngeal muscle. After entering this muscle, the X.IX division communicated with the stylopharyngeal branch of the glossopharyngeal nerve, which was found to be the equivalent to the X.IX division; these two form together the vagoglossopharyngeal ansa. Therefore, it could be concluded that the X.VII-X.IX communicating branch constitutes the vagal moieties of the vagofacial as well as the vagoglossopharyngeal ansae. The background of the appearance of the communicating branches observed in this report is discussed in the text from the developmental viewpoint on the basis of the findings obtained in chick embryos stained in whole mounts with anti-neurofilament protein antibody.