[Anatomical study of the tonsillar bed: the topographical relationship between the palatine tonsil and the lingual branch of the glossopharyngeal nerve].

The topographical relationship between the lingual branch of the glossopharyngeal nerve (LBGN) and the muscle layer of the palatine tonsillar bed was investigated by gross and histological observation in 107 sides of 83 Japanese adult cadavers, aged 27-88yr, in order to provide anatomical data facilitating the prevention of taste disturbance caused by injury to the LBGN during tonsillectomy. The muscular composition and lamination of the tonsillar bed are thought to be unchanged by aging or pathological conditions such as inflammation, in contrast to the morphological instability of the palatine tonsil itself. In the present study, the nerve branch was often (23.4%) observed to pass along the inferior side of the styloglossus muscle and to be located lateral to the superior constrictor pharyngeal muscle, during almost its entire course to the base of the tongue, so that the palatine tonsil was clearly separated from the LBGN. In 55.1% of cases, however, the muscle lining observed at the tonsillar bed was not continuous, and instead thin muscle bundles, derived from the stylopharyngeus, palatopharyngeus or superior constrictor pharyngeal muscles, partly covered the tonsillar capsule externally. Moreover, in 21.5% of cases, the LBGN was firmly adherent to the tonsillar capsule, due to complete absence of the lining muscles at the tonsillar bed. In these cases, and also probably in a similar percentage of patients undergoing tonsillectomy, taste disturbance could occur upon removal of the hypertrophic tonsillar capsule produced by chronic inflammation. Therefore, tonsillectomy with minimal disturbance of the tonsillar bad is recommended in all cases.