Discussion of clinical anatomy of the lingual nerves.

The tongue has various functions, such as gustation, pronunciation, mastication, and deglutition. The nerve fibers are complexly intermingled, and communications between the lingual nerve and the hypoglossal nerve have been reported. Fifteen Japanese heads (30 sides) donated to the 2nd-year students dissection course at the Nippon Dental University School of Life Dentistry, Niigata, were studied with regard to the following aspects: 1. relation of the bifurcation between the lingual and the inferior alveolar nerves close to the oval foramen; 2. distance between the oral foramen and the bifurcation of the lingual and inferior alveolar nerves; and 3. communication between the lingual and hypoglossal nerves. Three types of bifurcation were observed. The standard bifurcation was observed in 21 cases (70.1%). A high bifurcation was observed in 5 cases (16.6%), and a communicating bifurcation was observed in 4 cases (13.3%). The average distance between the oval foramen and the bifurcation of the lingual and inferior alveolar nerves was 8.7 +/- 4.2 mm (minimum: 0 mm/maximum: 14 mm). An anterior-type communication between the lingual and hypoglossal nerves was observed in 8 cases (26.6%), a posterior-type was observed in 17 cases (56.7%), and no communication was observed in 5 cases (17.7%).