[Anatomical study of the human lingual muscle. Myofibrous organization of the extrinsic muscles].

The organization and distribution of fibre types in the extrinsic human muscles of 34 males and 19 females were determined by Sudan black B staining. 1) According to our observation, the Genio-hyo-glossus consists of two large bundles; and upper bundle and a lower bundle. The Hyo-glossus is thin, flat and the Stlo-glossus is shorter and smaller. 2) These muscles are composed of small bundles of the fibre which could be seen under microscopic. These contain many small fatty cells. 3) The cross-sectional area (mm2) and the total number of the muscle fibres is highest in the Genio-hyo-glossus. The number of fibres per mm2 is highest in of the Hyo-glossus. The cross-sectional size of muscle fibre (micron) in the Stlo-glossus is generally larger than others. 4) Comparison with other muscles as in sucking show the muscle fibre size in the laryngeal muscles to be greatest. The Cross-sectional area and the total number of muscle fibre is greatest in the Genio-hyo-glossus. 5) Three fibre types of muscle could be discerned in terms of their reaction to pigments and cellular: red muscle fibre a positive reacted positively; white muscle fibres has a weak reaction; intermediate muscle fibres reacted intermediately. White muscle fibres are localized in the external layer, in contrast to red and intermediate muscle fibres which are localized in the inner layer of the extrinsic muscles. The percentage distribution of red muscle fibres in the Hyo-glossus and Stlo-glossus is more than Genio-hyo-glossus. These results suggest that Genio-hyo-glossus acts as a power generating force in contrast to the Hyo-glossus and Stlo-glossus which are fatigue-resisting.