A Consideration of the Normal and Abnormal Human Suprahyoid and Infrahyoid Musculature

Abstract

An abnormal cleidohyoid muscle, an excess anterior belly muscle of the digastric and a levator thyroid gland muscle are reported in the suprahyoid and infrahyoid musculature of Japanese male cadavers (Case A) 65 years and (Case B) 46 years old. The muscle weight, cross-sectional area of the transverse muscle section, number of muscle fibers per mm2 and the average size of the muscle fibers of these abnormal muscles were compared with simmilar parameters of normal suprahyoid and infrahyoid muscles. In the normal muscles, the anterior belly of the digastric muscle and geniohyold were most developed among other hyoid musculature. In case A, the number of muscle fibers per mm2 of all the abnormal muscle was smaller than in normal hyoid muscles and the average size of muscle fibers was smaller. In case B, the number of muscle fibers per mm2 of all the abnormal muscles was larger than in normal hyoid muscles but the average size of the abnormal muscle fibers was smaller.