Monemi M, Eriksson P O, Eriksson A, Thornell L E
Department of Clinical Oral Physiology, Umeå University, Sweden.
J Neurol Sci. 1998 Jan 21;154(1):35-48. doi: 10.1016/s0022-510x(97)00208-6.
The fibre composition of functionally different regions, the superficial and the deep portions, of the human masseter and the biceps brachii muscles of six elderly subjects (mean age 74 years) was studied by morphological and enzyme-histochemical methods. When compared to previous data for young adults, the masseter muscle from elderly subjects showed a significant decrease in the proportion of type I fibres and an increase of type IM and II fibre types, concomitant with muscle fibre atrophy. In the old biceps, there were no changes in the type I fibre proportion and fibre diameter, but a significant decrease in the type IIB fibre content. The present results of changes in fibre composition, in addition to previous findings of functional deterioration of the old masseter, probably reflect a combination of age related degenerative and adaptive processes within the trigeminal neuromuscular system. When compared with previous findings in young adult masseter, it can be concluded that the human masseter muscle differs from limb muscles both in fibre composition and in structural response of the muscle during aging. These differences between the masseter and the biceps brachii muscle suggest muscle specific alterations during aging probably due to differences in genetical control, functional performance and nerve and hormonal influences.
采用形态学和酶组织化学方法，对6名老年受试者（平均年龄74岁）的咬肌和肱二头肌功能不同区域（浅层和深层）的纤维组成进行了研究。与年轻人的先前数据相比，老年受试者的咬肌I型纤维比例显著降低，IM型和II型纤维类型增加，同时伴有肌纤维萎缩。在老年肱二头肌中，I型纤维比例和纤维直径没有变化，但IIB型纤维含量显著降低。除了先前关于老年咬肌功能退化的研究结果外，目前纤维组成变化的结果可能反映了三叉神经肌肉系统内与年龄相关的退行性和适应性过程的综合作用。与年轻人咬肌的先前研究结果相比，可以得出结论，人类咬肌在纤维组成和衰老过程中的肌肉结构反应方面均与肢体肌肉不同。咬肌和肱二头肌之间的这些差异表明，衰老过程中肌肉存在特定的改变，这可能是由于基因控制、功能表现以及神经和激素影响的差异所致。
