title: [Typologic characteristics of muscle fibers of the digastric muscle].
abstract: The digastric muscle has been studied in 6 men and in 14 rats. Succinic dehydrogenase (SDG) activity has been revealed, contents of muscle fibers of various types have been estimated, as well as areas of their cross sections. The number of capillaries around myons, their amount per 1 mm2 in the muscle cross section, volumetric fractions of the muscle fiber ultrastructures have been counted in the rats. In the anterior belly, that gets its motor innervation from the trigeminal nerve branches, the myons are larger, the SDG activity is lower, the number and density of the blood capillaries is less, in the fibers the sarcoplasmic reticulum is developed better and mitochondria are presented poorly. In the posterior belly, that is innervated by the fascial nerve motoneurons, the number of muscle fibers of the I type is greater than that of the II type. The differences in the myon composition of the bellies are rather connected with morphofunctional adaptation, that regulates quantitative signs of the structural organization of the muscle fibers, than with the source of innervation.
mesh_terms: D000328:Adult; D000818:Animals; D002196:Capillaries; D005154:Facial Nerve / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008410:Masticatory Muscles / Q000166:cytology* / Q000294:innervation; D008875:Middle Aged; D009132:Muscles / Q000648:ultrastructure; D051381:Rats; D013385:Succinate Dehydrogenase / Q000378:metabolism; D014276:Trigeminal Nerve / Q000502:physiology
chemical_list: D013385:Succinate Dehydrogenase
vernacular_title: Tipologicheskaia kharakteristika myshechnykh volokon dvubriushnoĭ myshtsy.