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The histochemistry of reactive masticatory muscle hypertrophy
Author(s) -
Harriman Denis G.F.
Publication year - 1996
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/(sici)1097-4598(199611)19:11<1447::aid-mus9>3.0.co;2-c
Subject(s) - masticatory force , muscle hypertrophy , mastication , atrophy , medicine , muscles of mastication , endocrinology , anatomy , pathology , temporomandibular joint , orthodontics
There are two types of hypertrophy of the muscles of mastication in man: reactive hypertrophy, the more common form; and nonreactive enlargements—myositic, genetic, myopathic, and idiopathic. Reactive hypertrophy develops when the masticatory muscle workload is increased by local bone and dental disorders; such triggers are not powerful but act over long periods, thus demanding increased endurance. Exercise for endurance has a greater effect on the muscles of mastication than it has on the large muscles of the limbs; these react solely by stimulating the oxidative metabolism of type 1 fibers, whereas masticatory muscle reacts structurally by hypertrophy and progressive type 1 fiber predominance. Eventually enzyme instability of type 1 fibers and end stage atrophy of type 2 fibers may appear. Unexpectedly, lesions have also been found in control masticatory muscle, in particular type 2 fiber specific atrophy like that seen in long‐standing acquired autoimmune myasthenia gravis. It is suggested that the adverse lesions in hypertrophied and control masticatory muscle are the consequence of post‐activation fatigue. © 1996 John Wiley & Sons, Inc.