title: Muscle fiber types in the cat middle ear muscles. II. Tensor tympani.
abstract: Using quantitative histochemical techniques, it was determined that the tensor tympani muscle of the cat consists of three muscle fiber types: type 1, type 2A (staining characteristics similar to the type 1 and type 2A muscle fibers found in the control tibialis anterior muscles), and a third unclassified fiber type (type 3) similar to the 2A fiber type except that it had extremely dense alkaline actomyosin adenosine triphosphatase staining (mean transmittance, type 2A = 33.6%; type 3 = 17.3%), as well as dense staining for periodic acid-Schiff, menadione-linked alpha-glycerolphosphate dehydrogenase, nicotinamide-adenine dinucleotide tetrazolium reductase, and succinic dehydrogenase. The type 1 fiber population was smaller in diameter (mean +/- SD, 14 +/- 4 microns) than the type 2A fiber (mean +/- SD, 21 +/- 5 microns) and the type 3 fiber (mean +/- SD, 22 +/- 6 microns) populations. In all muscles, intrafascicular and extrafascicular fat accumulations were found, with the majority being extrafascicular. Calculations indicate that the tendon occupies approximately 41% of the total muscle volume, while the muscle fibers constitute 59% of the volume.
authors.affiliation: Department of Otolaryngology and Communication Sciences, State University of New York Health Science Center, Syracuse 13210.
authors.forename: M J
authors.initials: MJ
authors.lastname: Lyon
authors.forename: L T
authors.initials: LT
authors.lastname: Malmgren
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis; D000818:Animals; D002415:Cats / Q000033:anatomy & histology*; D006651:Histocytochemistry; D009119:Muscle Contraction; D013710:Tendons / Q000033:anatomy & histology; D013719:Tensor Tympani / Q000033:anatomy & histology* / Q000201:enzymology / Q000502:physiology; D014432:Tympanic Membrane / Q000033:anatomy & histology*
chemical_list: D000251:Adenosine Triphosphatases