Anatomy and fiber type composition of human interarytenoid muscle.
Intrinsic laryngeal muscle investigations, especially those of the interarytenoid (IA) muscle, have been primarily teleologically based. We determined IA muscle anatomy and histochemical and immunohistochemical classification of extrafusal and intrafusal (muscle spindle) fibers in 5 patients. Extrafusal fibers were oxidative type I and glycolytic types IIA and IIX. Intrafusal fibers of muscle spindles were identified by the presence of tonic and neonatal myosin. The results demonstrate that the IA muscle has a phenotype similar to that of limb skeletal muscle. Myosin coexpression, the absence of intrafusal fibers, and fiber type grouping were unusual features found previously in the thyroarytenoid and posterior cricoarytenoid muscles, but they were not present in the IA muscle. These findings lead to the conclusion that the IA muscle has functional significance beyond its assumed importance in maintaining vocal fold position during phonation. The presence of spindles demonstrates differences in motor control as compared to the thyroarytenoid and posterior cricoarytenoid muscles. Further, extrafusal fiber characteristics implicate IA muscle involvement in muscle tension dysphonia and adductor spasmodic dysphonia. Given the unique physiologic characteristics of the human IA muscle, further research into the role of the IA muscle in voice disorders is warranted.
Department of Communication Science and Disorders, University of Pittsburgh, Pennsylvania, USA.
Cari M
CM
Tellis
Clark
C
Rosen
Apurva
A
Thekdi
James J
JJ
Sciote
D000255:Adenosine Triphosphate / Q000378:metabolism; D000368:Aged; D000906:Antibodies / Q000032:analysis; D001193:Arytenoid Cartilage / Q000033:anatomy & histology; D002237:Carbohydrate Dehydrogenases / Q000032:analysis; D005260:Female; D050536:Glycerol-3-Phosphate Dehydrogenase (NAD+); D005993:Glycerolphosphate Dehydrogenase / Q000032:analysis; D006801:Humans; D007150:Immunohistochemistry; D007821:Laryngeal Muscles / Q000033:anatomy & histology* / Q000166:cytology / Q000294:innervation / Q000378:metabolism; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000145:classification* / Q000378:metabolism / Q000648:ultrastructure; D009470:Muscle Spindles / Q000033:anatomy & histology / Q000378:metabolism; D009210:Myofibrils / Q000201:enzymology; D018995:Myosin Heavy Chains / Q000276:immunology / Q000378:metabolism; D013194:Staining and Labeling
D000906:Antibodies; D000255:Adenosine Triphosphate; D002237:Carbohydrate Dehydrogenases; D005993:Glycerolphosphate Dehydrogenase; D050536:Glycerol-3-Phosphate Dehydrogenase (NAD+); C104557:sorbose dehydrogenase; D018995:Myosin Heavy Chains