喉頭筋筋線維構成の比較解剖学的研究:3. イヌと霊長類, 筋線維と神経線維 COMPARISON STUDIES OF THE MYOFIBROUS ORGANIZATION OF LARYNGEAL MUSCLES:3. DOGS AND PRIMATES, MUSCLE FIBER AND NERVE FIBER
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発声と喉頭筋の発達との関係を明らかにするために, イヌ喉頭筋の筋線維構成を霊長類と比較するとともに, ヒトとサルの喉頭各筋の筋線維数と支配神経中の有髄神経線維数との比較を行い両者を対照し検討した.研究対象は, イヌは中等大の雑犬雌雄各1頭, ヒトは40歳代～50歳代の男性4名, サルはニホンザル雄成獣1頭で, イヌの喉頭筋はSudan Black B染色により筋線維を3型に分別, ヒトおよびサルの例では筋線維はHE染色, 神経線維はトルイジンブルー染色によった.結果: 1.イヌの喉頭筋には, ヒトおよびチンパンジーにみられた喉頭蓋筋と斜披裂筋は認められなかったが, 室筋が認められ, 発声への関与が考えられた.2.イヌの喉頭各筋の横断面積と筋線維総数は雌雄とも輪状甲状筋が最も大, 甲状披裂筋 (声帯筋を含む) がこれに次ぎ, 室筋が最も小で, 性別的には一般に雄の方が雌よりも大であったが, 横披裂筋と外側輪状披裂筋では差がなかった.3.イヌの喉頭各筋の筋線維型については, その頻度は各筋とも雄では白筋線維, 中間筋線維, 赤筋線維の順に高く, 雌の方が雄よりも白筋線維の頻度が高かった.その太さは, 雄では白筋線維, 中間筋線維, 赤筋線維の順に大で, 白筋線維は後輪状披裂筋と輪状甲状筋と横披裂筋が, 中間筋線維と赤筋線維では室筋が, それぞれ最も大で, 3筋線維型とも甲状披裂筋が最も小であった.雌でも雄と同順であったが, 中間筋線維と赤筋線維の差は少なかった.白筋線維では横披裂筋が最も大で雄と等しかったが, その他の筋では雄>雌の傾向が著明であった.4.イヌの喉頭各筋とヒト, チンパンジー, ニホンザル, ガラゴ等との比較では, チンパンジーに最も近く, ヒトよりも大きな筋が多く, 白筋的性格が強かった.5.ヒトとサルの喉頭各筋の支配神経中の有髄神経1に対する筋線維数を比較すると, ヒトの方がサルよりも各筋とも少なくて, 神経支配が密ということになり, その差は甲状披裂筋と横披裂筋において著明であった.ヒトとサルとイヌの喉頭各筋の筋線維総数をみると, ヒトとサルでは一定の数比が認められたが, ヒトとイヌとの問では筋によって大小の差が著しく, 異なった筋線維配分比を示していた.
The myofibrous organization of the laryngeal muscles of the dog was investigated and compared with those of macaque and man to elucidate relations between vocalization and laryngeal muscle morphology. In macaque and man, the innervation ratio of each laryngeal muscle was also analyzed. Materials and method : Materials included a male dog, a female dog, a male Japanese macaque and 4 male humans (ages in forties and fifties) . The dog laryngeal muscle fibers were stained with Sudan Black B and classified into three types. The laryngeal muscle fibers of the men and the macaque were stained with hametoxyline eosin and the nerve fibers were stained with toluidine blue. Results : 1. The laryngeal muscles of the dog did not include the musculus epiglotticus or arytenoideus obliquus which were observed in man and chimpanzee, but they did include the musculus ventricularis. 2. The cross sectional area and the total numbers of muscle fibers of the musculus cricothyroideus were the largest of the dog laryngeal muscles. Those of the musculus thyroarytenoideus including the musculus vocalis were the second largest, and those of the musculus ventricularis were smallest. Generally, all values were larger in male than in female. 3. The frequency of the white muscle fiber of each laryngeal muscle of the dog was highest and was followed by the intermediate muscle fiber. The female white muscle fiber frequency was higher than that of the male. Thickness of the muscle fibers decreased in the order of white, intermediate and red muscle fiber. The white muscle fibers of the musculi cricoarytenoideus dorsalis, cricothyroideus and arytenoideus transversus were larger. Although the order of the muscle fiber types in the female dog was same as that in the male, differences between the muscle fiber sizes of the intermediate and red muscle fiber were less than those of the male. The male muscle fibers tended to be larger. 4. Comparison of the laryngeal muscles of the dog with those of man, chimpanzee, Japanese macaque and galago revealed that the muscles of the chimpanzee were most similar to those of the dogs. Most of the laryngeal muscles of the dog were larger, and were more frequently white muscle fiber than those of men. 5. The ratios of muscle fibers per myelinated nerve fiber in man and macaque were compared. The ratios for all of the laryngeal muscles of man were smaller than those of macaques. Thus, a more dense ratio of innervation in man was concluded. The difference in this ratio was remarkable in the musculi thyroarytenoideus and arytenoideus transversus. Though the numbers of laryngeal muscles of man and macaque were similar, those of dog and man were much different, because of the remarkable differences in the numbers of each muscle.
- Journal of The Showa Medical Association
Journal of The Showa Medical Association 50(6), 591-599, 1990
The Showa University Society