An American text-book of physiology . the vocal cordsarc made toise by contraction of thecrico-thyroids; the vocal cords arc slack-ened by the combined action of thesphincter group and especially by theexternal thyro-arytenoids. It will easily be seen that in thelarynx, as in the skeleton at large, theefficiency of any single nmscle involvesthe action of accessory uniscles; thus,contraction of the crico-thyroid couldhave little effect in tightening the vocalcords were not the arytent)id cartilagesfixed by contraction of the posterior crico-arytenoid and arytenoid of the
An American text-book of physiology . the vocal cordsarc made toise by contraction of thecrico-thyroids; the vocal cords arc slack-ened by the combined action of thesphincter group and especially by theexternal thyro-arytenoids. It will easily be seen that in thelarynx, as in the skeleton at large, theefficiency of any single nmscle involvesthe action of accessory uniscles; thus,contraction of the crico-thyroid couldhave little effect in tightening the vocalcords were not the arytent)id cartilagesfixed by contraction of the posterior crico-arytenoid and arytenoid of the Larynx.—The larynx receives its nerve-sui>])ly fromthe superior and the inferior or recurrent laryngeal nerves. The extremelyscnisitive surface of the mucous membrane of the organ above the vocal cordsis supplied by sensory filaments of the superior laryngeal nerve. The superiorlaryngeal also supplies motor fibres to the crico-thyroid muscle, whose actionas a tightener of the vocal cords is peculiar. All the other muscles of the. Fig. 301.—Diagram to illustrate the thyro-aryte-noid muscles; the figure represents a transversesection of the larynx through the bases of thearytenoid cartilages (redrawn from Foster): Ary,arytenoid cartilage: , processus nuiscularis;, processus vocalis: TTi, thyroid cartilage; ;,vocal cords; (E is placed in the cesophagus;, internal thyro-arytenoid muscle;, external thyro-arytenoid muscle;, part of the thyro-ary-epiglottic mus-cle, cut more or less transversely; , trans-verse arvtenoid muscle. VOICE AND SPEECH. 869 larynx receive tlioir motor impulsos iVoiii the inferior larvnt^otil nerve. Muchof the nervous mechanism of the larynx is still in dispute. Laryngoscopic Appearance of the Larynx.—Much may be learned hyinspection of the larvnx dnrinji; life hy means <tf tli< larynj^oscopic mirror. Itis not difficult for an observer to examine his own larynx by placing himselfbefore a second mirr
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Keywords: ., bookautho, bookcentury1800, bookdecade1890, booksubjectphysiology
