110 



NORMAL ANATOMY OF THE LARYNX. 



ligamentous fibres of the crico-arytenoid arti- 

 culation at B (Jig. 30) are relaxed ; for, al- 

 though some fibres lying nearest the mesial 

 plane are directed to draw the arytenoids to- 

 wards B, they are counteracted by the fibres 

 lying furthest from it, and by assuming the 

 whole to act together, the resultant will be as 

 nearly as possible perpendicular to the axis of 

 articulation O P, which would open the glottis ; 

 and therefore he concludes that the force of the 

 thyro-arytenoidei postici in a direction back- 

 wards may be neglected. Bichat erroneously 

 considered that they assist the thyro-aryte- 

 noidei and crico-arytenoidei in drawing the 

 thyro-arytenoid ligaments very tense.* 



The thyro-epiglottidei. These are a pair of 

 small muscles situated between the anterior sur- 

 face of the thyroid cartilage and epiglottis; they 

 arise from the internal surface of the thyroid 

 near its middle, and not far from the origin of 

 the thyro-arytenoidei ; their fibres are directed 

 upwards and forwards to the base of the epi- 

 glottis, to which they are inserted behind the 

 ligamenta thyro-epiglottidea. 



Their action is to depress the epiglottis. 



The aryteno-epiglottidei are two small mus- 

 cles, arising from the superior pyramid of the 

 arytenoid cartilages posterior to the arytenoid 

 muscles, or from the fibrous raphe situated 

 vertically behind them ; they pass upwards and 

 forwards to the sides of the epiglottis, and upon 

 the posterior border of the thyro-epiglottic 

 membrane. 



Action. Owing to the direction of their 

 fibres, the thyro- and aryteno-epiglottidei tend 

 to depress the epiglottis, or rather to effect the 

 tension of the aryteno-epiglottic mucous folds. 



The action of the intrinsic muscles of the 

 larynx may be briefly recapitulated as follows : 



The crico-arytenoidei postici open the glottis; 

 all the other muscles close it. 



The arytenoideus obliquus and arytenoideus 

 transversus approximate the arytenoid cartilages 

 posteriorly. The crico-arytenoidei laterales 

 and the thyro-arytenoidei bring them in contact 

 anteriorly. The thyro-arytenoidei close the 

 centre of the glottis, and with the crico-thyroidei, 

 assisted by the sterno-thyroidei, regulate the 

 tension, position, and vibrating length of the 

 chordae vocales. 



The crico-thyroidei and sterno-thyroidei an- 

 tagonise the thyro-arytenoidei, and in stretch- 

 ing the crico-thyroid ligament, the sterno-thy- 

 roidei with the thyro-arytenoidei antagonise the 

 crico-thyroidei. 



The crico-arytenoidei laterales, and thyro- 

 arytenoidei, and the arytenoideus obliquus and 

 transversus antagonise the crico-arytenoidei 

 postici. These last-named muscles likewise 

 may be said to antagonize all the muscles which 

 close the glottis. 



The genio-glossi, the linguales, the stylo- 

 pharyngei, and crico-pharyngei, and hyo-glossi, 

 are muscles associated in common with the mo- 



* Quand les thyro-arytenoidiens ot criro-arytc- 

 noidiens lateraux d'une part, et les crico-arytenoi- 

 diens postcricurs d'une autrc part agisscnt simul- 

 tancment. les ligamens thyro-arytenoidiens sont 

 fortcincnt icndus. 



tions of the tongue, pharynx, and larynx, and 

 belong rather to the structure and functions of 

 the two former of these organs than to the 

 larynx, and consequently are considered only 

 as auxiliary. 



The motions of the internal mechanism of 

 the larynx being effected by muscles, whose 

 forces are directed, with respect to each other, 

 in various degrees of obliquity, and in different 

 planes, and producing by their combination 

 results which can only be demonstrated on me- 

 chanical principles, it has been deemed desira- 

 ble to introduce them into the preceding inves- 

 tigations to insure greater precision of detail 

 and accuracy of result, and the more especially 

 as we find in the works of our best anatomical 

 writers the most discordant opinions, based ap- 

 parently upon mere hypothesis or superfical 

 observation, and without reference to any data 

 or principle from whence their conclusions are 

 drawn. 



The perusal of the works of Albinus,* IJal- 

 ler,f Cowper,| Sb'emmerino, Meckel,|| Bi- 

 chat,1T Magendie,** and Bell,ft confirm these 

 remarks ; exceptions to these observations are 

 found in the works of Borelli,}! Barthez, E. 

 and W. Weber,|||| Bernouilli,UH Barclay,*** 

 and Willis ;tff from the invaluable investiga- 

 tions of the latter much assistance has been de- 

 rived. 



Bloodvessels. The arteries of the larynx are 

 derived from the superior thyroid, a branch of the 

 external carotid and from the inferior thyroid, a 

 branch of the subclavian. Small veins accom- 

 pany the arteries and empty themselves into the 

 neighbouring trunks. 



Structures called glands. The arytenoid 

 gland. Syn. Glandulte. arytenoidece, Mor- 

 gagni, Bichat, Cloquet ; cnrtilugo cunei- 

 Jbrmis, Wrisberg, Bandt. The arytenoid 

 gland is an inappropriate designation given 

 to the cuneiform cartilage by Morgagni,|JJ; 

 whose views of the structure of this body are 

 adopted by Bichat, Cloquet,|||||| and Cru- 



* Historia Musculorum, lib. ii. chap. 2. 



t Elem. Pbys. torn. iii. 



j Anat. of the human body. 



De Corporis Hum. Struct. 



jj Traite Generate, torn. x. 



Tf Traite d'Anat. desc. torn. ii. 



** Physiol. 



ft Anat. of the human body. 



$} De motu animalium. Lugd. Batav. 1685. 



Nouvelle mechanique des mouvemens de 

 1'Homme et des Animaux, 1798. 



(HI Mechanik der Menschlichen Gehwerkzeuge, 

 mit xvii Taf Gbtt. 1836-8. 



1111 De motu musculorum. 



*** The muscular motions of the human body. 



ttt Cambridge Phil. Trans. 1833. 



tJJ Constant glandulae arytaenoidzpae ex granosa 

 substantial livido albescente, de qua utilem oblini- 

 endo laryngi succum maxime inter edenduin, aut 

 vociferandum, appressa epiglottis j vel conlracti 

 vicini musculi exprimunt. 



II apparoit que les deux glandes arytenoides 

 ne sont que des glandes muqueuses plus prononcees 

 que celles qui entourent le reste de la membrane 

 laryngee, mais qu'elles ont absolument le meme 

 usage. Op. cit. p. 386. 



Ullll Les glandes sont formees de petits grains 

 arrondis, assez consistans, d'une couleur grisatre. 

 Op. cit. 



