436 



VOICE. 



[CHAP. xxxi. 



as starting from the angle of the thyroid cartilage between the 

 insertions of the thyro-arytenoid muscles, whence the fibres radiate 

 downwards, obliquely backwards, and even somewhat upwards, 

 forming a continuous membrane which passes to the cricoid and 

 aryteiioid cartilages, lines the ventricles of the larynx, and is 

 connected with the crico-thyroid ligaments and the vocal chords, 

 both true and false. The thyro-hyoid ligament is likewise elastic ; 

 and also the fibrous bands which connect the epiglottis to the 

 thyroid cartilage and hyoid bone and the tongue. " If," says 

 Miiller, "we add to these parts the elastic longitudinal fibres in 

 the membranous part of the trachea and bronchi, we shall have 

 an idea of the great extent of the tissues susceptible of consensual 

 vibration and resonance in the parts surrounding the organ of 

 voice." * 



The mucous membrane of the larynx is part of the great respira- 

 tory tract, described at page 162, and possesses the same anatomical 

 characters at many points, being covered by ciliated epithelium. It 

 is involuted to a considerable extent, forming numerous glands 

 which cover the epiglottis, and are scattered over the interior 

 of the larynx. 



We have seen that the cricoid cartilage may move freely on the 



Pig, 212. thyroid, or vice versa ; and the 



arytenoids may be moved in 



c various directions on the upper 



border of the cricoid. More- 

 over, suspended, as it is, loosely 

 in front of the pharynx and 

 oesophagus, the whole apparatus 

 of the larynx may be moved 

 freely up and down in the 

 neck approximating, or reced- 

 ing from the lower jaw. For 

 these various movements the 

 larynx is provided with two 

 sets of muscles the extrinsic, 

 by which the whole organ is 



View of larynx from above, after Willis, b. Liga- n n , i , 



ments uniting arytenoid and cricoid cartilages, c. mOVCd, and tne intrinsic, 



and d. Direction of axis on which the thyroid cartilage T , T , i , ,1 



turns, e. Thyroid cartilage, k. Left thyro-arytenoid destined TO regulate 1116 mOVC- 

 muscle ; right removed. I, v, x. Cricoid cartilage. , f , -i 



m. Right crico-arytenoid muscle, n. Arytenoid car- HientS OI the VariOUS SCg- 

 tilages. o. Crico-arytenoidic-postici muscles, r. Pos- f 



terior part of cricoid cartilage, t, v. vocal ligaments. mentS. 



* Miiller's Physiology, by Baly, vol. ii., p. 1005. 



