112 



NORMAL ANATOMY OF THE LARYNX. 



goes a sudden development, whilst in the female 

 it remains stationary. The comparative length of 

 the chink in the male and female is proportional 

 to the relative lengths of the vocal ligaments 

 already detailed. The length of the rima glot- 

 tidis bears no relation to the stature of the indi- 

 vidual. In the adult male it is about eleven 

 lines, of which the boundaries formed by the 

 arytenoid cartilages are four, and the thyro-ary- 

 tenoid ligaments seven lines. In the male and 

 female it is on a mean average as three in the 

 former to two in the latter. In a female, M. 

 Lauth however found the rima glottidis to mea- 

 sure from ten to eleven lines, whilst that of a 

 tall male extended only from eight to nine lines; 

 but this is a rare instance. 



The pomum Adami on the thyroid has a 

 corresponding concavity within, which affords 

 a greater length in the mesial section of the 

 larynx, and which tends to increase the longi- 

 tudinal dimensions of the glottis. In several 

 of the ruminantia the concavity is very con- 

 spicuous.* The breadth of the glottis is much 

 less than its length. In a state of repose its 

 transverse section is not more in the adult than 

 about two or three lines, or with respect to its 

 length as two to eleven, but the diameter varies 

 with the intensity of the forces of the intrinsic 

 muscles of the larynx. 



The ventricles. Ventricule ou sinus du larynx. 

 Cruv. These are oval or elliptical cavities 

 directed from before backwards, between the 

 superior and inferior ligaments. The depths of 

 the ventricles are effected by the distance from 

 the free margin of the vocal ligaments to the 

 internal surface of the thyroid, or rather to the 

 thyro-arytenoid muscles, which constitute the 

 bottom of the ventricles. The internal part of 

 the posterior cavity of the ventricles is enlarged 

 and deepened by a duplicature of the mucous 

 membrane passing external to the arytenoid 

 cartilage, which has been described by Mor- 

 gagni, and recently more particularly by Mr. 

 Hiltonf under the name sacculus laryngis. 

 The ventricles are prolonged anteriorly, extend- 

 ing along the vocal cords on each side of the 

 epiglottis. In size the ventricles vary with the 

 general dimensions of the larynx ; they are 

 each divided into an interior and posterior 

 cavity by a transverse ridge. The ventricles 

 afford greater freedom of motion to the inferior 

 thyro-arytenoid ligaments. 



Nerves. The larynx is exquisitely sensible, 

 and, as we have seen, combines complex and 

 delicate motions with secreting surfaces. These 

 properties result from its nervous endowment, 

 which is derived from two branches of the 

 pneumo-gastric nerve, namely, the superior 

 and the inferior laryngeal nerves. 



It will be unnecessary to enter into any de- 

 tailed description of these nerves here. Their 

 distribution will be found fully described in 

 the article PAR VAGUM, to which we refer. 

 Let it suffice to mention, that the superior la- 

 ryngeal nerve by its external branch gives fila- 

 ments, 1, to the inferior constrictor of the pha- 



* Vide Pallas Spicil. Zool. Trans, xii. 

 t Guy's Hosp. Reports, No. v. 



Fifr. 31. 



A view, from Mr. Swan, of the superior and 

 inferior laryngeal nerves. a, a portion of the 

 tongue ; b, the epiglottis ; c, the thyroid cartilage"; 

 d, the posterior arytenoid muscle divided for show- 

 ing a branch of the recurrent nerve passing to the 

 oblique and transverse muscles ; e, the lateral 

 crico-arytenoid muscle ; f, the thyro-arytenoid 

 muscle ; g, the arytenoideus obliquus ; h, the ary- 

 tenoideus transversus ; i, the crico-thyroid ; ;', 



1, the superior laryngeal nerve; 2, a branch of 

 this nerve to the membrane connected with that 

 covering the epiglottis ; 3, a branch of the superior 

 laryngeal to the membrane placed between the 

 superior extremities of the arytenoid cartilage ; 

 4, the recurrent nerve ; 5, a branch of the recur- 

 rent given off to the membrane lying between the 

 larynx and pharynx ; 6, a branch of the recurrent 

 nerve to communicate with a branch of the supe- 

 rior laryngeal nerve ; 7, a branch of the recurrent 

 to the posterior crico-arytenoid muscle ; 8, a branch 

 to the crico-thyroid and crico-arytenoid muscles ; 

 9, a branch giving filaments to the posterior crico- 

 arytenoid, and passing between this muscle and 

 the arytrnoid cartilage, to terminate in the oblique 

 and transverse arytenoid muscles. 



rynx; 2, to the thyro-hyoid muscle and mem- 

 brane ; 3, to the laryngeal plexus ; 4, to the 

 crico-thyroid muscle; 5, to the thyroid gland. 

 The internal branch of the superior laryngeal 

 nerve supplies filaments, 1, to the epiglottis; 



2, to the adipose and mucous membrane ; 



3, to the arytenoid muscles ; 4, to the thyro- 

 arytenoideus; .5, to the crico-arytenoideus late- 

 ralis; 6, a descending anastomotic branch to the 



