156 



DISSECTION OF THE LARYNX. 



The ventricle of the larynx (fig. 42, A ) is best seen on the left side. It 

 is the oval hollow between the vocal cords, whose upper margin is semi- 

 lunar, and the lower straight. It is lined by the mucous membrane, and 

 on the outer surface are the fibres of the thyro-arytu-noid muscle. In the 

 anterior part is the aperture into the laryngeal pouch. 



The laryngeal pouch (sacculus laryngis) (fig. 42, D ), has been laid bare 

 in part on the right side by the removal of the half of the thyroid cartilage 

 (p. 153), but it will be seen again in the subsequent dissection for the 

 vocal cords. 



It is a small membranous sac, half an inch deep and cylindrical in form, 

 which projects upwards between the upper vocal cord and the thyroid 



slip of the depressor of the epiglottis, 



Fig. 42. and reaches sometimes as high as the 



upper border of the thyroid cartilage. 

 Its cavity communicates with the 

 front of the ventricle by a somewhat 

 narrow aperture. On the outer sur- 

 face are numerous small glands, 

 whose ducts are transmitted through 

 the coats of the sac to the inside. 

 Numerous nerves are distributed over 

 the top. Its upper part is covered by 

 the muscular slip before referred to. 



Dissection. The general shape and 

 position of the vocal cords are evi- 

 dent on the left half of the laryngeal 

 tube, but to show more fully the na- 

 ture of the lower cord, put the cut 

 surfaces in contact, and detach on the 

 right side the crico-arytrenoideus lat- 

 eralis from its cartilages. Remove 

 in like manner the thyro-arytasnoi- 

 deus, raising it from before back. By 

 the removal of the last muscle, a 

 fibrous membrane, crico-thyroid (fig. 

 44, 6 ), comes into view, and its up- 

 per free edge will be perceived to 

 constitute the inferior or true vocal 

 cord. AVhilst taking away the thyro- 

 aryta^noideus, the ventricle and the 

 sacculus laryngis, which are formed 

 chiefly by mucous membrane, will 

 disappear. 



The vocal cords or the tliyro-ary- 

 tcenoid ligaments (fig. 42), are two 

 bands on each side, which are ex- 

 tended from the angle of the thyroid 

 to the arytaenoid cartilage one form- 

 ing the upper, the other the lower 

 margin of the ventricle. 

 The nji/icr liyament (false vocal cord (fig. 42, ) is semilunar in form, 

 and is much weaker than the other. It is fixed in front to the angle of 

 the thyroid cartilage, near the attachment of the epiglottis ; and behind to 



VOCAL APPARATUS, ON A VERTICAL SECTION 

 OF THE LARYNX. 



A. Ventricle of the larynx. 



B. True vocal cord, 

 c. False vocal cord. 

 ]>. Sacculus laryugis 1 . 



E Arytaenoid cartilage. 



F. Cricoid cartilage. 



Q. Thyroid cartilage. 



ir. Epiglottis. 



K. Crico-thyroid ligament. 



L. Thyro-hyoid ligament. 



