Anatomy and Physiology of the Larynx. 85 



heart) and bloodvessels, as well as lymphatic glands, but 

 also in its greater length. The influence of these anatomical 

 peculiarities in the production of Roaring will be fully dealt 

 with hereafter. 



Bischoff, Schech, Chauveau (for the horse), and others, 

 have shown that the spinal accessory nerve gives motor 

 fibres to the recurrent nerve, which would go to prove that 

 the two nerves are identical in their function, a circumstance 

 which should also be remembered in discussing the origin 

 of Roaring. 



The Larynx as a Whole. 



Having considered the different parts of the larynx, we 

 may now view it as a whole. 



We have remarked that it is placed between the branches 

 of the lower jaw, towards their angle, at the upper part of 

 the windpipe, and the back part of the mouth or pharynx, 

 its upper opening looking into that cavity, in which it is 

 suspended from the base of the cranium by the long pro- 

 cesses or horns of the hyoid bone. Immediately behind or 

 above it is the cesophagus, which is attached to the middle 

 ridge on the bezel of the cricoid cartilage. 



The cavity of the larynx (cavum laryngis) is described 

 as divided into three spaces or portions — upper, lower, and 

 middle ; it opens into the floor of the pharyngeal sac by its 

 upper space or supra-glottic portion (aditus ad laryngeum, 

 introitus laryngis, Figs. 1, 3). This large opening is in shape 

 that of an equilateral triangle (Fig. l,g), the base being the 

 epiglottis in front, while the apex is formed by the two ary- 

 tffinoid cartilages, and the sides by the ary-epiglottic folds 

 of mucous membrane {plicm ary-epiglotticce). It must be 

 noted that the form and dimensions of the larynx often 

 difier considerably, even in animals of the same size. In 

 a medium-sized horse, the length of this triangular space 

 in the passive condition is from If to 2 J inches, and width 

 of base li to 1^ inch. Its depth is about 1^ inch. The 



