178 



DISSECTION OF THE DOG 



Dissection. — Now turn to the dorsal part of the larynx. Remove the 



mucous membrane from the cricoid, arytenoid, and corniculate cartilages, 



taking care not to destroy the superior laryngeal and recurrent nerves 



and the connection between them. The origin of the longitudinal 



muscular fibres of the oesophagus from the median ridge of the cricoid 



lamina will be noted. The dorsal layer of the ary-epiglottic fold 



should be removed. Define the dorsal crico-arytenoid and arytenoid 



muscles. 



M. CRico-ARYTJENOiDEUS dorsalis. — The dorsal crico-arytenoid muscle 



arises from the dorsal surface and median ridge of the lamina of the cricoid 



cartilage. From this extensive origin the muscular fibres converge and are 



Cartilago comiculata s nK vcntricutaris 

 \ l 



n. laryngeus superior \ m. arytcenoideus transversus 



m. &ico-aryhvnoideus 

 dorsalis 



Cartilago epiglottica 



_n. recurrent 



Tracltea 



Os hyoidcum 



I 

 I 



ni. voccdis 



Cartilago cricoidea 

 in. crico-arytcenoideus latrralis 

 Cartilago thyreoidea 



Appendix ventriculi 

 laryngis 



Fig. 59. — Dissection of the larynx after removal of the lamina of the thyroid cartilage. 



inserted into the muscular process of the arytenoid cartilage. It follows 

 that all the fibres will not possess a like degree of obliquity, nor will they all 

 be of the same length. The more oral are the most nearly transverse and are 

 shortest ; the aboral fibres are longest and most nearly longitudinal ; whereas 

 the intermediate fibres are oblique. 



M. aryttenoideus.- — The arytenoid muscle of the dog is neither very 

 well developed nor very distinct. Its fibres arise from the arytenoid cartilage 

 in the region of the muscular process, and are inserted, along with the 

 bulk of the ventricular muscle, into the inter-arytenoid cartilage. Thus the 

 cartilaginous nodule forms a connection between the muscles of the two sides. 



Dissection. — The dissection of the remaining muscles should be confined, 

 for the time being, to one side of the larynx ; the other side being reserved 



