98 



TOPOGRAPHICAL ANATOMY OF THE 



sliould be noted. The lateral layer of the aryepiglottic fold of mucous 

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

 tlie transverse arytenoid muscles. 



M. CRICOARYT.ENOIDEUS DORSALTS. — The (lorsal crico-arjtenoid 

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

 lamina. From this extensive origin the muscular fibres converge and 

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

 follows that all the fibres will not have a like degree of obliquity, nor 



N. laryngeus cranialis. 



Corniculate cartilage, i 

 M. arytsenoideus transversus 

 I 

 M. cricoarytaenoideus dorsalis. 



A. thvreoidea cranialis 



Aryepiglottic fold. 



M. keratohyoideus. 



N. glossopharyngeus. 

 i Epiglottis. 



1 I A. lingualis. 

 1^- / Soft palate. 



I M. thyreohyoideus. 



j M. ventricularis. 



Thyroid lamina. 



Hvoid bone. 



Cricoid cartilage. 



M. cricothyreoideus. 



Fig. 37. — Lateral aspect of the larynx, 

 will they all be of the same length. The most anterior are the most 

 nearly transverse and are the shortest ; the posterior fibres are the 

 longest and most nearly longitudinal ; whereas the intermediate fibres 

 are oblique. The muscle rotates the arytenoid cartilage so that its 

 vocal process is carried away from the median plane, and thus the vocal 

 fold is abducted. 



M. ARYT^NOIDEUS TRANSVERSUS. — The transverse arytenoid 

 muscle is small and not very clearly defined. Its fibres spring from the 

 arytenoid cartilage in the region of its muscular process, and join a 

 tendinous raphe in the middle line that is common to fibres from both 

 sides of the larynx. Hence the muscle is generally described as 

 unpaired. In its action, the muscle draws the two arytenoid cartilages 



