332 HEAD AND NECK 



short and nearly horizontal ; the intermediate fibres are the 

 longest, and are very oblique; whilst the lowest fibres are 

 almost vertical in their direction. The posterior crico- 

 arytsenoid muscles are abductors of the vocal folds. They 

 are supplied by the inferior laryngeal nerves. 



Musculus Arytaenoideus. The arytasnoid muscle consists 

 of two portions a superficial part, termed the arytcenoideus 

 obliquus, and a deeper layer, called the arytcenoidens transversus. 



Epiglottis' 

 Lesser cornu of hyoid bone 



Body of hyoid bone - 



Lamina of thyreoid f 



cartilage r 



Musculus vocalis 



M. cricoarytaenoideus lateralis 



M. cricoarytsenoideus posterior 



Crico-thyreoid ligament 



Trachea .. 



FIG. 124. Side view of the Muscles of the Larynx. The fibres passing 

 backwards and upwards from the upper border of the musculus vocalis 

 are the fibres of the thyreo-epiglotticus. They blend above with the 

 ary-epiglotticus. 



The aryt&noideus obliquus is composed of two bundles of 

 muscular fibres, each of which springs from the posterior aspect 

 of the muscular process of the corresponding arytgenoid 

 cartilage (Fig. 123). From those points the two fleshy slips 

 proceed upwards and medially, and cross each other in the 

 median plane like the limbs of the letter X. Some of the 

 fibres are inserted into the summit of the arytsenoid car- 

 tilage of the opposite side, but the greater proportion 

 are prolonged, round the base of the corniculate cartilage, 



