174 



THE STRUCTURE OF MAN 



. .th. 



would, therefore, be very interesting to follow closely, in Man's 

 development, the changes of position and inter -relationship 

 between the larynx and the upper part of the pharynx (choanse). 

 I am indebted to my colleague, Professor Killian, for knowledge 

 of the fact that the larynx of the human embryo may occupy 

 a high position, the upper edge of the epiglottis reaching even to 

 the uvula. 



The musculature of the human larynx appears to a great 

 extent to have been derived from the 

 simple sphincter and dilator appa- 

 ratus of lower Vertebrata, of Lizard- 

 like type. Under the more subtle 

 differentiation of the laryngeal 

 skeleton in Man, the musculature 

 has also undergone corresponding 

 changes for example, there is no 

 longer one single muscle for con- 

 stricting the glottis, but a whole 

 system of such muscles. In other 

 words, the reptile - like sphincter 

 laryngis has gained new points of 

 origin and insertion in the cartilage; 

 and Fiirbinger has proved that 

 while this is especially the case 

 with the deeper layers of the 

 sphincter, the superficial do not 

 undergo any such marked differ- 

 a greater extent the original condition, 

 tracts that the greater number of 



FIG. 102. HUMAN LARYNX IN 



FRONTAL SECTION. 

 th., thyroid cartilage ; -., cricoid car- 

 tilage ; tc., first tracheal cartilage ; 

 sn. } sinus of Morgagni. 



entiation, but retain to 

 It is in these superficial 

 variations are to be found. 



The close connection between the laryngeal and the pharyn- 

 geal musculature is evidenced not only by their common relation- 

 ships to the vagus nerve, but by the frequent occurrence of fibres 

 connecting the crico-thyroideus muscle with the constrictor 

 pharyngis inferior, i c^-^- 



Between the true and false vocal cords there arises on each 

 side of the larynx a diverticulum known as the ventriculus or 

 sinus of Morgagni (sn., Fig. 102). This evagination is directed 

 outwards and somewhat forwards ; it also projects upwards more 

 or less, and may even in rare instances reach the upper edge of 

 the thyroid cartilage. 



These Morgagni's pouches are susceptible of marked varia- 



