174 THE STRUCTURE OF MAN 
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 (choane). 
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- 
lke type. Under the more subtle 
differentiation of the laryngeal 
skeleton in Man, the musculature 
‘has also undergone corresponding 
changes—tfor 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- lke sphincter 
laryngis has gained new points of 
origin and insertion in the cartilage; 
and Fiirbinger has proved that 
Fic. 102.—Human Larynx IN 5 aes : 
TNT Sore while this is especially the case 
th., thyroid cartilage ; cr., cricoid car- with the deeper layers of the 
Bee er ee ea cartilage; sphincter, the superficial do not 
: undergo any such marked differ- 
entiation, but retain to a greater extent the original condition. 
It is in these superficial tracts that the greater number of 
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- thyroid muscle with the constrictor 
pharyngis inferior. 
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.(sv., 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- 
