434 HEAD AND NECK 



With the exception of the chondro-glossus, the extrinsic muscles have 

 been studied already, but the dissector should take this opportunity of 

 examining more fully their insertions, and the manner in which their fibres 

 are related to one another and to those of the intrinsic muscles. For this 

 purpose carefully reflect the mucous membrane from the right half of the 

 tongue, and follow the muscles into that side of the organ. At the same 

 time the lingual nerve and the profunda lingiue artery should be preserved. 

 On the under surface of the tongue, near the tip, the removal of the mucous 

 membrane will expose a group of glands, aggregated together so as to form 

 a small oval mass on each side of the median plane. This is known as the 

 apical gland or the gland of Niihn. 



The stylo-glossus will be seen running along the side of 

 the tongue to the tip, where the muscles of opposite sides 

 become to a certain extent continuous. The hyo-glossus 

 extends upwards to the side of the tongue, and its fibres pass, 



Palato-glossus 



Stylo-glossus 

 / Septum linguae 



'_ Inferior longitudinal 



muscle 

 Hyo-glossus 



Genio-glossus 



FIG. 171. Transverse section through the posterior part 

 of the Tongue. (From Gegenbaur.) 



for the most part, under cover of those of the stylo-glossus to 

 reach the dorsum, over the posterior part of which they spread 

 out, beneath the mucous membrane. The genio-glossus sends 

 its fibres vertically upwards into the tongue on each side of 

 the median septum, and its insertion stretches from the tip 

 to the base. The fibres of the palato-glossus become con- 

 tinuous with those which form the stratum transversum. 



The chondro-glossus is not always present. It is separated from the 

 deep surface of the hyo-glossus by the lingual vessels, and by the pharyn- 

 geal slip of the genio-glossus. It is a slender muscular band which takes 

 origin from the medial aspect of the root of the smaller cornu, and the 

 adjoining part of the body of the hyoid bone. Its fibres ascend, to enter 

 the tongue and finally spread out on the dorsum under cover of the 

 superior longitudinal muscle. 



Musculus Longitudinal is Superior. This is a continuous 

 layer of longitudinal fibres which covers the entire dorsum 

 linguae, from the root to the tip, immediately beneath the 

 mucous membrane. Towards the base of the tongue it is 



