THE MOUTH. 



339 



Fiff. 150. 



ONE LOBE OF A RACE- 

 MOSE GLAND. 



t, Casing of connectiye 

 tissue; 2, Excretory- 

 duct ; 3, Glandxila]' 

 reside, or acini. 



The two genio-glossi lie together on the median plane of the tongue 

 except towards their origin, where they are constantly kept apart by adipose 

 tissue. Theii' inferior border responds to the genio-hyoid muscles, and their 

 anterior fibres are partly included between the two 

 mucous layers of the frssnum linguse. They are re- 

 lated, by their external face, to the basio- or great 

 hyo-glossus, the stylo-glossus, the sublingual gland, the 

 lingual artery, and the terminal branches of the three 

 lingual nerves. 



The action of the genio-glossus is complex ; accord- 

 ing to the portion of its fibres which contract, it will 

 carry the tongue forwards, pull it into the buccal 

 cavity, or draw it downwards into the floor of the mouth. 

 (Fig. 149, 4.) 



SMALL HTO-GLOSSUS. 



jnonym. — Lingualis superior of Man. {Lingualk of Perci- 

 vall.) 



Under this name is described a thin band, formed of 

 parallel fibres, which is exposed immediately on remov- 

 ing the mucous membrane, with the subjacent glands, 

 from the base of the tongue. This band arises from the 

 inner side of the articulation uniting the body of the os 

 hyoides to its small branch. It passes above the trans- 

 verse muscle of that bone, which it crosses perpendi- 

 cularly, is surrounded at this point by a great mass of 

 adipose tissue, and is prolonged directly forward, be- 

 neath the lingual mucous membrane. Its fibres then 

 vanish, either on the superior aspect of the tongue or 

 on its sides, or they descend obliquely in crossing the 

 direction of the hyo-glossus, to join the superior border 

 of the stylo-glossus (Fig. 149, 3). 



(This muscle contracts and retracts the tongue.) 



PHAEYKGO-GLOSSTJS. 

 (Synonym.— The palato-glosms of Man.) 



A rudimentary muscle formed of parallel fibres, 

 which, from their origin on the lateral wall of the 

 pharynx, pass outside the articular angle of the branches 

 of the OS hyoides, and between the hyo-glossus and genio- 

 glossus, mixing with, and intercrossing their fibres. 



3. Labial glands. — The numerous glands of the 

 tongue may be divided into racemose (or lobulated) 

 glands, and closed follicles (or follicular glands.) 



The racemose glands are spread on the sides and base 

 of the tongue. Near its upper border they form two 

 rows, which are rendered visible by the presence of a 

 small tubercle placed beside each of them. At the base 

 of the tongue they are found beneath the fungiform and 

 calyciform papillae, as well as beneath the layer of 

 inclosed follicles which lines the isthmus of the fauces. 



At the entrance to this passage, the Lngual mucous 

 membrane is mammillated, and each elevation has an 



FOLLIOULAE GLAND 



FROM THE ROOT OP 



THE TONGUE. 



1, Epithelium; 2, Pa- 

 piilseof mucous mem- 

 brane; 3, Cavity of 

 the follicle ; 4, In- 

 vesting coat of the 

 gland composed of 

 connective tissue ; 5, 

 Fibre - vascular ma- 

 trix, forming its par- 

 enchyma, and con- 

 taining, 6, 6, the 

 closed capsules or 

 follicles. 



