406 



THE DIGESTIVE APPARATUS IN MAMMALIA. 



the sublingual gland, the lingual artery, and the terminal branches of the three 

 lingual nerves. 



The action of the genio-glossus is complex ; according 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. 



Small Hyo-glossus (Lingualis) (Fig. 220, 3). 



Synonym. — Lingualia superior of Man. 



Under this name is described a thin band, formed of parallel fibres, which is 

 exposed immediately on removing 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 cornu. It passes 



Fig. 222. 



Fig. 221. 



ONE LOBE OF A RACE- 

 MOSE GLAND. FOLLICULAR GLAND FROM THE ROOT OF THE 

 1, Envelope of connec- tongue. 



tive tissue; 2 excre- j^ Epithelium; 2, papilla of mucous mem- 



tory duct ; 3, glandu- ^rane ; 3, cavity of the follicle ; 4, invest- 



lar vesicle, or acini. j^g ^^s^t of the gland composed of connective 



tissue ; 5, fibro-vascular matrix, forming its 



parenchyma, and containing, 6, 6, the 



closed capsules or follicles. 



above the transverse muscle of that bone, which it crosses perpendicularly, is 

 surrounded at this point by a great mass of adipose tissue, and is prolonged 

 directly forward, beneath 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. 



(This muscle contracts and retracts the tongue.) 



Pharyngo-glossus (Palato-glossus) (Fig. 220, 5). 



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). 



