THE TONGUE. 



883 



on the Hyo-glossus muscle in the submaxillary region, and from thence to the deep 

 glands of the neck. 



The nerves of the tongue are four in number in each half: the lingual branch 

 of the fifth, which is distributed to the papillae at the fore part and sides of the 

 tongue ; the lingual branch of the glosso-pharyngeal, which is distributed to the 

 mucous membrane at the base and side of the tongue and to the papillae circum- 



SubmaxiUary artery. 



Cartilage.^ 



Glosso- 

 phai-yngeal nerve. 



'Lingual artery. 



Superior laryngew 



FIG. 520. Under surface of the tongue, showing the distribution of nerves to this organ. (From a prepara- 

 tion in the Museum of the Royal College of Surgeons.) 



vallatse : the hypoglossal nerve, which is distributed to the muscular substance 

 of the tongue ; and the chorda tympani to the Lingualis muscle. Sympathetic 

 filaments also pass to the tongue from the nervi molles on the lingual and other 

 arteries supplying it. The glosso-pharyngeal branch is the special nerve of the 

 sense of taste, the lingual (gustatory) is the nerve of common sensation, and the 

 hypoglossal is the motor nerve of the tongue, except for the Inferior lingualis, 

 which is supplied by the chorda tympani. 



Surgical Anatomy. The diseases to which the tongue is liable are numerous, and its 

 surgical anatomy of importance, since an} 7 or all the structures of which it is composed muscles, 

 connective tissue, mucous membrane, glands, vessels, nerves, and lymphatics may be the seat 

 of morbid changes. It is not often the seat of congenital defects, though a few cases of vertical 

 cleft have been recorded, and it is occasionally, though much more rarely than is commonly sup- 

 pose*!, the seat of "tongue-tie," from shortness of the fra?num. (See page 554.) 



There is, however, one condition which must be regarded as congenital, though it does not 

 sometimes evidence itself until a year or two after birth, which is not uncommon. This is an 

 enlargement of the tongue which is due primarily to a dilatation of the lymph-channels and a 

 greatly increased development of the lymphatic tissue throughout the tongue. This is often 



