THE SALIVARY GLAXDS. 33o 



portion of its mucous membrane, as well as that of the free margin of 

 the velum, is covered with scaly, stratified epithelium ; but quite at its 

 upper portion, near the orifice of the Eustachian tul3e, the epithelium is 

 columnar and ciliated. In the new-born child the whole posterior sur- 

 face is covered with ciliated epithelium (Klein), but this becomes sub- 

 sequently replaced by squamous ; the epithelium of the gland-ducts, 

 however, retains in many instances its ciliated character. 



On both surfaces of the velum are found numerous small compound 

 glands, called the imlatine glands. They particularly abound on the 

 upper surface, where, they form almost a complete layer under the 

 mucous membrane ; they are also very abundant in the uvula. 



THE TONSILS. 



The tonsils (tonsillar, amygdalae) are two prominent bodies, which 

 occupy the recesses formed, one on each side of the fauces, between the 

 anterior and posterior palatine arches and the pillars of the fauces 

 (fig. 235, /). 



They are usually about half an inch in length, and a third in width 

 and thickness ; but they vary much in size in different individuals. 



The outer side of the tonsil is connected with the inner surface of 

 the superior constrictor of the pharynx, and approaches very near to 

 the internal carotid artery. Considered in relation to the surface of 

 the neck, the tonsil corresponds to the angle of the lower jaw, where it 

 2nay be felt beneath the skin when it is enlarged. Its inner surface, 

 projectiug into the fauces between the palatine arches, presents from 

 twelve to fifteen orifices, which give it a perforated appearance. These 

 orifices lead into recesses or crypts in the substance of the tonsil, 

 like those already described (pp. 330-1) as occurriug at the back part 

 of the upper surface of the tongue. The tonsils contain a large amount 

 of lymphoid tissue ; indeed this appears to constitute their main 

 substance. 



These structures receive a very large supply of blood from various arteiies. 

 viz., from the tonsillar and i^alatine branches of the facial arteiy, and from the 

 descending palatine, the ascending pharyngeal and the dorsalis lingute. From 

 these arteries fine branches and capillaries are distributed abundantly to the 

 lymphoid tissue and follicles and to the papilla3 of the mucous membrane which 

 lines the recesses. The veins are numerous, and enter the tonsillar plexus on its 

 outer side. The nei-ves come from the glosso-pharyngeal nerve, and from the 

 fifth pair. Lymphatics are abundant, and, as in the pliarynx. are collected into 

 a deep and superficial layer. 



THE SALIVARY GLANDS. 



The saliva, which is poured into the mouth, and there mixed with 

 the food during mastication, is secreted by three pairs of glands, named 

 from their respective situations, parotid, suhmaxillary, and sullingual. 

 Agreeing in their general physical characters and minute structure, 

 these glands differ in their size, form, and position. 



THE PAROTID GLAND. 



The parotid (fig. 236, p) is the largest of the three salivary glands. 

 It lies on the side of the face, in front of the ear, and extends deeply 

 into the space behind the ramus of the lower jaw. Its weight varies 

 from five to eight drachms. 



Its outer surface is convex and lobulated, and is covered bv the skin 



