MUCOUS MEMBRANE OF THE MOUTH. 323 



especially at its back part. On the median line of the pal- 

 atine arch, the mucous membrane is most strongly attached 

 to the periosteum while on either side of this line there 

 is interposed a thick layer consisting of glands. These 

 glands are found to be sometimes disposed in regular rows 

 over the palatine arch, and from their being like the labial 

 and parotid, are called the palatine salivary glands. They 

 are in greater numbers behind than in front, and open by 

 many orifices which are visible to the eye. 



The mucous membrane, lining the cheeks, is a continua- 

 tion of that belonging to the lips, already described. There 

 is also, beneath it, a layer of glands of the salivary order, 

 which cause projections on its surface, and are called the 

 salivary buccal glands. They are precisely like the labial, 

 though smaller, and open by distinct orifices. Two of these 

 glands, from not being situated directly beneath the mem- 

 brane, but placed between the buccinator and masseter 

 muscles, are called the molar glands. Their ducts open 

 opposite the last molar tooth. 



The mucous membrane of the soft palate is remarkable 

 for its upper or nasal surface presenting the columnar 

 arrangement in its epithelium, while the lower or lingual 

 surface has the squamous form of the mouth. 



The mucous membrane of the pharynx has a reddish 

 appearance, and is characterized by its density and close 

 adhesion to the periosteum upon the basilar process. It 

 forms a rim around the mouth of the Eustachian tube, and 

 becomes thinner as it traverses the tube towards the cavity 

 of the tympanum. 



This relation established between the nose and throat, 

 and the Eustachian tubes, by the continuity of the same 

 mucous membrane into these several parts, is regarded as 

 the cause of that deafness which occurs from obstruction 

 in these tubes during coryza and chronic sore throat. 



Blood-vessels of the Houtli and Pharynx, (Fig. 73.) The 

 internal maxillary, facial, lingual, and pharyngeal arteries, 

 all branches of the external carotid, are the principal sources 

 whence the mouth and pharynx, with all their organs, are 



