368 HEAD AND NECK 



more or less free in the buccal cavity, and there the mucous 

 membrane stretches across the floor from one side of the 

 mandible to the other. On each side in this region the 

 projection formed by the sublingual gland, the plica sublingualis, 

 can be distinguished. Further, if the tongue is pulled 

 upwards, a median fold of mucous membrane will be seen to 

 connect its under surface to the floor. This is the frenulum 

 lingua. At the sides of the frenulum the dissector must 

 look for the openings of the submaxillary ducts. Each 

 terminates on a papilla placed close to the side of the 

 frenulum. More posteriorly, between the side of the tongue 

 and the mandible and on the summit of the plica sub- 

 lingualis, are the openings of the sublingual ducts. 



Hoof of the Mouth. The hard and the soft palates form 

 the continuous concave and vaulted roof of the mouth (Fig. 

 149). Projecting from the middle of the posterior free margin 

 of the soft palate, and resting upon the dorsum of the tongue, 

 the uvula will be seen (Fig. 147). Running along the median 

 line of both the hard and the soft palates is a raphe 

 which terminates anteriorly, opposite the incisive foramen, 

 in a slight elevation or papilla termed the incisive papilla. 

 In the anterior part of the hard palate the mucous membrane, 

 on each side of the raphe, is thrown into three or four 

 transverse hard corrugations or ridges ; more posteriorly it is 

 comparatively smooth. By carefully palpating the postero- 

 lateral angles of the palate the dissector will be able to feel 

 the hamuli of the medial pterygoid laminae. 



Isthmus Faucium. This name is given to the communi- 

 cation between the mouth proper and the pharynx (Fig. 147). 

 To obtain a good view of it the mouth must be well opened 

 and the tongue depressed. The isthmus faucium and the 

 parts which bound it can be examined best in the living 

 subject (Fig. 147). It is bounded above by the soft palate, 

 below by the dorsum of the tongue, and on each side by two 

 curved folds of mucous membrane, termed respectively the 

 arcus glossopalatinus (O.T. anterior pillars of the fauces) and 

 the arcus pharyngopalatinus (O.T. posterior pillars of the 

 fauces). 



The arcus palatini spring from the base of the uvula, and 

 arch laterally and then downwards. The arcus glossopalatinus 

 inclines anteriorly as it descends ; it ends upon the side of 

 the posterior part of the tongue, and it encloses the glosso- 



