MOUTH 279 



The lymph vessels of both lips join the submaxillary 

 lymph glands, but some of the lymph vessels of the upper 

 lip pass to the superficial parotid glands. 



Buccse. Six layers can be distinguished in the cheeks, 

 four of which were examined in the dissection of the face. 

 They are (i) Skin; (2) a fatty layer, traversed by some of 

 the facial muscles and by the external maxillary artery; (3) 

 the bucco-pharyngeal fascia ; (4) the buccinator muscle ; 

 (5) the submucous tissue, in which lie numerous buccal glands 

 similar in character to the labial glands; (6) the mucous 

 membrane. Four or five mucous glands of larger size, 

 termed the molar glands, occupy a more superficial position. 

 They lie either external or internal to the bucco-pharyngeal 

 fascia, close to the point where it is pierced by the parotid 

 duct, and their ducts open into the vestibule of the mouth. 

 The bucco-pharyngeal fascia is a dense membrane which covers 

 the buccinator muscle. Above and below, it is attached to 

 the alveolar portions of the maxilla and mandible respectively, 

 whilst posteriorly it is continued over the pharynx. The 

 muscles which traverse the fatty layer are chiefly the zygo- 

 maticus, the risorius, and the posterior fibres of the platysma. 

 The parotid duct pierces the inner four layers of the cheek, 

 and opens into the vestibule of the mouth, opposite the second 

 molar tooth of the maxilla, 



Gingivse et Dentes. The gums are covered with a smooth 

 and vascular mucous membrane, which is firmly bound down 

 to the subjacent periosteum of the alveolar portions of the 

 jaws by a stratum of dense connective tissue. It is continuous, 

 on the one hand, with the mucous membrane of the lips and 

 cheeks, and, on the other, with the mucous membrane of the 

 mouth proper. The gums closely embrace the necks of the 

 teeth. 



In the adult, the teeth in each jaw number sixteen. From 

 the median line backwards, on each side, they are the two 

 incisors, the canine, the two praemolars, the three molars. 



Floor of the Mouth. The mucous membrane is reflected 

 from the inner aspect of the mandible to the side of the 

 tongue ; but in the anterior part of the mouth the tongue lies 

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

 membrane stretches across the floor from one half of the 

 mandible to the other. On each side, in the anterior region, 

 the projection formed by the sublingual gland, the plica sub- 



