366 HEAD AND NECK 



the mucous membrane and the muscular fibres. The ducts 

 of these glands pierce the mucous membrane and open into 

 the vestibule. In each lip there is an arterial arch formed 

 by the corresponding labial arteries (p. 130). 



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 enter into the construction of the 

 cheeks, all of which have been examined in the dissection 



Frenulum linguae 

 Tip of tongue 



turned up _. - ^ ,._. , Plica fimbriata 



Deep lingual vein- >tms ^ _^,_ , . 



"'J lica sublmguau 



Orifice of 

 submaxillary duct 



FIG. 146. The Sublingual Region in the Interior of the Mouth. 



of the face, (i) Skin ; (2) a fatty layer traversed by some of 

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

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

 (5) numerous buccal glands, similar in character to the labial 

 glands, lie in the submucous tissue between the mucous mem- 

 brane and the buccinator muscle ; (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 aponeurosis, close 

 to the point where this is pierced by the parotid duct, and 

 their ducts open into the vestibule of the mouth. The 

 bucco-pharyngeal aponeurosis is a dense fascia which covers the 

 buccinator muscle. Above and below, it is attached to 



