ti8 SURGICAL APPLIED ANATOMY. [i:iv.p. vm. 



the pus may escape along the groove of the fang. 

 With other teeth the pus tends to pierce the alveolus, 

 If the point of the fang is within the reflection of the 

 mucous membrane from the gum to the cheek the 

 abscess will break into the mouth, but if the point of 

 the fang is without that reflection, or if the pus can 

 gravitate without the line of the reflection, then the 

 pus may break through the cheek. Alveolar abscess 

 of the upper incisors and canines never breaks through 

 the cheek. When connected with the upper molars it 

 sometimes does. When connected with any of the 

 lower teeth the abscess may find its way through the 

 skin of the cheek. 



CHAPTER VIII. 



THE MOUTH, TONGUE, PALATE, AND PHARYNX. 



THE lips. The principal tissues composing the 

 lips have the following relation to one another pro- 

 ceeding from without inwards: (1) Skin; (2) super- 

 ficial fascia; (3) orbicularis oris ; (4) coronary vessels; 

 (5) mucous glands ; and (6) mucous membrane. The 

 free border of the lip is very sensitive, many of the 

 nerves having end bulbs closely resembling tactile 

 corpuscles. The upper lip is supplied with sensation 

 by the second division of the fifth nerve, and the lower 

 lip by the third division. Over these labial nerves a 

 crop of herpes often appears (herpes labialis). The 

 free border of the lower lip is more frequently the seat 

 of epithelioina than is any other part of the body. 

 The lips contain a good deal of connective tissue, and 

 may swell to a considerable size when inflamed, or 

 cedematous. They are very mobile, and are entirely 

 free for a considerable extent from bony attachment 

 of any kind. It follows that destructive inflamma- 

 mutions of the lips, and such losses of substance as 

 accompany severe burns, produce much contraction 



