ioo SURGICAL APPLIED ANATOMY. [Chap. vm. 



division of the fifth), and who developed a patch of 

 gray hair over the region supplied by the auriculo- 

 temporal nerve (a branch also of the third division). 



The muscles of mastication are often attacked 

 by spasm. When the spasm is clonic the chattering 

 of the teeth is produced that is so conspicuous a 

 feature in rigor. When the spasm is tonic the mouth 

 is rigidly closed, and the condition known as trismus, 

 or lockjaw, is produced. Trismus is among the 

 first symptoms of tetanus. It is also very apt to be 

 produced by irritation of any of the sensory branches 

 of the third division of the fifth, since the motor nerve- 

 supply of the muscles themselves is derived from that 

 trunk. Thus trismus is very common in caries of the 

 lower teeth, and during the " cutting " of the lower 

 wisdom tooth. It is much less common in affections 

 of the upper set of teeth, since they are supplied by 

 a more remote division of the fifth nerve. 



CHAPTER Till. 



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, Tke rppsr li'p* ?V Supplied with 

 sensation "by ^ the secohd* division <)$' the- 'fifth nerve, 

 and the idwer lip by the "third division. Over these 

 labial -nerv?^ ?, crop of herpes often appears (herpes 



