'298 ANATOMICAL TECUNOLOGY. 



ter (§ 362). If the abdomen is not to be used (§ 234), it is easier to 

 inject from the postcava and the aorta (§§ 363, 365). 



As plaster will not pass the valves in the veins, it is best for this 

 preparation, as for Fig. 101, to inject the jugular vein with fine blue 

 mass (see § 1450) instead of blue plaster. This is only necessary, 

 however, for permanent preparations or for special demonstrations. 



§ 773. Salivary Glands.— The salivary glands are the organs, 

 belonging to the digestive system, whicli secrete the saliva and pom- 

 it into the oral cavity through single or multiple ducts. They are 

 situated in close proximity to the mouth and mostly just entad of 

 the skin. There are 5 on each side : — Parotid, submaxillary, sub- 

 lingual, molar, zygomatic. 



§ 774. Preparation of the Ducts of the Salivary Glands. — 

 These should be injected with Berlin blue (see § 1449), or if that is 

 not at hand, there may be used a sufficient quantity of chrome 

 green or orange ground in 15 per cent, glycerin to give a decided 

 color. As the process of injection is somewhat troublesome, the 

 ducts may be demonstrated by inserting into them beaded bristles. 



§ 775. Preparation of WTiartorC s Duct. — This opens on the 

 summit of a prominent papilla situated in the floor of the mouth 

 just cephalad of the frsenum (Fig. 88). It usually lies on the floor 

 of the mouth. Grasp it near its free end with the fine forceps, and 

 enlarge the ojDening with the probe of the tracer ; then insert a 

 beaded bristle or the canula for injection (§ 358). 



Injection. — The canula need not be tied, but merely compressed 

 with the fingers while injecting. Before commencing the injection, 

 the canula should be filled with the injecting mass to avoid air. In 

 making the injection, the pressure should be light and continued for 

 but a short time lest the duct be ruptured. If the injection is suc- 

 cessful and the tongue be turned to the opposite side, the duct may 

 be seen in the floor of the mouth extending nearly parallel with the 

 mandibular ramus as far caudad as the last tooth. 



§ 776. Preparation of Stenon^s Duct. — With coarse forceps or 

 the fingers, grasp the dorsal lip near the angle of the mouth and 

 draw it laterad so as to expose the mucous membrane opposite the 

 last pra3molar tooth (Fig. 61). Just cephalad of the angle of the 

 mouth and opposite the most prominent cusp of the last prsemolar 

 will be seen a slight ridge on the mucous membrane. The cephalic 

 end of this ridge is about 1 cm. from the edge of the lip, and at the 

 end will be seen a slight circular depression, wliich is the opening 



