HEAD. 



83 



ion: Elevator of the soft palate. Glands: situated 

 on the anterior face directly under the mucous mem- 

 brane. Mucous membranes : two in number, one on 

 the anterior and one on the posterior face. Blood ves- 

 sels, the pharyngeal and staphyline arteries. Nerves, 

 fifth pair of cranial nerves and ganglion of Meckel. 



y. Teeth. — Definition : passive organs of mastication. 



General characters: general disposition form two 

 parabolic arches interrupted on each side by interdental 

 space. These arches present the incisive teeth in front, 

 the tusks behind them, and the molars in the lateral 

 and posterior parts of the dental arches. External 

 conformation : they have a root or fang encased in an 

 alveolus, and a crown exposed. Structure : Ivory or 

 dentine forming the base of the tooth, and surrounds 

 the internal cavity wdiich is filled by the pulp ; it is 

 hollowed with canaliculi, imbeded in amorphous mat- 

 ter. Enamel forms the outside covering of the free 

 part of the tooth, consisting of little prismatic hexag- 

 onal rods denticulated on theii* faces. Cement irregu- 

 larly spread over both the ivory and enamel, with 

 the structure and properties of spongy bone-substance. 

 Dental pulp, fibrillar and nuclear mass filling the in- 

 ternal dental cavity, and receiving blood vessels and 

 nerves. The gum, a portion of the buccal mucous 

 membrane, surrounds the neck of the tootii. An 



