IOO 



Life and Health 



thus being crushed it is moved to and fro by the varied 



movements of the tongue, so that every part of it may be 



mixed with saliva. 



151. The Teeth. The teeth are attached to the upper and 



lower maxillary bones by roots contained in sockets in the 



jaws. Each tooth 

 consists of a 

 crown, the visible 

 part, and one or 

 more fangs, buried 

 in the sockets. 

 There are in 

 adults thirty-two 

 teeth, sixteen in 

 each jaw. 



Teeth differ in 

 name according 

 to their form and 

 the uses to which 

 they are specially 

 adapted. Thus, at 

 the front of the 

 jaws there are 

 incisors, or 'cutting 

 teeth, two on each 

 side. The incisors 



FiG. 45. Cavities of the Mouth, Pharynx, etc. 

 (Section in the middle line designed to show the mouth 



in its relations to the nasal fossae, the pharynx, and 



the larynx.) 

 A, sphenoidal sinus ; , internal orifice of Eustachian 



tube; C, velum palati; D, anterior pillar of soft 



palate ; , posterior pillar of soft palate ; F, tonsil ; 



//, lingual portion of the pharynx ; K, lower portion 



of the pharynx; L, larynx; Af, section of- hyoid 



bone ; N, epiglottis ; O, palatine arch. 



divide the food 

 and are well devel- 

 oped in rodents, as squirrels, rats, and beavers. 



Next come the canines, or cuspids, two in each jaw, 

 so called from their resemblance to the teeth of dogs and 

 other flesh-eating animals. The upper two are often called 

 eye teeth, and the lower two, stomach teeth. 



