THE ALIMENTARY CANAL AND ITS APPENDAGES 443 



The Mouth- Cavity (Fig. 121) is bounded in front and on the 

 sides by the lips and cheeks, below by the tongue, k, and above 



by the palate; which latter consists 

 of an anterior part, Z, supported 

 by bone and called the hard palate, 

 and a posterior, /, containing no 

 bone, and called the soft palate. 

 The two can readily be distinguished 

 by applying the tip of the tongue 

 to the roof of the mouth and draw- 

 ing it backwards. The hard palate 

 forms the partition between the 

 mouth and nose. The soft palate 

 arches down over the back of the 

 mouth, hanging like a curtain be- 

 tween it and the pharynx, as can 

 be seen by holding the mouth open 

 in front of a looking-glass. From 

 the middle of its free border a 

 conical process, the uvula, hangs 

 down. 

 The Teeth. Immediately within 



FIG. 121. The mouth, nose and t h e cheeks and lips are two semi- 

 pharynx, with the commencement . r 



of the gullet and larynx, as exposed circles, formed by the borders of 



by a section, a little to the left of , , , , 



the median plane of the head, a, the upper and lower jaw-bones, 



vertebral column; b, gullet; c, wind- w V>ipVi QT-A Prv^Arprl KIT- tVA niivn* 



pipe; d, larynx; e, epiglottis, /, soft Wn] ' OVGI DV \ gums, 



palate; g, opening of Eustachian except at intervals along their edges 



tube; k, tongue; I, hard palate; m, . . 



the sphenoid bone on the base of where they contain sockets in which 

 ^iVca^y^^Tth^turWnaS the teeth are implanted. During 



bones of the outer side of the left Hf c two getg o f teet h are developed: 



nostril-chamber. 



the first or milk set appears soon 



after birth and is shed during childhood, when the second or 

 permanent set appears. 



The teeth differ in minor points from one another, but in each 

 three parts are distinguishable; one, seen in the mouth and called 

 the crown of the tooth; a second, embedded in the jaw-bone and 

 called the root or fang; and between the two, embraced by the edge 

 of the gum, is a narrowed portion, the neck or cervix. From dif- 

 ferences in their forms and uses the teeth are divided into incisors t 



