THE HUMAN MOUTH
Materials:Amirror.
Follow thisprocedure: Openyourmouthwide and examineyourteeth.
Noticeespeciallytheirdifferent shapesand theirpositions in the upperand
lowerjaws.
Feel the insideofyourcheeksonbothsides withyourtongue(justopposite
the second uppermolar). Youwill feel a slight bumpon each side anda
liquidwill flowontoyourtongue.
Nowfeel the roofofyourmouth with yourtongue. Lookat it in the
mirror. Examineyourtonguein the mirror,too. Roll itaround. Withyour
tongue,feel the lowersurfaceofyourmouthunderthetongue. Lookat this
sectionin themirror.
You will observe: Youhavefouressentiallydifferentkindsofteeth. The
fourfrontteeth in boththeupperandlowerjawsare squarewithknife-like
orchisel-shapededges. Theseare calledincisors. Oneachsideoftheincisors
are single, pointedteeth. Thesearecommonlyknownas"eye"teethbecause
theyareunderthe eyes,butthey are officiallycalledcanines.
Nextto thecaninesarelargerteethwith hill-likeprojectionscalledcusps
on theirsurface. Theseare yourmolars.
By the time you are 8 or 9 years old, you willprobablyfind 24teethin
your mouth. Between the ages of 18 and24 you may develop additional
molarscalled"wisdomteeth."
Theslightbumpsyou feltwhenyoupassedyourtongueacrosstheinsides
ofyourcheeks are the openingsintoglandscalledthe salivaryglands. The