THE BUCCAL CAVITY. 15 
the dorsal surface of the head, close to its 
anterior end. 
B, The Buccal Cavity. 
Open the mouth to its full extent: note the wide buccal or mouth 
cavity, of which the hinder part or pharynx is continued back into 
the esophagus. Note also the following structures -— 
1. On the Roof of the Mouth. 
a. Teeth. 
i, Maxillary teeth; a row of fine teeth attached 
round the edge of the upper jaw. 
ii, Vomerine teeth: two small patches of sharp teeth 
in the fore part of the roof of the mouth and 
near the middle line. 
b, The posterior nares. Two small holes lying to the 
outer sides of and slightly in front of the two patches 
of vomerine teeth. 
_ Pass bristles through the nostrils, and see that they 
come out through the posterior nares into the buccal 
cavity. 3 
c. The Eustachian tubes or recesses. A pair of much 
larger holes at the sides of the posterior part of the 
buccal cavity. Each hole opens into a slightly 
dilated chamber—the tympanic cavity—which is 
closed externally by the tympanic membrane already 
seen on the surface of the head. 
Perforate the tympanic membrane on one side with a 
needle, and pass a bristle through the hole and down the 
Lustachian tube nto the mouth. 
d. Two rounded prominences at the sides of the roof of 
the mouth caused by the eyeballs. 
Press down one of the eyes with your finger, and note 
that rt can be made to project very considerably into the 
buccal cavity, 
2. On the Floor of the Mouth. 
a. The lower jaw, devoid of teeth, and forming a bony 
margin to the floor of the mouth: the rest of the floor 
is soft and fleshy, but is slightly stiffened by a car- 
tilaginous plate—the body of the hyoid. 
