THE LIPS, CHEEKS, AND VESTIBULE. 



1539 



Fat is found irregularly disposed among the muscles of the cheeks in varying 

 quantity, but in the depression in front of the masseter and superficial to the buccinator 

 there is a distinct ball of fat enclosed by a capsule, which is the remnant of the so- 



FIG. 1293. 



Frontal sinus 



Sphenoidal sinus 

 phenoid 



Orifice of Eustachian 

 tube 



Orbicularis oris 



{Esophagus 



Trachea 



Sagittal section of head ol young adult, three-fourths natural size. 



called "button" of infancy, a collection which gives resistance to the cheek and pre- 

 vents it from being flattened by atmospheric pressure during nursing. The mucous 

 membrane is reflected from the cheeks onto the jaws, where it covers the gums. 

 This line of reflection at the middle of the lower jaw is 7 or 8 mm. from the alveolar 



