222 ACTIVE ORGANS OP THE HEAD. 



infant lias the rami of the lower jaw very oblique instead 

 of vertical, as in the adult. The posterior nares and the 

 pterygoid processes look also obliquely forward and down- 

 ward, while in the adult they become vertical by the de- 

 velopment of the maxillary sinuses, carrying them back- 

 wards. The palatine region, from the same want of de- 

 velopment in the maxillary sinus and forward obliquity of 

 the pterygoid processes, is much shorter from before back- 

 wards, than in the adult. 



It is thus seen how much the configuration of the face 

 depends on the presence, absence, or partial development 

 of these sinuses. 



The cranium is remarkable for its early ossification, which 

 commences first in the vault, though at birth it is found 

 more advanced in the base. Indeed, at this period, the 

 base is firm and immovable, while the vault has its bones 

 separated by intervening membranes, which allow of con- 

 siderable movement, so much so that during labor there is 

 always more or less overlapping of the bones. It is at this 

 period the anterior and posterior openings in the cranium, 

 called fontanelles, are seen. 



CHAPTEK II. 



ACTIVE ORGANS OF THE HEAD. 



THESE organs include 



1. Organs of Digestion. 



2. Organs of Expression and Speech. 



3. Organs of Sense, including the Nerves. 



4. Organs of Circulation. 



5. The Fascia. 



The organs of digestion comprise those of 



1. Prehension, 3. Insalivation, 



2. Mastication, 4. Deglutition, 



