268 



Anatomy of Skeleton 



new-born skull. We have therefore to deal with an excessive growth in length in the 

 front part of the skull during the change to the adult type, as well as with a vertical 

 increase, both affecting the anterior portion of the skull ; the former is mainly due to 

 cranial growth in front and the latter mainly to facial increase, but the face increases 

 in depth also with the added cranial length. When the facial growth occurs without 

 the proportionate cranial growth the adult skull presents the appearance of prognathism 

 that characterises the heads of the lower races. 



The characters of the face in the new-born skull depend almost entirely on the 

 immature condition of the maxillae and mandible. Each maxilla (Fig. 212) is flattened 

 vertically, owing on the one hand to the almost .complete absence of the alveolar pro- 

 cess and on the other to the small size of the antrum, which only occupies the inner 

 part of the bone to a small extent, leaving the remainder more or less flat. Whatever 

 prominence there may be in the maxilla is due to the tooth germs embedded in the 



pffal) 

 FIG. 213. Occipital, frontal, and temporal at birth. 



bone, but these are properly supra-alveolar, as can be seen by comparing the skull 

 with an adult one. 



The results of this shallowness of the maxillse can be well seen in the nasal fossae. 

 These are much broader compared with their height than in the adult, and the 

 various bones that make their walls are correspondingly modified : thus the palate 

 has a short but broad vertical plate, the internal pterygoid plate is similarly 

 modified, and the vomer shows a decreased vertical height while its breadth is pro- 

 portionately greater, and thus it forms a gutter that holds the septal cartilage in 

 it. On the other hand, the ethmoid and lachrymals lie above the level of the 

 maxillary body and are not affected by its subsequent growth, so they present at 

 birth no essential differences, save in size, from the adult conditions. The malar, 

 owing to the want of development of the alveolar region, overhangs the opening of 

 the mouth on each side and may be felt easily through the mucous membrane. 

 Another result of the alveolar deficiency is seen in the hard palate : it is much less 

 curved than in the adult in fact it is nearly flat, for in the full-grown bone the 

 concavity is largely due to the presence of the alveolar eminences.* The posterior 



* In old toothless jaws with loss of alveolar processes there is a return to the flattened palate. 



