THE SPINE. 137 



compared with the size of the head, that portion of the face 

 which is below them is very small, and has little depth. 



The upper maxillary hones have no sinuses in them ; and their 

 orbitar plates are not much elevated above the cavities for con- 

 taining the posterior teeth ; in consequence, the depth of the 

 face is very small, and its whole aspect is affected. 



The nose of the foetus differs greatly from that of the adult 

 in respect to its sinuses ; for not only are the maxillary cavities 

 wanting, but those of the frontal and sphenoidal bones also. 



The lower jaw is formed in two pieces, which unite at the 

 middle ; and hence the term syrr^jhysis is used in describing 

 the chin. The bone is not only less broad in proportion than 

 that of the adult, but the angles are more obtuse, and the pro- 

 cesses which arise from them are more sloping. 



The head of the foetus is much larger in proportion to the 

 body than that of the adult. 



Of the Trunk. 

 The Trunk consists of the Spine, Thorax, and Pelvis. 



The t Spine. 



The spine is the long pile of bones extending from the 

 condyles of the occiput to the end of the os coccygis. It some- 

 what resembles two unequal pyramids joined in a common base. 

 It is not, however, straight; for its upper part being drawn 

 backwards by strong muscles, it gradually advances forwards 

 to support the oesophagus, vessels of the head, &c. Then 

 it turns backwards, to make room for the heart and lungs. 

 It is next bent forwards to support the viscera of the abdomen. 

 It afterwards turns backwards for the enlargement of the pelvis. 

 And, lastly, It is reflected forwards, for sustaining the lowest 

 great intestines. 



The spine is commonly divided into true and false vertebrce ; 

 the former constituting the long upper pyramid, which has its 

 base below ; while the false vertebrae make the shorter lower 

 pyramid, whose base is above. 

 12* 



