Chap. IV.] 



THE SKELETON. 



39 



Coronoid process. 



The inferior maxillary, or lower jaw, is the largest and 



strongest bone of the face, and serves for 



the reception of the lower teeth. At birth, 



it consists of two lateral halves, which 



join and form one bone during the first or 



second year. The lower jaw undergoes 



several changes in shape during life, owing 



mainly to the hrst 



and second denti- 

 tion, to the loss of 



teeth in the aged, 



and the subsequent 



absorption of that 



part of the bone 



which contained 



them. It articulates, by its condyles, with the sockets in the 



temporal bones. 



The hyoid, os hyoides, or tongue bone, is an isolated, U-shaped 

 bone lying in front of the throat, just above 

 "Adam's apple"; it supports the tongue, and 

 gives attachment to some of its numerous 

 muscles. 



The spine or vertebral column is formed of a 

 series of bones called vertebrse. The vertebrae 



are thirty-three in number, and according to the position 



they occupy are named : — 



Cervical 7 



Dorsal 12 



Lumbar 5 



Sacral 5 



Coccygeal 4 



33 



Fig. 39.— Hyoid 

 Bone. 



The vertebrre in the upper three portions of the spine are 

 separate throughout the whole of life ; but those found in 

 the sacral and coccygeal regions are, in the adult, firmly 

 united, so as to form two bones, five entering into the upper 

 bone, or sacrum, and four into the terminal bone of the spine, 

 or coccyx. 



Each vertebra consists of two essential parts, an anterior 



