VERTEBEAL COLUMN 63 



it had been abandoned as the name of the atlas. . The common German 

 and French terms are mere translations of the phrase, the second 

 cervical vertebra. 



Ossification of the Axis. In addition to the five principal centres 

 of ossification common to all vertebra?, the axis has four more, repre- 

 senting those of the body of the atlas which coalesces with it. These 

 additional centres are one at the tip and one in each side of the 

 odontoid process, and one in the caudal epiphyseal plate, usually 



FIG. 37. 



Spine. 



Lamina 



Caudal Articular Surface. 

 Pedicle. 



Foramen for Vertebral Artery. 

 Transverse Process. 



Body. 

 THE AXIS, POSTERIOR OR CAUDAL ASPECT. 



coalesced with the cephalic epiphyseal plate of the true body of the 

 axis. Smaller ossifications are said to appear late on the edge of the 

 spinous process and on the tip of the transverse process. 



The First Cervical Vertebra, or the Atlas, differs from all the rest 

 by its large, wing-like, transverse processes and by the absence of a 

 spinous process, but especially by the rudimentary condition of the 

 body ; the true body has been joined to the second vertebra to form 

 its odontoid process. 



What in other vertebra? is the body is here merely a bony bar 

 uniting the lateral masses on the ventral side (Fig. 38). This bar is 

 about twice as wide as it is long ; the ventral surface is convex and 

 the dorsal surface is concave. The cephalic margin is straight; the 

 caudal margin is emarginate, but presents at the middle a small 

 tubercle, which gives attachment to the longus colli muscle. 



The neural arch (Fig. 39) has a greater cephalo-caudal diameter 

 than the ventral arch. It is not so high as the neural arch of the 

 second vertebra. It is extremely thin and regularly convex from 

 side to side, there being no real division into pedicles and laminae. 





