THE SKELETON 11 



The vertebral column may be divided into 

 cervical, thoracic, lumbar, sacral, and coccygeal 

 regions ; but the limits of these are not as well 

 defined as in mammals. 



The cervical vertebrae (Fig. 1), forming the 

 skeleton of the neck, are thirteen in number. 

 They have long bodies, and, except towards 

 the end of the series, poorly developed spinous 

 processes. The ventral process is of consider- 

 able size in the last four or five bones, and an 

 examination of the vertebrae in series will show 

 that the process is produced by the union of pro- 

 jections separated off from the two transverse 

 processes. The transverse processes are con- 

 nected with the cranial articular processes, 

 and are prolonged by thin, spicular projections 

 (cervical ribs) pointing in a caudal direction. 

 A transverse foramen pierces the root of each 

 transverse process, this forming an outstand- 

 ing characteristic of the cervical vertebrae. 



The first cervical vertebra, or atlas, differs 

 from all the rest in its small size and its narrow 

 ring-like form. It possesses a deep concavity 

 for articulation with the single occipital condyle 

 of the skull ; and articulates with the second 

 vertebra by three points — a single, convex, 

 ventral surface, and two small lateral areas 



