THE SPINE. 87 



number is the same in all the mammalia, with a few ex- 

 ceptions. A cervical vertebra is distinguished by the 

 foramen in its transverse process, the large size of the 

 spinal foramen, the nearly horizontal position of the 

 articular surfaces, and the bifid spinous process. The 

 body is small, concave above, with a rather prominent 

 rim, and is convex below. The transverse processes 

 present two projections, the anterior and posterior 

 tubercles. The laminae are narrow, long, and thin, 

 and slightly overlap. The first, second, and seventh 

 cervical are peculiar. The first cervical, or atlas, articu- 

 lates above with the skull. It has neither body nor 



Tubereff 



^_ ^_^ *- far 



Tro*l.r '"' ~ *"" 



Spt'x. 



FIG. 36. THE ATLAS. 



spinous process, and consists of two arches anterior 

 and posterior and two lateral masses. The anterior 

 arch about one-sixth of the bone presents anteriorly 

 a tubercle, posteriorly a slightly concave articular facet, 

 for articulation with the odontoid process of the axis. 

 The anterior arch is convex from side to side anteriorly; 

 posteriorly, it is concave. The posterior arch forms 

 nearly one-half of the circumference of the bone; it 

 terminates posteriorly in a rudimentary spinous process, 

 or tubercle, for the attachment of muscles. On the 

 upper surface of the posterior arch, just behind the 

 articular surface for the condyles of the occipital bone, 



