VERTEBRAL COLUMN 



127 



Fro. 86. 



FIG. 87. 



A CERVICAL VERTEBRA. 

 UPPER VIEW. 



1, centrum : 2, lamina ; 3, pedi- 

 cle ; 4, spinous process ; 5, trans- 

 verse and costal processes; 6, 

 foramen for the vertebral artery ; 

 7, superior articular process; 8, 

 inferior articular process; 9, 

 elevated lateral border of the 

 centrum. 



THE AXIS. SIDE VIEW. 



1, centrum ; 2, odontoid 

 process; 3, articular facet; 

 4, arch; 5, spinous process; 

 6, transverse process, with 

 the vertebral foramen ; 7, 8, 

 superior and inferior artic- 

 ular processes. 



process. The costal element is much reduced, however, and sometimes 

 absent ; on the other hand, it may be enlarged to such an extent as 

 to constitute a cervical rib, a condition not yet reported as occurring 



in the cat. The laminae are 



the largest of any of the cer- 

 vical series, and the spinous 



process is the longest (hence 



this vertebra has been called 



the vertebra prominens) ; its 



tip, however, is not normally 



bifid. 



The Third, Fourth, and 



Fifth Cervical Vertebrae are 



very much alike, and are to 



be distinguished by their relative size, the third 



being the smallest and the fifth the largest. 

 The Axis (Fig. 87) presents all the features possessed by the axis 

 of the cat, but the cephalo-caudal diameters of all the parts are much 

 diminished. 



The body is quadrate, and its odontoid process is long and stout. 

 The pedicles are short and narrow ; the transverse processes are 

 small and simple and pierced by large arterial canals. The cephalic 

 articular processes are circular and flat or slightly saddle-shaped ; 

 their surfaces face toward the skull and laterally. The caudal artic- 

 ular processes resemble the processes of 

 the other cervical vertebrae ; their surfaces 

 face toward the sacrum and ventrally. The 

 laminae are longer than the laminae of the 

 other vertebrae ; the spinous process is 

 short and bifid. The neural canal is 

 almost round. 



The Atlas (Fie-. 88) as compared with * anterior arch ; 2 > a '-"iar facet for 



the odontoid process; 3, posterior arch; 



the atlas of the cat is merely a ring of bone. 4> groove for the vertebral arter y; 5 > 



/ transverse process; 6, vertebral foramen ; 



The Ventral bar (anterior arch) is ', superior articular process; . tubercle 



for the transverse ligament. 



slightly wider than the dorsal bar (pos- 

 terior arch), which bears a trace of the spinous process. The trans- 

 verse processes, instead of being large and wing-like, are small 

 masses, whereof the bases are pierced completely by the arterial canals. 



FlG - 



THE ATLAS. UPPER VIEW. 



