300 



THE RABBIT 



narrow owing to the absence of a distinct centrum. The neural canal is large ; 

 and it is divided by a ligament into an upper part through which the spinal cord 

 passes, and a lower part into which fits the odontoid process of the axis. The 

 transverse processes are very broad. Anteriorly there are two large concavities, 

 the articular surfaces for the occipital condyles of the skuU. 



Draw the atlas vertebra from above and from in front. {See Fig. 98, page 298. ) 



{b) The Axis. 



This is the second cervical vertebra. It has a large crest-Uke neural spine ; 

 and its centrum bears the odontoid process, which represents a fusion of the 

 centra of the atlas and the axis. The transverse processes are small, and each 

 is perforated by the vertebra-arterial foramen. The zygapophyses occur only on 

 the posterior surface of the arch. 



Draw the axis vertebra as viewed from the left side and from in front. 



-Neural spine 



Transverse process 

 i--Po8terior 

 zygapophysis 



Qervical rib 



Vertebral foramen 

 Facet for articulation 

 with Atlas' 



Odontoid' process 



Fig. 99. — A. Left-side view ; 



and B. Anterior view of the Axis Vertebra 

 of the Rabbit. 



(c) The Sixth Cervical Vertebra. 



This [vertebra has a centrum bearing a cervical rib fused with the trans- 

 verse process on each side. The transverse processes are perforated by the 

 vertebra-arterial foramina. The neural spine is short. Both anterior and 

 posterior zygapophyses occur on the neural arch. 



Draw this vertebra from the left side and from in front. 



Anterior 

 zygapophysis 



'-4'osterior 

 zygapophysis 



Neural spijie 

 Anterior 

 zygapophysis 



Vertebrarterial 

 canal- 

 Cervical rib--- 



Fio. 100.- — A. Left-side view ; and B. Anterior view of the Sixth Cervical Vertebra 



of the Rabbit. 



2. The Thoracic Region. 



This region consists of twelve or thirteen vertebrae which bear movably 

 articulated ribs. The neural spines are long. The transverse processes are 

 short and stout ; and each, in the first nine vertebras, is provided on the under- 

 side with a facet for the articulation with the tuberculum of the rib. The short 

 and thick centrum bears on each side a facet for the head (capitulum) of the rib. 



