CEEVICAIi VEETEBE^ 269 



transverse processes, through which the vertebral 

 arteries run. 



a. The first, or atlas vertebra, differs very markedly 

 from all the others : its more important characters- 

 are as follows. 



i. The neural canal is very large, and is divided into 

 two parts by a transverse ligament, which is 

 usually preserved in the dried skeleton : of 

 these, the upper and larger is the true neural 

 canal, giving passage to the spinal cord ; while 

 the lower and smaller one lodges the odontoid 

 process of the second vertebra. 



ii. The centrum is probably represented by the 

 odontoid process, which has become detached 

 from the atlas, and fused with the centrum 

 of the second vertebra. The mid-ventral 

 portion of the atlas is very narrow, and is 

 produced backwards into a short process. 



iii. The neural spine is a very insignificant ridge, 

 most prominent in front. 



iv. The transverse processes are broad horizontal 

 lameUse, perforated at their bases by longi- 

 tudinal vertebrarterial canals. In front of 

 each transverse process the canal is continued 

 upwards as a groove to a foramen in the 

 neural arch, through which the vertebral 



Fig. 57.— LepuB cunicnlus. Selected vertebrae, (a. m. m.) 

 I. First cervical vertebra, or atlas, from the dorsal surface. 

 II. Second cervical vertebra, or axis, from the right side. III. Fifth 

 cervical vertebra ; anterior surface. IV. Fourth thoracic vertebra, 

 from the right side. V. Fourth thoracic vertebra, and fourth pair 

 of ribs ; anterior surface. VI. Second lumbar vertebra, from the 

 right side. VII. Second lumbar vertebra ; anterior surface. 



AP, anapophysis. AZ, anterior or pre-zygapophysis. C, centrum. 

 CB, epiphysis of centrum. CK, cervical rib. PH, facet for oapitulum or 

 head of the fourth rib. FH', facet for oapitulum of the fifth rib. PO, facet 

 for odontoid process. PT, facet for tubercle of fourth rib. HP, hypapophysis. 

 MP, metapophysis. US, neural spine, or spinous process. OP, odontoid 

 process. PZ, post-zygapophysis. BC, oapitulum or head of rib. EP, pro- 

 cess of rib for attachment of ligaments. RS, sternal portion of rib. RT, 

 tubercle of rib. EV, vertebral portion of rib. S, sternum. TP, transverse 

 process. VA, vertebrarterial canal. 



