IT.] THE SPINAL SKELETON. 29 



one of the other cervicals, when compared with a dorsal 

 vertebra, presents the following characters : 



The centrum is smaller, wider in proportion to its depth, 

 somewhat concave from side to side on its upper surface, and 

 from before backwards on its under surface. 



The neural canal and neural arch are wider, and the neural 

 spine much smaller and shorter (except in the case of the 

 seventh cervical vertebra), and often bifid, so that there are 

 two irregular processes projecting side by side. 



There is no long transverse process, but a short one juts 

 out from between the zygapophyses (therefore in the situation 

 of the transverse process of a dorsal vertebra), and another 

 projects from the body at the root of the pedicle, just at the 

 place where the capitular articular surface of a dorsal vertebra 

 is placed, and so may be called the capitular process. These 

 two short processes are connected towards their ends by a 

 bridge of bone which extends backwards and somewhat down- 

 wards from the capitular process to the posterior process. 



A space is thus enclosed on each side by the pedicle, the 

 two processes and the bridge, and it is on this account that 

 the cervical vertebrae are sometimes said to have perforated 

 transverse processes. 



As these processes are superimposed like the vertebrae that 

 support them, these successive, small, bony rings form a sort 

 of bony canal running upwards on each side of the neck-part 

 of the backbone, and this canal serves to protect the vertebral 

 artery which traverses it. The free end of each transverse 

 process divides into two blunt prominences called " tubercles." 



FIG. 41. THE Axis VERTEBRA. 



r, centrum ; s, neural spine ; d, tubercular process ; /, capitular process ; a, an- 

 terior articular surface for atlas ; z, postzygapophysis ; o, odontoid process ; 

 hy t median vertical ridge beneath centrum. 



10. The second cervical vertebra is peculiar, differs from 

 every other joint of the backbone, and has a special name, 

 the AXIS. 



