THE SKELETON. 



67 



rior articular processes of the vertebra next in front, forming 

 a joint, and the two processes are united by ligaments. Sim- 



FIG. 18. 



FIG. 19. 



FIG. 18. A thoracic vertebra seen from behind, i.e., the end turned from the head. 



FIG. 19. Two thoracic vertebrae viewed from the left side, and in their natural 

 relative positions. C, the body ; A, neural area ; Fv, the neural ring ; Ps, spinous 

 process; Pas, anterior articular process; Pai, posterior articular process; Pt, 

 transverse process ; Ft, facet for articulation with the tubercle of a rib ; Fes, Fci, 

 articular surfaces on the centrum for articulation with a rib. 



ilarly its posterior articular processes form joints (Fig. 19) 

 with the anterior articular processes of the vertebra next be- 

 hind. 



The remaining processes are the transverse, Pt, which 

 run outwards and a little dorsally. Each of these has a 

 smooth articular surface, Ft, near its outer end. 



On the " body " are seen two articular surfaces on each 

 side : one, Fes, at its anterior, the other, Fci, at its posterior 

 end, and both close to the attachment of the neural arch. 

 Each of these surfaces forms with corresponding areas on 

 the vertebrae in front and behind a pit into which the end 

 of a rib fits and the rib attached in this way to the anterior 

 part of the " body " is also fitted on, a little way from its 

 dorsal end, to the articular surface at the end of the transverse 

 process. 



The Segments of the Axial Skeleton. If a thoracic verte- 

 bra, say the first (Fig. 20), be detached with the pair of ribs, 

 Cv 9 belonging to it and the bit of the sternum, S, to which 

 these ribs are fixed ventrally, we would find a bony parti- 

 tion formed by the body of the vertebra, lying between 



