The Vertebral Column. 



119 



particular regions also present certain features in common, so that 

 it is possible to classify them into cervical, thoracic, lumbar, sacral, 

 and caudal groups. 



A typical vertebra — for the characters of which any one of the 



p^5Jl. 



Fig. 56, Representative vertebrae: A, atlas, anterior surface; B, epistro 

 pheus, lateral surface; C, fifth cervical vertebra, anterior surface; D, fourth 

 dorsal, lateral surface; E, F, second lumbar vertebra, anterior and lateral 

 surfaces . 



a.a., anterior arch of atlas; a. p., posterior arch of atlas ; a.v., vertebral arch; 

 c.v., vertebral b(^y; d., dens epistrophei; f.a.a., anterior articular facet of 

 epistropheus; f.a.s., superior articular pit of atlas; f.a.s.', superior articular, 

 facet of epistropheus; f.c.i., inferior costal demifacet for head of rib; f.c.s., 

 superior costal demifacet; f.c.t., costal facet of transverse process; f.d., fovea 

 dentis; f.i., intervertebral foramen; f. tr., foramen transversarium;f. v., foramen 

 vertebrale; 1., lamina of vertebral arch; m.I., lateral mass of atlas; p.a., 

 accessory process of lumbar vertebra; p.a.i., inferior articular process; p.a.s., 

 superior articular process; p.m., mamillary process; p.s., spinous process; 

 p.s.a.,^ anterior spinous process; p.t., transverse process; p.t., triangular 

 process; r., radix of vertebral arch; r.a., r.p., anterior and posterior radices of 

 transverse process of cervical vertebra; t.a., t.p., anterior and posterior 

 tubercles of atlas. 



thoracic or lumbar series may be taken (Fig. 56, D-F) — consists of a 

 basal portion, the vertebral body (corpus vertebrae), and of a 

 dorsal, vertebral arch (arcus vertebrae). The two portions 



