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 , f 

 and caudal groups. 



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



PH& 



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

 pheus, lateral surface; C fifth cervicaLvertebra, 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 body; 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 

 vertebrate; 1., lamina of vertebral arch; m.l„ lateral mass of atlas; p. a., 

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

 superior articular process; p.ni, ., mamillary process;' p.s., spinous proTP?s; 

 p.s.a., anterior spinous pnfTSss; 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 



