VEETEBEAL COLUMN. 291 



articular surface for the head of the rib. At 

 the posterior end are a similar pair of facets 

 for the riba of tlie succeeding vertebra. 



ii. The neural arch is notched, both in front and 



behind, for the passage of the spinal nerves, 

 iii. The transverse processes are 'short, stout, and 



horizontal, and bear on their under surfaces 



the articular facets for the tubercles of the 



ribs, 

 iv. The neural spine is long and slender, and 



slopes obliquely backwards. 

 V. The zyg'apophyses. The pre-zygapophyses face 



upwards and outwards, the post-zygapophyses 



downwards and inwards. 



b. The posterior three or four thoracic vertebrae. 



i. The centra are larger than in the anterior 

 thoracic vertebrte : the facet for the head of 

 each rib is confined to the anterior end of the 

 centrum, the posterior end having no articular 

 surface. 



ii. The neural spines are lower than in the anterior 

 vertebra, but longer from before backwards. 



iii. The transverse processes are placed further 

 back, and have no articular facets -for the 

 ribs. 



iv. Metapophyses appear in the ninth thoracic 

 vertebra, and increase considerably in size in 

 the succeeding ones. They are usually con- 

 fluent with the pre-zygapophyses in all except 

 the ninth thoracic vertebrae. 



4. The lumbar vertebrae. 



These are usually seven in. number: the most 

 anterior one may, however, bear ribs, in which case 

 it is reckoned as a thirteenth thoracic vertebra, and 

 the lumbar vertebrfe are then reduced to six. 



u2 



