94 



OSTEOLOGY. 



be recognised. These are the first, tenth, eleventh. 



FIG. 110. FIRST, NINTH, TENTH, ELEVENTH, AND TWELFTH 

 THORACIC VERTEBRA FROM THE LEFT SIDE. 



1. Inferior articular process, with 



laterally turned facet. 



2. Single facet for head of Xllth rib ; 



no facet on transverse process. 



3. Single facet for head of Xlth rib ; 



no facet on transverse process. 



4. Single facet for head of Xth rib. 



5. Occasional facet for head of Xth 



rib. 



6. Facet for head of IXth rib. 



7. Facet for head of Ilnd rib. 



8. Single facet for head of 1st rib. 



and twelfth, and sometimes 

 the ninth. 



The first thoracic ver- 

 tebra resembles the seventh 

 cervical in the shape of its 

 body, and the length and 

 direction of its spine. There 

 is a circular facet on either 

 side of the body for the head 

 of the first rib, and one facet 

 on each side at the inferior 

 border of its body, to com- 

 plete the socket for the head 

 of the second rib. Its trans- 

 verse processes are long, and 

 the superior intervertebral 

 notch is better marked than 

 in other members of the 

 thoracic series. The superior 

 articular surfaces are directed 

 backwards and upwards, not 

 laterally as in the lower 

 members of the series. 



The ninth thoracic 

 vertebra occasionally has 

 only the upper pair of facets 

 on its body ; at other times it 

 conforms to the usual type. 



The tenth thoracic ver- 

 tebra may have only one 

 complete costal facet on each 

 side for the tenth rib, though 

 sometimes the articular socket 

 may be completed by the 

 ninth thoracic vertebra. The 

 facet on the transverse pro- 

 cess is generally small, and 

 sometimes absent. 



The eleventh thoracic 

 vertebra has a complete 

 circular facet on the lateral 

 side of each root of the 

 vertebral arch for articula- 

 tion with the eleventh rib. 

 Its transverse processes are 



9. Facet on transverse process for short and stunted, and have 

 tuberosity of 1st rib. no facets 



10. Facet on transverse process for mi ,i.u +1,^ 



tuberosity of IXth rib. Lne twelfth thOraClC 



11. Facet on transverse process for Vertebra has a single facet 



tuberosity of xth rib, in this on eac h roo fc o f the vertebral 

 marked" "^ wel1 aroh for the twelfth rib. Its 



S. Superior^ Tubercles fMamillary. transverse prOCCSSeS, short 



I. Inferior 

 E. Lateral 



(corre- 

 sponding 

 to 



_J Accessory. 

 | Transverse 



and stunted, have no facets, 



of lumbar anc ^ are ^ r ken up into 

 smaller tubercles, called the 

 lateral, superior, and inferior tubercles. These are homologous with the trans- 

 verse, mamillary, and accessory processes of the lumbar vertebrae. Indica- 

 tions of these processes may also be met with in the tenth and eleventh 

 thoracic vertebrae. The twelfth thoracic vertebra may usually be distinguished 



