26 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM 



In some cases the ninth vertebra has two demifacets on each 

 side; in these instances the tenth has a demifacet above and 

 none below. 



The tenth dorsal touches only one rib on a side, and has 

 a complete facet, mostly on the pedicle at its upper border. 

 The transverse process has a small facet. 



The eleventh dorsal has one complete facet on each side, 

 but none on the transverse process. 



The twelfth dorsal has a single facet on cadi side. It strongly 

 resembles a lumbar vertebra. 



The inferior articular surfaces turn out. The spinous pro- 

 cess is short and nearly horizontal. 



The transverse processes are short, and present neaT their 

 extremities the external, superior, and inferior tubercles, which 

 correspond respectively to the transverse, mammittary, and 

 accessory processes of the lumbar vertebrae. Rudiments of 

 these tubercles may be sometimes seen on the other dorsal 

 vertebrae. The row of costal facets forms the anterior border 

 of the intervertebral foramina. The ribs in moving intrude 

 somewhat upon the vessels and nerves in those foramina; 

 hence the "floating," most movable, ribs articulate with single 

 vertebrae. 



The Lumbar Vertebrae 



These are the largest of the movable vertebrae. They may 

 be distinguished by the absence of costal articular surfaces 

 and the absence of foramina through the transverse processes. 

 The body is reniform, broad transversely, deeper in front 

 than behind, and markedly constricted at the sides. The 

 pedicles are very thick, directed backward from the upper 

 part of the bodies. The lamince are short and thick, the superior 

 notches shallow. The spinous processes are horizontal, and 

 broad and thickened at their extremities. The spinal foramen 

 is triangular, larger than in the dorsal region, but smaller 

 than that in the cervical. 



The transverse processes are slender and project directly 

 out; they are in front of the articular processes, and are con- 

 sidered to be homologous with the ribs. Their extremities 

 lie in series with the external tubercles of the lower dorsal 

 transverse processes. The accessory process (anapophysis) 

 lies behind each lumbar transverse process at its base, and 



