LUMBAR VERTEBRA. 



151 



tht- purpose of more closely connecting the segments of this portion of the spine 

 or for muscular and ligamentous attachment. (See below, ttcclfth dorsal vertebra.) 



The peculiar dorsal vertebrae are the first, ninth, tenth, eleventh, and twelfth 

 (Fig. 114). 



The First Dorsal Vertebra presents, on each side of the body, a single entire 

 articular facet for the head of the first rib and a half facet for the upper half of 

 the second. The upper surface of the body is like that of a cervical vertebra, 

 being broad transversely, concave, and lipped on each side. The articular sur- 

 fa<'cs are oblique, and the spinous process thick, long, and almost horizontal. 



The Ninth Dorsal has no demi-facet beloAv. In some subjects, however, the 

 ninth has two demi-facets on each side, then the tenth has a demi-facet at the upper 

 part : none below. 



The Tenth Dorsal has (except in the cases just mentioned) an entire articular 

 facet on each side above, which is partly placed on the outer surface of the pedicle. 

 It has no demi-facet below. 



In the Eleventh Dorsal the body approaches in its form and size to the lumbar. 

 The articular facets for the heads of the ribs, one on each side, are of large size, 

 and placed chiefly on the pedicles, which are thicker and stronger in this and the 

 next vertebra than in any other part of the dorsal region. The spinous process is 

 short, nearly horizontal in direction, and presents a slight tendency to bifurcation 

 at its extremity. The transverse processes are very short, tubercular at their 

 extremities, and have no articular facets for the tubercles of the ribs. 



The Twelfth Dorsal has the same general characters as the eleventh, but may 

 be distinguished from it by the inferior articular processes being convex and 

 turned outward, like those of the lumbar vertebrae ; by the general form of the 

 bn'ly. laminae, and spinous process, approaching to that of the lumbar vertebrae; 

 and by the transverse processes being shorter, and marked by three elevations, the 

 superior, inferior, and external tubercles, which correspond to the mammillary, 

 accessory, and transverse processes of the lumbar vertebrae. Traces of similar 

 elevations are usually to be found upon the other dorsal vertebrae (vide ut supra). 



Characters of the Lumbar Vertebrae. 



The Lumbar Vertebrae (Fig. 115) are the largest segments of the vertebral 

 column, and can at once be distinguished bv the absence of the foramen in the 



Superior articular pruce*$ 



FIG. 115. Lumbar vertebra. 



transverse process, the characteristic point of the cervical vertebrae, and by the 

 absence of any articulating facet on the side of the body, the distinguishing mark 

 of the dorsal vertebrae. 



The body is large, and has a greater diameter from side to side than from before 

 backward, slightly thicker in front than behind, flattened or slightly concave above 

 and below, concave behind, and deeply constricted in front and at the sides, 



