LUMBAR VERTEBRAE. 123 



the next vertebra, than in any other part of the dorsal region. The transverse 

 processes are very short, tubercular at their extremities, and have no articular 

 facets for the tubercles of the ribs. The spinous process is short, nearly hori- 

 zontal in direction, and presents a slight tendency to bifurcation at its extremity. 

 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 outwards, like those of the lumbar vertebrae ; by the general form of 

 the body, laminae, and spinous process, approaching to that of the lumbar 

 vertebrae ; and by the transverse processes being shorter, and the tubercles at 

 their extremities more marked. 



CHARACTERS OF THE LUMBAR VERTEBRA. 



The Lumbar Vertebras (Fig. 74) are the largest segments of the vertebral 

 column. The body is large, broader from side to side than from before back- 

 wards, about equal in depth in front and behind, flattened or slightly concave 

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



Fig. 74. A Lumbar Vertebra. 

 Super. Artec* Proe. 



sides, presenting prominent margins, which afford a broad basis for the support 

 of the superincumbent weight. The pedicles are very strong, directed back- 

 wards from the upper part of the bodies ; consequently the inferior inter verte- 

 bral notches are of large size. The laminae are short, but broad and strong ; 

 and the foramen triangular, larger than in the dorsal, smaller than in the cer- 

 vical region. The superior articular processes are concave, and look almost 

 directly inwards ; the inferior, convex, look outwards and a little forwards ; the 

 former are separated by a much wider interval than the latter, embracing the 

 lower articulating processes of the vertebra above. The transverse processes 

 are long, slender, directed transversely outwards in the upper three lumbar 

 vertebrae, slanting a little upwards in the lower two. By some anatomists they 

 are considered homologous with the ribs. Of the two tubercles noticed in con- 

 nection with the transverse processes in the dorsal region, the superior ones 

 become connected in this region with the back part of the superior articular 

 processes. Although in man they are comparatively small, in some animals 

 they attain considerable size, and serve to lock the vertebrae more closely to- 

 gether. The spinous processes are thick and broad, somewhat quadri-lateral, 

 horizontal in direction, thicker below than above, and terminating by a rough 

 uneven border. 



The Fifth Lumbar vertebra is characterized by having the body much thicker 

 in front than behind, which accords with the prominence of the sacro-vertebral 

 articulation, by the smaller size of its spinous process, by the wide interval 

 between the inferior articulating processes, and by the greater size and thick- 

 ness of its transverse processes. 



