LUMBAK VEETEBE^E. 



95 



from the eleventh by the arrangement of its inferior articular processes, which 

 resemble those of the lumbar series in being turned laterally ; but the eleventh 

 occasionally displays the same arrangement, in which case it is not always easy 

 to distinguish between them. 



Mamillary process 



Vertebrae Lumbales. 



The lumbar vertebrae, five in number, are the largest of the movable vertebrae. 

 They have no costal articular facets, nor are their transverse processes pierced by 

 a foramen. In this way they can be readily distinguished from the members of 

 the cervical and thoracic 

 series. Spinous process 



The body is kidney- 

 shaped in outline, and 

 of large size, exhibiting a 



gradual transition from BLli Inferior articular process 



the thoracic form in the 

 higher segments. The 

 transverse diameter is 

 usually about a half 

 greater than the antero- 

 posterior. The anterior 

 vertical thickness is 

 slightly greater than the 

 posterior, being thus 

 adapted to the anterior 

 convex curve of the 

 column in this region. 



The roots of vertebral 

 arches (O.T. pedicles), 

 directed horizontally back- 

 wards, are short and stout ; 

 the superior notches are 

 shallow, but deeper than 

 in the thoracic region ; the 

 inferior grooves are deep. 

 The laminae are broad and 

 nearly vertical, sloping but 

 little. They support on 

 their inferior margins the 

 inferior articular processes. 

 The vertebral foramen is 

 large and triangular. 



The spinous processes, 

 spatula shaped, with a 

 thickened posterior mar- 

 gin, project backwards and 

 slightly downwards. The 

 transverse processes, more 

 slender than in the thor- 

 acic region, pass horizon- 

 tally laterally, with a 

 slight backward inclination and usually with an upward tilt. Arising from the 

 junction of the roots of the vertebral arches with the laminae in the higher 

 members of the series, they tend to advance so as to become fused with the lateral 

 side of the root and posterior aspect of the body in the lower two lumbar vertebrae. 

 In these latter vertebras the superior intervertebral grooves are carried obliquely 

 across the superior surfaces of the bases of the transverse processes. The transverse 

 processes lie in line with the lateral tubercles of the lower thoracic vertebrae, with 



Body 

 Superior articular process 



I 



Mamillary process 



Transverse process 



Body 



Spinous process 



Inferior articular process 



FIG. 111. THIRD LUMBAR VERTEBRA, (A) from above, 

 and (B) from the left side. 



